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Investment Securities - Amortized Cost and Estimated Fair Value of Debt Securities by Contractual Maturity (Detail) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Debt securities available for sale:
Due in one year or less	$ 5,023
Due after one year through five years	2,921
Due after five years through ten years	50
Total available for sale (amortized cost)	7,994
Mortgage-backed securities	2,697
Investment securities available for sale, amortized cost	10,691	$ 11,193
Debt securities held to maturity:
Due in one year or less	15
Due after one year through five years	1,179
Due after five years through ten years	1,351
Due after ten years	963
Total available for held to maturity (amortized cost)	3,508
Mortgage-backed securities	11,822
Amortized cost for held to maturity	15,330	13,530
Debt securities available for sale:
Due in one year or less	4,970
Due after one year through five years	2,856
Due after five years through ten years	44
Total available for sale (fair value)	7,870
Mortgage-backed securities	2,570
Total	10,440	10,749
Debt securities held to maturity:
Due in one year or less	14
Due after one year through five years	1,147
Due after five years through ten years	1,327
Due after ten years	922
Total available for held to maturity (fair value)	3,410
Mortgage-backed securities	10,898
Total	$ 14,308	$ 12,375

Capitalized Servicing Assets - Additional Information (Detail) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Jan. 31, 2019	Dec. 31, 2023	Dec. 31, 2022
Servicing Assets at Fair Value [Line Items]
Loans receivable		$ 134,936	$ 132,074
Purchase of residential mortgage loans		$ 350
Weighted average discount rates used to estimate fair value of capitalized mortgaged loan servicing assets		14.43%	18.00%
Residential Mortgage Loans [Member]
Servicing Assets at Fair Value [Line Items]
Total loans serviced for others		$ 155,342	$ 118,392
Fair value of residential loan servicing assets		$ 611	$ 336
Weighted average discount rates used to estimate fair value of capitalized mortgaged loan servicing assets		11.45%	12.29%
Residential Mortgage Loans [Member] \| LIBOR [Member]
Servicing Assets at Fair Value [Line Items]
Discounted rate represented weighted-average option-adjusted basis spread point percentage			8.81%
Residential Mortgage Loans [Member] \| SOFR [Member]
Servicing Assets at Fair Value [Line Items]
Discounted rate represented weighted-average option-adjusted basis spread point percentage		7.90%
Residential Real Estate [Member]
Servicing Assets at Fair Value [Line Items]
Loans receivable		$ 19,500
Fair value of residential loan servicing assets	$ 1,100
Purchase price of servicing rights	$ 12
Commercial Mortgage Loans [Member]
Servicing Assets at Fair Value [Line Items]
Total loans serviced for others		28,030	$ 26,007
Fair value of residential loan servicing assets		$ 193	$ 156
Weighted average discount rates used to estimate fair value of capitalized mortgaged loan servicing assets		14.43%

Regulatory Matters - Summary of Required Minimum and Well Capitalized Capital Ratios (Detail)	Dec. 31, 2023
M&T (Consolidated) [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
CET1 to RWA, Minimum	4.50%
Tier 1 capital to RWA, Minimum	0.060
Total capital to RWA, Minimum	0.080
Leverage - Tier 1 capital to average total assets, as defined	0.040
Tier 1 capital to RWA, Well capitalized	0.060
Total capital to RWA, Well capitalized	0.100
Bank Subsidiaries [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
CET1 to RWA, Minimum	4.50%
Tier 1 capital to RWA, Minimum	0.060
Total capital to RWA, Minimum	0.080
Leverage - Tier 1 capital to average total assets, as defined	0.040
CET1 to RWA, Well Capitalized	6.50%
Tier 1 capital to RWA, Well capitalized	0.080
Total capital to RWA, Well capitalized	0.100
Leverage - Tier 1 capital to average total assets, as defined	0.050

Earnings per common share (Tables)

12 Months Ended

Dec. 31, 2023

Earnings Per Share [Abstract]

Computations of Basic Earnings Per Common Share

The computations of basic earnings per common share follow:


	Year Ended December 31,
(Dollars in millions, except per share, shares in thousands)	2023			2022			2021
Income available to common shareholders:
Net income	$	2,741		$	1,992		$	1,859
Less: Preferred stock dividends		(100	)		(97	)		(73	)
Net income available to common equity		2,641			1,895			1,786
Less: Income attributable to unvested stock-based compensation awards		(5	)		(4	)		(9	)
Net income available to common shareholders	$	2,636		$	1,891		$	1,777
Weighted-average shares outstanding:
Common shares outstanding (including common stock issuable) and unvested stock-based compensation awards		166,662			163,489			129,539
Less: Unvested stock-based compensation awards		(301	)		(315	)		(890	)
Weighted-average shares outstanding		166,361			163,174			128,649

Basic earnings per common share	$	15.85		$	11.59		$	13.81

Computations of Diluted Earnings Per Common Share

The computations of diluted earnings per common share follow:


	Year Ended December 31,
(Dollars in millions, except per share, shares in thousands)	2023			2022			2021
Net income available to common equity	$	2,641		$	1,895		$	1,786
Less: Income attributable to unvested stock-based compensation awards		(5	)		(4	)		(9	)
Net income available to common shareholders	$	2,636		$	1,891		$	1,777
Adjusted weighted-average shares outstanding:
Common shares outstanding (including common stock issuable) and unvested stock-based compensation awards		166,662			163,489			129,539
Less: Unvested stock-based compensation awards		(301	)		(315	)		(890	)
Plus: Incremental shares from assumed conversion of stock-based compensation awards and warrants to purchase common stock		641			856			163
Adjusted weighted-average shares outstanding		167,002			164,030			128,812

Diluted earnings per common share	$	15.79		$	11.53		$	13.80

Significant accounting policies

12 Months Ended

Dec. 31, 2023

Accounting Policies [Abstract]

Significant accounting policies

M&T BANK CORPORATION AND SUBSIDIARIES

Notes to Financial Statements

1. Significant accounting policies

M&T is a BHC headquartered in Buffalo, New York. Through subsidiaries, M&T provides individuals, corporations and other businesses, and institutions with commercial and retail banking services, including loans and deposits, mortgage banking, trust, asset management and other financial services. Banking activities are largely focused on consumers residing in New York State, Maryland, New Jersey, Pennsylvania, Delaware, Connecticut, Massachusetts, Maine, Vermont, New Hampshire, Virginia, West Virginia, and the District of Columbia and on small and medium-size businesses based in those areas. Certain subsidiaries also conduct activities in other areas.

The accounting and reporting policies of the Company are in accordance with GAAP and general practices within the banking industry. The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.

At December 31, 2023, the Company reclassified the substantial majority of its loans secured by commercial real estate that were considered owner-occupied to commercial and industrial loans to reflect the variation in the management and underlying risk profile of such loans as compared with investor-owned commercial real estate loans. Also in the fourth quarter of 2023, the Company began presenting "professional and other services" as an individual component of "other expense" while combining the presentation of "printing, postage and supplies" into "other costs of operations" within the Consolidated Statement of Income. Prior periods were reclassified to conform to the current presentation. As further described in note 23, in the fourth quarter of 2023 the Company completed modifications to its management reporting system to conform its internal profitability reporting with certain organizational changes that resulted in the realignment of its business operations into three reportable segments: Commercial Bank, Retail Bank and Institutional Services and Wealth Management. Prior period reportable segment results disclosed in note 23 have been presented in conformity with the new segment reporting structure.

The Company's significant accounting policies are as follows:

Consolidation

The consolidated financial statements include M&T and all of its subsidiaries. All significant intercompany accounts and transactions of consolidated subsidiaries have been eliminated in consolidation. The financial statements of M&T included in note 26 report investments in subsidiaries under the equity method. Information about some limited purpose entities that are affiliates of the Company but are not included in the consolidated financial statements appears in note 20.

Consolidated Statement of Cash Flows

For purposes of this statement, cash and due from banks and federal funds sold are considered cash and cash equivalents.

Securities purchased under agreements to resell and securities sold under agreements to repurchase

Securities purchased under agreements to resell and securities sold under agreements to repurchase are treated as collateralized financing transactions and are recorded at amounts equal to the cash or other consideration exchanged. It is generally the Company’s policy to take possession of collateral pledged to secure agreements to resell.

Trading account

Financial instruments used for trading purposes are stated at fair value. Realized gains and losses and unrealized changes in fair value of financial instruments utilized in trading activities are included in “trading account and other non-hedging derivative gains” in the Consolidated Statement of Income.

Investment securities

Investments in debt securities are classified as held to maturity and stated at amortized cost when management has the positive intent and ability to hold such securities to maturity. Investments in other debt securities are classified as available for sale and stated at estimated fair value with unrealized changes in fair value included in “accumulated other comprehensive income (loss), net.” Amortization of premiums and accretion of discounts for investment securities available for sale and held to maturity are included in interest income.

Investments in equity securities having readily determinable fair values are stated at fair value and unrealized changes in fair value are included in earnings. Investments in equity securities that do not have readily determinable fair values are stated at cost minus impairment, if any, plus or minus changes resulting from observable price changes in orderly transactions for the identical or a similar investment of the same issuer. Other equity securities include stock of the FRB of New York and the FHLB of New York.

GAAP requires an allowance for credit losses be deducted from the amortized cost basis of financial assets, including investment securities held to maturity, to present the net carrying value at the amount that is expected to be collected over the contractual term. In cases where fair value of an available-for-sale debt security is less than its amortized cost basis and the Company does not intend to sell the available-for-sale debt security and it is not more likely than not that the Company will be required to sell the security before recovery of the amortized cost basis, the difference between the fair value and the amortized cost basis is separated into (a) the amount representing the credit loss and (b) the amount related to all other factors. The amount related to the credit loss is recognized as an allowance for credit losses while the amount related to other factors is recognized in other comprehensive income, net of applicable income taxes. If the Company intends to sell the security or it is more likely than not to be required to sell the security before recovery of the amortized cost basis, the security is written down to fair value with the entire amount recognized in earnings. Subsequently, the Company accounts for the debt security as if the security had been purchased on the measurement date of the write down at an amortized cost basis equal to the previous amortized cost basis less the amount of the write down recognized in earnings. Realized gains and losses on the sales of investment securities are determined using the specific identification method.

Loans and leases

The Company’s accounting methods for loans depend on whether the loans were originated or acquired by the Company.

Originated loans and leases

Loan fees and certain direct loan origination costs are deferred and recognized as an interest yield adjustment over the life of the loan. Net deferred fees have been included in unearned discount as a reduction of loans outstanding. Interest income on loans is accrued on a level yield method. Loans are placed on nonaccrual status and previously accrued interest thereon is charged against income when it is probable that the Company will be unable to collect all amounts according to the contractual terms of the loan agreement or when principal or interest is delinquent 90 days. Certain loans greater than 90 days delinquent continue to accrue interest if they are well-secured and in the process of collection. Loans less than 90 days delinquent are deemed to have an insignificant delay in payment and generally continue to accrue interest. Interest received on loans placed on nonaccrual status is generally applied

to reduce the carrying value of the loan or, if principal is considered fully collectable, recognized as interest income. Nonaccrual commercial and industrial loans and commercial real estate loans are returned to accrual status when borrowers have demonstrated an ability to repay their loans and there are no delinquent principal and interest payments. Loans secured by residential real estate are returned to accrual status when they are deemed to have an insignificant delay in payments of 90 days or less. Consumer loans not secured by residential real estate are returned to accrual status when all past due principal and interest payments have been paid by the borrower. Loan balances are charged-off when it becomes evident that such balances are not fully collectable. For commercial and industrial loans and commercial real estate loans, charge-offs are recognized after an assessment by credit personnel of the capacity and willingness of the borrower to repay, the estimated value of any collateral, and any other potential sources of repayment. A charge-off is recognized when, after such assessment, it becomes evident that the loan balance is not fully collectable. For loans secured by residential real estate, the excess of the loan balances over the net realizable value of the property collateralizing the loan is charged-off when the loan becomes 150 days delinquent. Consumer loans are generally charged-off when the loans are 91 to 180 days past due, depending on whether the loan is collateralized and the status of repossession activities with respect to such collateral.

During the normal course of business, the Company modifies loans to maximize recovery efforts from borrowers experiencing financial difficulty. Such loan modifications typically include payment deferrals and interest rate reductions but may also include other modified terms. Those modified loans may be considered nonaccrual if the Company does not expect to collect the contractual cash flows owed under the loan agreement. On January 1, 2023, the Company adopted amended guidance that eliminated the accounting guidance for troubled debt restructurings while expanding disclosure requirements for certain loan refinancings and restructurings by creditors when a borrower is experiencing financial difficulty. The amended guidance also requires disclosure of current period gross charge-offs by year of origination. Prior to January 1, 2023, if the borrower was experiencing financial difficulty such that the Company did not expect to collect the contractual cash flows owed under the original loan agreement and a concession in loan terms was granted, the Company considered the loan modification as a troubled debt restructuring and such loans were classified as either nonaccrual or renegotiated loans.

Commitments to sell real estate loans are utilized by the Company to hedge the exposure to changes in fair value of real estate loans held for sale. The carrying value of hedged real estate loans held for sale recorded in the Consolidated Balance Sheet includes changes in estimated fair value during the hedge period, typically from the date of close through the sale date. Valuation adjustments made on these loans and commitments are included in “mortgage banking revenues” in the Consolidated Statement of Income.

Acquired loans and leases

Expected credit losses for PCD loans are initially recognized as an allowance for credit losses and are added to the purchase price to determine the amortized cost basis of the loans. Any non-credit discount or premium resulting from acquiring such loans is recognized as an adjustment to interest income over the remaining lives of the loans. Subsequent changes in the amount of expected credit losses on such loans are recognized in the allowance for credit losses in the same manner as originated loans. For all other acquired loans, the difference between the fair value and outstanding principal balance of the loans is recognized as an adjustment to interest income over the lives of those loans. Those loans are then accounted for in a manner that is similar to originated loans.

Allowance for credit losses

The allowance for credit losses is deducted from the amortized cost basis of financial assets to present the net carrying value at the amount that is expected to be collected over the contractual term of the asset considering relevant information about past events, current conditions, and reasonable and supportable forecasts that affect the collectability of the reported amount. In estimating expected losses in the loan and lease portfolio, borrower-specific financial data and macro-economic assumptions are utilized to project losses over a reasonable and supportable forecast period. Assumptions and judgment are applied to measure amounts and timing of expected future cash flows, collateral values and other factors used to determine the borrowers’ abilities to repay obligations. Subsequent to the forecast period, the Company utilizes longer-term historical loss experience to estimate losses over the remaining contractual life of the loans.

Assets taken in foreclosure of defaulted loans

Assets taken in foreclosure of defaulted loans are primarily comprised of commercial and residential real property and are included in “accrued interest and other assets” in the Consolidated Balance Sheet. An in-substance repossession or foreclosure occurs and a creditor is considered to have received physical possession of real estate property collateralizing a mortgage loan upon either (i) the creditor obtaining legal title to the real estate property upon completion of a foreclosure or (ii) the borrower conveying all interest in the real estate property to the creditor to satisfy that loan through completion of a deed in lieu of foreclosure or through a similar legal agreement. Upon acquisition of assets taken in satisfaction of a defaulted loan, the excess of the remaining loan balance over the asset’s estimated fair value less costs to sell is charged-off against the allowance for credit losses. Subsequent declines in value of the assets are recognized as “other costs of operations” in the Consolidated Statement of Income.

Premises and equipment

Premises and equipment are stated at cost less accumulated depreciation. Depreciation expense is computed principally using the straight-line method over the estimated useful lives of the assets.

Capitalized servicing rights

Capitalized servicing assets are included in “accrued interest and other assets” in the Consolidated Balance Sheet. Separately recognized servicing assets are initially measured at fair value. The Company uses the amortization method to subsequently measure servicing assets. Under that method, capitalized servicing assets are charged to expense in proportion to and over the period of estimated net servicing income.

To estimate the fair value of servicing rights, the Company considers market prices for similar assets and the present value of expected future cash flows associated with the servicing rights calculated using assumptions that market participants would use in estimating future servicing income and expense. Such assumptions include estimates of the cost of servicing loans, loan default rates, an appropriate discount rate, and prepayment speeds. For purposes of evaluating and measuring impairment of capitalized servicing rights, the Company stratifies such assets based on the predominant risk characteristics of the underlying financial instruments that are expected to have the most impact on projected prepayments, cost of servicing and other factors affecting future cash flows associated with the servicing rights. Such factors may include financial asset or loan type, note rate and term. The amount of impairment recognized is the amount by which the carrying value of the capitalized servicing rights for a stratum exceeds estimated fair value. Impairment is recognized through a valuation allowance.

Sales and securitizations of financial assets

Transfers of financial assets for which the Company has surrendered control of the financial assets are accounted for as sales. Interests in a sale of financial assets that continue to be held by the Company, including servicing rights, are initially measured at fair value. The fair values of retained debt securities are generally determined through reference to independent pricing information. The fair values of retained servicing rights and any other retained interests are determined based on the present value of expected future cash flows associated with those interests and by reference to market prices for similar assets.

Securitization structures and other financial vehicles oftentimes require the use of special-purpose trusts that are considered variable interest entities. A variable interest entity is included in the consolidated financial statements if the Company has the power to direct the activities that most significantly impact the variable interest entity’s economic performance and has the obligation to absorb losses or the right to receive benefits of the variable interest entity that could potentially be significant to that entity. The recognition or de-recognition in the Company’s consolidated financial statements of assets and liabilities held by variable interest entities is subject to the interpretation and application of complex accounting pronouncements or interpretations that require management to estimate and assess the relative significance of the Company’s financial interests in those entities and the degree to which the Company can influence the most important activities of the entities.

Goodwill and core deposit and other intangible assets

Goodwill represents the excess of the cost of an acquired entity over the fair value of the identifiable net assets acquired. Goodwill is not amortized, but rather is tested for impairment at least annually at the reporting unit level, which is either at the same level or one level below an operating segment. Other acquired intangible assets with finite lives, such as core deposit intangibles, are initially recorded at estimated fair value and are amortized over their estimated lives. Core deposit and other intangible assets are generally amortized using accelerated methods over estimated useful lives, which are generally three to seven years. The Company periodically assesses whether events or changes in circumstances indicate that the carrying amounts of core deposit and other intangible assets may be impaired.

Derivative financial instruments

The Company accounts for derivative financial instruments at fair value. If certain conditions are met, a derivative may be specifically designated as (i) a hedge of the exposure to changes in the fair value of a recognized asset or liability or an unrecognized firm commitment, (ii) a hedge of the exposure to variable cash flows of a forecasted transaction or (iii) a hedge of the foreign currency exposure of a net investment in a foreign operation, an unrecognized firm commitment, an available-for-sale security, or a foreign currency denominated forecasted transaction.

The Company utilizes interest rate swap agreements as part of the management of interest rate risk to modify the repricing characteristics of certain portions of its portfolios of earning assets and interest-bearing liabilities. For such agreements, amounts receivable or payable are recognized as accrued under the terms of the agreement and the net differential is recorded as an adjustment to interest income or expense of the related asset or liability. Interest rate swap agreements may be designated as either fair value hedges or cash flow hedges. In a fair value hedge, the fair values of the interest rate swap agreements and changes in the fair values of the hedged items are recorded in the Company’s Consolidated Balance Sheet with the corresponding gain or loss recognized in current earnings. The difference between changes in the fair values of interest rate swap agreements and the hedged items represents hedge ineffectiveness and is recorded in the same income statement line item that is used to present the earnings effect of the hedged item in the Consolidated Statement of Income. In a cash flow hedge, the derivative’s unrealized gain or loss is initially recorded as a component of other

comprehensive income and subsequently reclassified into earnings when the forecasted transaction affects earnings.

The Company utilizes commitments to sell real estate loans to hedge the exposure to changes in the fair value of real estate loans held for sale. Commitments to originate real estate loans to be held for sale and commitments to sell real estate loans are generally recorded in the Consolidated Balance Sheet at estimated fair value. Valuation adjustments made on these commitments are included in “mortgage banking revenues” in the Consolidated Statement of Income.

Derivative instruments not related to mortgage banking activities, including financial futures commitments and interest rate swap agreements, that do not satisfy the hedge accounting requirements are recorded at fair value and are generally classified as other assets or other liabilities with resultant changes in fair value being recognized in “trading account and other non-hedging derivative gains” in the Consolidated Statement of Income.

Revenue from contracts with customers

A significant amount of the Company’s revenues are derived from net interest income on financial assets and liabilities, mortgage banking revenues, trading account and other non-hedging derivative gains, investment securities gains, loan and letter of credit fees, income from bank-owned life insurance, and certain other revenues that are generally excluded from the scope of accounting guidance for revenue from contracts with customers. For other noninterest income revenue streams, the Company generally recognizes the expected amount of consideration as revenue when the performance obligations related to the services under the terms of a contract are satisfied. The Company’s contracts generally do not contain terms that necessitate significant judgment to determine the amount of revenue to recognize.

Stock-based compensation

Compensation expense is recognized over the vesting period of stock-based awards based on estimated grant date value, except that the recognition of compensation costs is accelerated for stock-based awards granted to retirement-eligible employees and employees who will become retirement-eligible prior to full vesting of the award because the Company’s incentive compensation plan allows for vesting at the time an employee retires.

Income taxes

Deferred tax assets and liabilities are recognized for the future tax effects attributable to differences between the financial statement value of existing assets and liabilities and their respective tax bases and carryforwards. Deferred tax assets and liabilities are measured using enacted tax rates and laws.

The Company evaluates uncertain tax positions using the two-step process required by GAAP. The first step requires a determination of whether it is more likely than not that a tax position will be sustained upon examination, including resolution of any related appeals or litigation processes, based on the technical merits of the position. Under the second step, a tax position that meets the more-likely-than-not recognition threshold is measured at the largest amount of benefit that is greater than fifty percent likely of being realized upon ultimate settlement.

The Company accounts for its investments in qualified affordable housing projects using the proportional amortization method. Under that method, the Company amortizes the initial cost of the investment in proportion to the tax credits and other tax benefits received and recognizes the net investment performance in the income statement as a component of income tax expense.

Earnings per common share

Basic earnings per common share exclude dilution and are computed by dividing income available to common shareholders by the weighted-average number of common shares outstanding (exclusive of shares represented by the unvested portion of restricted stock and restricted stock unit grants) and common shares issuable under deferred compensation arrangements during the period. Diluted earnings per common share reflect shares represented by the unvested portion of restricted stock and restricted stock unit grants and the potential dilution that could occur if securities or other contracts to issue common stock were exercised or converted into common stock or resulted in the issuance of common stock that then shared in earnings. Proceeds assumed to have been received on such exercise or conversion are assumed to be used to purchase shares of M&T common stock at the average market price during the period, as required by the “treasury stock method” of accounting.

GAAP requires that unvested share-based payment awards that contain nonforfeitable rights to dividends or dividend equivalents (whether paid or unpaid) shall be considered participating securities and shall be included in the computation of earnings per common share pursuant to the two-class method. The Company has issued stock-based compensation awards in the form of restricted stock and restricted stock units that contain such rights and, accordingly, the Company’s earnings per common share are calculated using the two-class method.

Treasury stock

Repurchases of shares of M&T common stock are recorded at cost as a reduction of shareholders’ equity. Reissuances of shares of treasury stock are recorded at average cost.

Revenue from contracts with customers (Tables)

12 Months Ended

Dec. 31, 2023

ASU 2014-09 [Member]

Summary of Sources of Noninterest Income that are Subject to Revenue Recognition Guidance

The following tables summarize sources of the Company’s noninterest income during 2023, 2022 and 2021 that are subject to the revenue recognition guidance.


(Dollars in millions)	Commercial Bank		Retail Bank		Institutional Services and Wealth Management		Total
Year Ended December 31, 2023
Classification in Consolidated Statement of Income
Service charges on deposit accounts	$	144	$	330	$	1	$	475
Trust income		2		—		678		680
Brokerage services income		6		—		96		102
Other revenues from operations:
Merchant discount and credit card interchange fees		77		84		—		161
Other		28		30		8		66
	$	257	$	444	$	783	$	1,484

Year Ended December 31, 2022
Classification in Consolidated Statement of Income
Service charges on deposit accounts	$	130	$	317	$	—	$	447
Trust income		—		—		741		741
Brokerage services income		5		—		83		88
Other revenues from operations:
Merchant discount and credit card interchange fees		73		86		—		159
Other		24		28		38		90
	$	232	$	431	$	862	$	1,525

Year Ended December 31, 2021
Classification in Consolidated Statement of Income
Service charges on deposit accounts	$	115	$	287	$	—	$	402
Trust income		—		—		645		645
Brokerage services income		2		—		61		63
Other revenues from operations:
Merchant discount and credit card interchange fees		58		73		—		131
Other		13		30		40		83
	$	188	$	390	$	746	$	1,324

Goodwill and Other Intangible Assets - Total Amortizing Intangible Assets (Detail) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 261	$ 261
Accumulated Amortization	114	52
Net Carrying Amount	147	209
Core Deposit [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	218	218
Accumulated Amortization	90	41
Net Carrying Amount	128	177
Other [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	43	43
Accumulated Amortization	24	11
Net Carrying Amount	$ 19	$ 32

Pension plans and other postretirement benefits (Tables)

12 Months Ended

Dec. 31, 2023

Retirement Benefits [Abstract]

Net Periodic Pension Expense for Defined Benefit Plans

Net periodic pension expense for defined benefit plans consisted of the following:


	Year Ended December 31,
(Dollars in millions)	2023			2022			2021
Service cost	$	11		$	18		$	20
Interest cost on benefit obligation		115			82			62
Expected return on plan assets		(201	)		(188	)		(143	)
Amortization of prior service cost		—			1			1
Recognized net actuarial (gain) loss		(2	)		20			89
Net periodic pension (benefit) cost	$	(77	)	$	(67	)	$	29

Net other postretirement benefits expense for defined benefit plans consisted of the following:


	Year Ended December 31,
(Dollars in millions)	2023			2022			2021
Service cost	$	2		$	3		$	1
Interest cost on benefit obligation		3			2			1
Amortization of prior service credit		(2	)		(3	)		(5	)
Recognized net actuarial gain		(3	)		(1	)		(1	)
Net other postretirement (benefit) cost	$	—		$	1		$	(4	)

Data Relating to Funding Position of Defined Benefit Plans

Data relating to the funding position of the defined benefit plans were as follows:


	Pension Benefits						Other Postretirement Benefits
(Dollars in millions)	2023			2022			2023			2022
Change in benefit obligation:
Benefit obligation at beginning of year	$	2,379		$	2,420		$	60		$	52
Service cost		11			18			2			3
Interest cost		115			82			3			2
Plan participants’ contributions		—			—			1			2
Actuarial (gain) loss		13			(636	)		(5	)		(22	)
Plan amendment		—			—			—			13
Business combinations		—			633			—			15
Medicare Part D reimbursement		—			—			—			1
Benefits paid		(149	)		(138	)		(4	)		(6	)
Benefit obligation at end of year		2,369			2,379			57			60
Change in plan assets:
Fair value of plan assets at beginning of year		2,942			2,596			—			—
Actual return on plan assets		334			(386	)		—			—
Employer contributions		18			14			3			3
Business combinations		—			856			—			—
Plan participants’ contributions		—			—			1			2
Medicare Part D reimbursement		—			—			—			1
Benefits paid		(149	)		(138	)		(4	)		(6	)
Fair value of plan assets at end of year		3,145			2,942			—			—
Funded status	$	776		$	563		$	(57	)	$	(60	)
Prepaid asset recognized in the Consolidated Balance Sheet	$	922		$	715		$	—		$	—
Accrued liability recognized in the Consolidated Balance Sheet		(146	)		(152	)		(57	)		(60	)
Net accrued asset (liability) recognized in the Consolidated Balance Sheet	$	776		$	563		$	(57	)	$	(60	)
Amounts recognized in accumulated other comprehensive income were:
Net loss (gain)	$	191		$	309		$	(37	)	$	(35	)
Net prior service cost (credit)		—			—			1			(1	)
Pre-tax adjustment to accumulated other comprehensive income		191			309			(36	)		(36	)
Taxes		(49	)		(80	)		9			9
Net adjustment to accumulated other comprehensive income	$	142		$	229		$	(27	)	$	(27	)

Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income

The table below reflects the changes in plan assets and benefit obligations recognized in other comprehensive income related to the Company’s postretirement benefit plans.


(Dollars in millions)	Pension Plans			Other Postretirement Benefit Plans			Total
2023
Net gain	$	(120	)	$	(5	)	$	(125	)
Amortization of prior service credit		—			2			2
Amortization of actuarial gain		2			3			5
Total recognized in other comprehensive income, pre-tax	$	(118	)	$	—		$	(118	)
2022
Net gain	$	(62	)	$	(22	)	$	(84	)
Net prior service cost		—			13			13
Amortization of prior service (cost) credit		(1	)		3			2
Amortization of actuarial (loss) gain		(20	)		2			(18	)
Total recognized in other comprehensive income, pre-tax	$	(83	)	$	(4	)	$	(87	)

Assumed Weighted-Average Rates Used to Determine Benefit Obligations

The assumed weighted-average rates used to determine benefit obligations at December 31 were:


	Pension Benefits						Other Postretirement Benefits
	2023			2022			2023			2022
Discount rate		5.00	%		5.00	%		5.00	%		5.00	%
Rate of increase in future compensation levels		3.32			3.33			—			—

Assumed Weighted-Average Rates Used to Determine Net Benefit Expense

The assumed weighted-average rates used to determine net benefit expense for the years ended December 31 were:


	Pension Benefits									Other Postretirement Benefits
	2023			2022			2021			2023			2022			2021
Discount rate		5.00	%		2.75	%		2.50	%		5.00	%		2.75	%		2.50	%
Long-term rate of return on plan assets		6.25			6.25			6.25			—			—			—
Rate of increase in future compensation levels		3.33			3.35			3.37			—			—			—

Fair Values of Company's Pension Plan Assets by Asset Category

The fair values of the Company’s pension plan assets at December 31, 2023 and 2022, by asset category, were as follows:


	Fair Value Measurement of Plan Assets At December 31, 2023
(Dollars in millions)	Total		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Asset category:
Money-market investments	$	65	$	41	$	24	$	—
Equity securities:
M&T		112		112		—		—
Domestic (a)		512		512		—		—
International (b)		17		17		—		—
Mutual funds:
Domestic (a)		307		307		—		—
International (b)		501		501		—		—
		1,449		1,449		—		—
Debt securities:
Corporate (c)		227		—		227		—
Government		276		—		276		—
International		6		—		6		—
Mutual funds:
Domestic (d)		450		450		—		—
		959		450		509		—
Other:
Diversified mutual fund		110		110		—		—
Real estate partnerships		29		7		—		22
Private equity / debt		235		—		—		235
Hedge funds		285		107		—		178
Guaranteed deposit fund		9		—		—		9
		668		224		—		444
Total (e)	$	3,141	$	2,164	$	533	$	444


	Fair Value Measurement of Plan Assets At December 31, 2022
(Dollars in millions)	Total		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Asset category:
Money-market investments	$	90	$	52	$	38	$	—
Equity securities:
M&T		118		118		—		—
Domestic (a)		450		450		—		—
International (b)		19		19		—		—
Mutual funds:
Domestic (a)		279		279		—		—
International (b)		477		477		—		—
		1,343		1,343		—		—
Debt securities:
Corporate (c)		200		—		200		—
Government		236		—		236		—
International		15		—		15		—
Mutual funds:
Domestic (d)		422		422		—		—
		873		422		451		—
Other:
Diversified mutual fund		108		108		—		—
Real estate partnerships		27		7		—		20
Private equity / debt		211		—		—		211
Hedge funds		276		109		—		167
Guaranteed deposit fund		10		—		—		10
		632		224		—		408
Total (e)	$	2,938	$	2,041	$	489	$	408

(a)

This category is mainly comprised of equities of companies primarily within the small-cap, mid-cap and large-cap sectors of the U.S. economy and range across diverse industries.

(b)

This category is comprised of equities in companies primarily within the mid-cap and large-cap sectors of international markets mainly in developed and emerging markets in Europe and the Pacific Rim.

(c)

This category represents investment grade bonds of U.S. issuers from diverse industries.

(d)

Approximately 73% of the mutual funds were invested in investment grade bonds and 27% in high-yielding bonds at each of December 31, 2023 and 2022. The holdings within the funds were spread across diverse industries.

(e)

Excludes dividends and interest receivable totaling $4 million at each of December 31, 2023 and 2022.

Changes in Level 3 Pension Plan Assets Measured at Fair Value on Recurring Basis

The changes in Level 3 pension plan assets measured at estimated fair value on a recurring basis during the year ended December 31, 2023 were as follows:


(Dollars in millions)	Balance – January 1, 2023		Net Purchases (Sales)		Realized/ Unrealized Gains (Losses)			Balance – December 31, 2023
Real estate partnerships	$	20	$	2	$	—		$	22
Private equity/debt		211		12		12			235
Hedge funds		167		—		11			178
Guaranteed deposit fund		10		—		(1	)		9
Total	$	408	$	14	$	22		$	444

Defined Benefit Plan Estimated Future Benefit Payments

Estimated benefits expected to be paid in future years related to the Company’s defined benefit pension and other postretirement benefits plans are as follows:


(Dollars in millions)	Pension Benefits		Other Postretirement Benefits
Year ending December 31:
2024	$	150	$	4
2025		154		4
2026		157		4
2027		160		4
2028		164		4
2029 through 2033		838		19

Pension Plans and Other Postretirement Benefits - Fair Values of Company's Pension Plan Assets by Asset Category (Parenthetical) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Defined Benefit Plan Disclosure [Line Items]
Interest and dividend receivable on plan assets	$ 4	$ 4
High-Yielding Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Investment in mutual funds	27.00%	27.00%
Investment Grade Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Investment in mutual funds	73.00%	73.00%

Loans and Leases - Minimum Future Lease Payments to be Received from Lease Financings (Detail) $ in Millions	Dec. 31, 2023 USD ($)
Receivables [Abstract]
2024	$ 823
2025	677
2026	468
2027	290
2028	136
Later years	94
Total	$ 2,488

Other Income and Other Expense - Other Income and Other Expense (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Other revenues from operations:
Credit-related fee income	$ 151	$ 130	$ 91
Credit card interchange fee income			70
Merchant discount fee income			61
Other costs of operations:
Amortization of capitalized mortgage servicing rights	131	97	$ 90
Charitable contributions		178
CIT [Member]
Other revenues from operations:
Gain on divestiture	$ 225
MTLA [Member]
Other revenues from operations:
Gain on divestiture		$ 136

Premises and Equipment - Summary of Lease Costs for Operating Leases, Cash Paid Toward Lease Liabilities, and Weighted-Average Remaining Term and Discount Rates of Operating Leases (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Lease cost
Operating lease cost	$ 154	$ 139	$ 102
Short-term lease cost		8
Variable lease cost	4	4	4
Total lease cost	158	151	106
Other information
Right-of-use assets obtained in exchange for new operating lease liabilities	134	138	58
Right-of-use assets acquired in business combination		226
Cash paid toward lease liabilities	$ 158	$ 143	$ 107
Weighted-average remaining lease term	7 years	7 years	6 years
Weighted-average discount rate	3.37%	2.97%	2.51%

Investment Securities - Amortized Cost and Estimated Fair Value of Investment Securities (Detail) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Schedule Of Amortized Cost And Estimated Fair Value Of Investment Securities [Line Items]
Investment securities available for sale, amortized cost	$ 10,691	$ 11,193
Investment securities available for sale, gross unrealized gains		1
Investment securities available for sale, gross unrealized losses	251	445
Investment securities available for sale, estimated fair value	10,440	10,749
Amortized cost for held to maturity	15,330	13,530
Gross unrealized gains for held to maturity	13	10
Gross unrealized losses for held to maturity	1,035	1,165
Estimated fair value for held to maturity	14,308	12,375
Equity and other securities, Amortized Cost	1,125	934
Equity securities, Gross Unrealized Gains	5	2
Equity securities, Gross Unrealized Losses	3	4
Equity and other securities, Estimated Fair Value	1,127	932
Other securities, Amortized cost	859	781
Other securities, Estimated fair value	859	781
Total debt securities Amortized cost	26,021	24,723
Total debt securities Gross unrealized gains	13	11
Total debt securities Gross unrealized losses	1,286	1,610
Total debt securities Estimated fair value	24,748	23,124
Readily marketable securities Amortized cost	266	153
Readily marketable securities Gross unrealized gains	5	2
Readily marketable securities Gross unrealized losses	3	4
Readily marketable securities Estimated fair value	268	151
U.S. Treasury and Federal Agencies [Member]
Schedule Of Amortized Cost And Estimated Fair Value Of Investment Securities [Line Items]
Investment securities available for sale, amortized cost	7,818	7,914
Investment securities available for sale, gross unrealized losses	113	243
Investment securities available for sale, estimated fair value	7,705	7,671
Amortized cost for held to maturity	1,005	1,054
Gross unrealized losses for held to maturity	31	46
Estimated fair value for held to maturity	974	1,008
Obligations of States and Political Subdivisions [Member]
Schedule Of Amortized Cost And Estimated Fair Value Of Investment Securities [Line Items]
Amortized cost for held to maturity	2,501	2,577
Gross unrealized losses for held to maturity	67	117
Estimated fair value for held to maturity	2,434	2,460
Commercial [Member]
Schedule Of Amortized Cost And Estimated Fair Value Of Investment Securities [Line Items]
Investment securities available for sale, amortized cost	425	595
Investment securities available for sale, gross unrealized losses	9	21
Investment securities available for sale, estimated fair value	416	574
Amortized cost for held to maturity	2,033	912
Gross unrealized losses for held to maturity	130	103
Estimated fair value for held to maturity	1,903	809
Residential [Member]
Schedule Of Amortized Cost And Estimated Fair Value Of Investment Securities [Line Items]
Investment securities available for sale, amortized cost	2,272	2,501
Investment securities available for sale, gross unrealized losses	118	171
Investment securities available for sale, estimated fair value	2,154	2,330
Amortized cost for held to maturity	9,747	8,935
Gross unrealized gains for held to maturity	4	1
Gross unrealized losses for held to maturity	802	891
Estimated fair value for held to maturity	8,949	8,045
Other Debt Securities [Member]
Schedule Of Amortized Cost And Estimated Fair Value Of Investment Securities [Line Items]
Investment securities available for sale, amortized cost	176	183
Investment securities available for sale, gross unrealized gains		1
Investment securities available for sale, gross unrealized losses	11	10
Investment securities available for sale, estimated fair value	165	174
Amortized cost for held to maturity	2
Estimated fair value for held to maturity	2	2
Privately Issued [Member]
Schedule Of Amortized Cost And Estimated Fair Value Of Investment Securities [Line Items]
Amortized cost for held to maturity	42	50
Gross unrealized gains for held to maturity	9	9
Gross unrealized losses for held to maturity	5	8
Estimated fair value for held to maturity	$ 46	$ 51

Earnings Per Common Share - Additional Information (Detail) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Earnings Per Share [Abstract]
Antidilutive securities excluded from computation of earnings per share	1,834,000	453,000	461,000

Income taxes

12 Months Ended

Dec. 31, 2023

Income Tax Disclosure [Abstract]

Income taxes

14. Income taxes

The components of income tax expense were as follows:


	Year Ended December 31,
(Dollars in millions)	2023			2022			2021
Current:
Federal	$	580		$	367		$	332
State and local		228			143			85
Total current		808			510			417
Deferred:
Federal		(64	)		(18	)		72
State and local		(33	)		(12	)		15
Total deferred		(97	)		(30	)		87
Amortization of investments in qualified affordable housing projects		167			140			92
Total income taxes applicable to pre-tax income	$	878		$	620		$	596

The Company files a consolidated federal income tax return reflecting taxable income earned by all domestic subsidiaries. In prior years, applicable federal tax law allowed certain financial institutions the option of deducting as bad debt expense for tax purposes amounts in excess of actual losses. In accordance with GAAP, such financial institutions were not required to provide deferred income taxes on such excess. Recapture of the excess tax bad debt reserve established under the previously allowed method will result in taxable income if M&T Bank fails to maintain bank status as defined in the Internal Revenue Code or charges are made to the reserve for other than bad debt losses. At December 31, 2023, M&T Bank’s tax bad debt reserve for which no federal income taxes have been provided was $137 million. No actions are planned that would cause this reserve to become wholly or partially taxable.

Total income taxes differed from the amount computed by applying the statutory federal income tax rate to pre-tax income as follows:


	Year Ended December 31,
(Dollars in millions)	2023			2022			2021
Income taxes at statutory federal income tax rate	$	760		$	548		$	516
Increase (decrease) in taxes:
Tax-exempt income		(51	)		(37	)		(21	)
State and local income taxes, net of federal income tax effect		161			110			101
Qualified affordable housing project tax benefits, net		(26	)		(22	)		(15	)
Other		34			21			15
	$	878		$	620		$	596

Deferred tax assets (liabilities) were comprised of the following at December 31:


(Dollars in millions)	2023			2022			2021
Losses on loans and other assets	$	686		$	641		$	396
Operating lease liabilities		182			183			110
Postretirement and other employee benefits		47			—			32
Incentive and other compensation plans		30			34			25
Unrealized losses		64			115			—
Interest on loans		42			54			—
Losses on cash flow hedges		52			87			—
Stock-based compensation		54			51			33
Other		153			81			52
Gross deferred tax assets		1,310			1,246			648
Right-of-use assets and other leasing transactions		(336	)		(367	)		(249	)
Unrealized gains		—			—			(27	)
Retirement benefits		(198	)		(88	)		(46	)
Capitalized servicing rights		(38	)		(51	)		(53	)
Postretirement and other employee benefits		—			(29	)		—
Depreciation and amortization		(157	)		(155	)		(93	)
Interest on loans		—			—			(7	)
Gains on cash flow hedges		—			—			(23	)
Other		(59	)		(69	)		(88	)
Gross deferred tax liabilities		(788	)		(759	)		(586	)
Net deferred tax asset	$	522		$	487		$	62

The Company believes that it is more likely than not that the deferred tax assets will be realized through taxable earnings or alternative tax strategies.

The income tax credits shown in the statement of income of M&T in note 26 arise principally from operating losses before dividends from subsidiaries.

A reconciliation of the beginning and ending amount of unrecognized tax benefits follows:


(Dollars in millions)	Federal, State and Local Tax			Accrued Interest			Unrecognized Income Tax Benefits
Gross unrecognized tax benefits at January 1, 2021	$	49		$	8		$	56
Increases as a result of tax positions taken in prior years		—			3			3
Decreases as a result of tax positions taken in prior years		(11	)		(3	)		(14	)
Gross unrecognized tax benefits at December 31, 2021		38			8			45
Increases as a result of tax positions taken in prior years		—			3			3
Unrecognized tax benefits assumed in a business combination		3			1			5
Decreases as a result of tax positions taken in prior years		(11	)		(4	)		(15	)
Gross unrecognized tax benefits at December 31, 2022		30			8			38
Increases as a result of tax positions taken in prior years		5			1			6
Decreases as a result of tax positions taken in prior years		(13	)		(3	)		(16	)
Gross unrecognized tax benefits at December 31, 2023	$	22		$	6		$	28
Less: Federal, state and local income tax benefits								(6	)
Net unrecognized tax benefits at December 31, 2023 that, if recognized, would impact the effective income tax rate							$	22

The Company’s policy is to recognize interest and penalties, if any, related to unrecognized tax benefits in income taxes in the Consolidated Statement of Income. The Company’s federal, state and local income tax returns are routinely subject to examinations from various governmental taxing authorities. Such examinations may result in challenges to the tax return treatment applied by the

Company to specific transactions. Management believes that the assumptions and judgment used to record tax-related assets or liabilities have been appropriate. Should determinations rendered by tax authorities ultimately indicate that management’s assumptions were inappropriate, the result and adjustments required could have a material effect on the Company’s results of operations. Examinations by the Internal Revenue Service of the Company’s federal income tax returns have been largely concluded through 2021, although under statute the income tax returns from 2020 through 2022 could be adjusted. The Company also files income tax returns in over forty states and numerous local jurisdictions. Substantially all material state and local matters have been concluded for years through 2014. It is not reasonably possible to estimate when examinations for any subsequent years will be completed.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480990/946-20-50-13

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(h)(2))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480678/235-10-S99-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org//740/tableOfContent

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 14
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482685/740-10-50-14

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 21
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482685/740-10-50-21

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 270
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482526/740-270-50-1

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 17
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482685/740-10-50-17

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SAB TOPIC 6.I.5.Q1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479360/740-10-S99-1

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SAB Topic 11.C)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479360/740-10-S99-2

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482603/740-30-50-2

+ Details

Income Taxes - Additional Information (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($) State
Income Tax Disclosure [Abstract]
Tax bad debt reserve \| $	$ 137
Number of state and local jurisdictions where company files income tax returns \| State	40

Parent company financial statements (Tables)

12 Months Ended

Dec. 31, 2023

Condensed Financial Information Disclosure [Abstract]

Condensed Balance Sheet


	December 31,
(Dollars in millions)	2023		2022
Assets
Cash in subsidiary bank	$	176	$	130
Due from consolidated bank subsidiaries:
Money-market savings		3,223		1,690
Current income tax receivable		5		4
Total due from consolidated bank subsidiaries		3,228		1,694
Investments in consolidated subsidiaries:
Banks		26,290		25,005
Other		391		380
Investments in trust preferred entities (note 20)		22		22
Other assets		100		93
Total assets	$	30,207	$	27,324
Liabilities
Accrued expenses and other liabilities	$	152	$	172
Long-term borrowings		3,098		1,834
Total liabilities		3,250		2,006
Shareholders’ equity		26,957		25,318
Total liabilities and shareholders’ equity	$	30,207	$	27,324

Condensed Statement of Income


	Year Ended December 31,
(Dollars in millions, except per share)	2023			2022			2021
Income
Dividends from consolidated subsidiaries	$	2,041		$	2,508		$	1,025
Income from Bayview Lending Group LLC		20			30			30
Other income		6			(7	)		3
Total income		2,067			2,531			1,058
Expense
Interest on short-term borrowings		—			6			—
Interest on long-term borrowings		182			57			24
Other expense		40			50			36
Total expense		222			113			60
Income before income taxes and equity in undistributed income of subsidiaries		1,845			2,418			998
Income tax credits		49			22			6
Income before equity in undistributed income of subsidiaries		1,894			2,440			1,004
Equity in undistributed income of subsidiaries
Net income of subsidiaries		2,888			2,060			1,880
Less: dividends received		(2,041	)		(2,508	)		(1,025	)
Equity in undistributed income of subsidiaries		847			(448	)		855
Net income	$	2,741		$	1,992		$	1,859
Net income per common share
Basic	$	15.85		$	11.59		$	13.81
Diluted		15.79			11.53			13.80

Condensed Statement of Cash Flow

Condensed Statement of Cash Flows


	Year Ended December 31,
(Dollars in millions)	2023			2022			2021
Cash flows from operating activities
Net income	$	2,741		$	1,992		$	1,859
Adjustments to reconcile net income to net cash provided by operating activities:
Equity in undistributed income of subsidiaries		(847	)		448			(855	)
Provision for deferred income taxes		(5	)		7			10
Net change in accrued income and expense		32			8			(23	)
Net cash provided by operating activities		1,921			2,455			991
Cash flows from investing activities
Net investment in consolidated subsidiaries		(1	)		54			(199	)
Acquisition, net of cash consideration		—			538			—
Other, net		(41	)		24			(3	)
Net cash provided (used) by investing activities		(42	)		616			(202	)
Cash flows from financing activities
Repayment of short-term borrowings assumed in acquisition		—			(500	)		—
Proceeds from long-term borrowings		1,998			499			—
Payments on long-term borrowings		(750	)		—			—
Purchases of treasury stock		(594	)		(1,800	)		—
Dividends paid — common		(868	)		(784	)		(580	)
Dividends paid — preferred		(100	)		(97	)		(68	)
Proceeds from issuance of Series I preferred stock		—			—			495
Other, net		14			2			(7	)
Net cash used by financing activities		(300	)		(2,680	)		(160	)
Net increase in cash and cash equivalents		1,579			391			629
Cash and cash equivalents at beginning of year		1,820			1,429			800
Cash and cash equivalents at end of year	$	3,399		$	1,820		$	1,429
Supplemental disclosure of cash flow information
Interest received during the year	$	6		$	1		$	1
Interest paid during the year		135			49			20
Income taxes received during the year		43			28			53

Acquisition and Divestitures - Summary of Merger Related Expenses (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outside data processing and software	$ 437	$ 376	$ 292
Professional and other services	413	509	379
Advertising and marketing	$ 108	90	64
Peoples United Financial Inc [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Salaries and employee benefits		102
Equipment and net occupancy		7
Outside data processing and software		5	1
Professional and other services		72	37
Advertising and marketing		9	1
Other cost of operations		143	5
Other Expenses, Total		$ 338	$ 44

Premises and Equipment - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Property Plant And Equipment Capitalized Interest Costs [Abstract]
Operating lease liabilities	$ 717	$ 709
Operating Lease Liability Statement Of Financial Position Extensible List	Accrued interest and other liabilities	Accrued interest and other liabilities
Period of noncancelable operating lease in years	18 years

Other income and other expense (Tables)

12 Months Ended

Dec. 31, 2023

Other Income and Expenses [Abstract]

Other Income and Other Expense

The following items, which exceeded 1% of total interest income and other income in the respective period, were included in either "other revenues from operations" or "other costs of operations" in the Consolidated Statement of Income:


	Year Ended December 31,
(Dollars in millions)	2023		2022		2021
Other revenues from operations:
Gain on divestiture of CIT	$	225
Credit-related fee income		151	$	130	$	91
Gain on divestiture of MTIA				136
Credit card interchange fee income						70
Merchant discount fee income						61
Other costs of operations:
Amortization of capitalized mortgage servicing rights		131		97		90
Charitable contributions				178

Consolidated Balance Sheet - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Assets
Cash and due from banks	$ 1,731	$ 1,517
Interest-bearing deposits at banks	28,069	24,959
Federal funds sold		3
Trading account	106	118
Investment securities
Available for sale (cost: $10,69] at December 31, 2023 ; $11,193 at December 31, 2022)	10,440	10,749
Held to maturity (fair value: $14,308 at December 31, 2023; $12,375 at December 31, 2022)	15,330	13,530
Equity and other securities (cost: : $1,125 at December 31, 2023; $934 at December 31, 2022)	1,127	932
Total investment securities	26,897	25,211
Loans receivable	134,936	132,074
Unearned discount	(868)	(510)
Loans and leases, net of unearned discount	134,068	131,564
Allowance for credit losses	(2,129)	(1,925)
Loans and leases, net	131,939	129,639
Premises and equipment	1,739	1,654
Goodwill	8,465	8,490
Core deposit and other intangible assets	147	209
Accrued interest and other assets	9,171	8,930
Total assets	208,264	200,730
Liabilities
Noninterest-bearing deposits	49,294	65,502
Savings and interest-checking deposits	93,221	87,911
Time deposits	20,759	10,102
Total deposits	163,274	163,515
Short-term borrowings	5,316	3,555
Accrued interest and other liabilities	4,516	4,377
Long-term borrowings	8,201	3,965
Total liabilities	181,307	175,412
Shareholders' equity
Preferred stock, $1.00 par, 20,000,000 shares authorized; Issued and outstanding: Liquidation preference of [$1,000 per share: 350,000] shares at December 31, 2023 and December 31, 2022; Liquidation preference of $10,000 per share: 140,000 shares at December 31, 2023 and December 31,2022; Liquidation preference of $25 per share: 10,000,000 shares at December 31, 2023 and December 31, 2022	2,011	2,011
Common stock, $.50 par, 250,000,000 shares authorized, 179,436,779 shares issued at December 31, 2023 and December 31, 2022	90	90
Common stock issuable, [12,217] shares at December 31, 2023; 14,031 shares at December 31, 2022	1	1
Additional paid-in capital	10,020	10,002
Retained earnings	17,524	15,754
Accumulated other comprehensive income (loss), net	(459)	(790)
Treasury stock - common, at cost - [13,300,298] shares at December 31, 2023; 10,165,419 shares at December 31, 2022	(2,230)	(1,750)
Total shareholders’ equity	26,957	25,318
Total liabilities and shareholders’ equity	$ 208,264	$ 200,730

Stock-Based Compensation Plans - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	$ 118,000	$ 111,000	$ 85,000
Recognized income tax benefits related to stock-based compensation	$ 24,000	$ 26,000	$ 16,000
Shares under equity incentive compensation plan for future grant	4,218,093	1,650,696
Stock Options Outstanding, Granted	179,551	138,825	178,441
Weighted average grant date fair value of options granted	$ 9,000	$ 6,000	$ 5,000
Directors’ Stock Compensation Programs [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares issuable under deferred compensation plans	1,979	2,306
Shares issued in connection with deferred compensation plans	27,027	22,068
Deferred Bonus Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares issuable under deferred compensation plans	10,238	11,725
Stock Purchase Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares under equity incentive compensation plan for future grant	1,972,627
Shares issued	90,575	75,232	95,147
Cash received from exercise of stock options	$ 13,000	$ 11,000	$ 11,000
Restricted Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period	3 years	3 years	3 years
Shares issued	0	0	0
Unrecognized compensation cost expected to be recognized over a weighted-average period (in years)	1 year
Restricted Stock Units (RSUs) [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares issued	752,534	548,926	636,956
Weighted-average grant date fair value	$ 116,000	$ 93,000	$ 84,000
Unrecognized compensation cost related to non-vested awards	$ 42,000
Stock Option Awards [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period	3 years
Stock options exercisable period, maximum	10 years
Cash realized from exercise of stock options	$ 32,000	$ 37,000	$ 305

Derivative Financial Instruments - Notional Amount of Interest Rate Swap Agreements Outstanding Maturity (Detail) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Derivative Instruments And Hedging Activities Disclosures [Line Items]
2024	$ 3,158
2025	10,369
2026	10,450
2027	1,000
2028	1,000
2033	1,000
Total	$ 26,977	$ 17,400

Acquisition and Divestitures - Additional Information (Details) - USD ($)				9 Months Ended	12 Months Ended
	Apr. 29, 2023	Oct. 30, 2022	Apr. 01, 2022	Dec. 31, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Oct. 31, 2022	Dec. 31, 2020
Business Acquisition [Line Items]
ACL for non-PCD loan and leases			$ 242,000,000
Initial estimate of expected credit losses			99,000,000
Goodwill				$ 8,490,000,000	$ 8,465,000,000	$ 8,490,000,000
Revenues					9,643,000,000	8,179,000,000	$ 5,992,000,000
Net income (loss)					2,741,000,000	1,992,000,000	1,859,000,000
Assets				200,730,000,000	208,264,000,000	200,730,000,000
Shareholders’ equity				25,318,000,000	26,957,000,000	25,318,000,000	17,903,000,000		$ 16,187,000,000
Trust Income [Member]
Business Acquisition [Line Items]
Revenue from contract with customer					680,000,000	741,000,000	645,000,000
Collective Investment Trust [Member] \| Trust Income [Member]
Business Acquisition [Line Items]
Gain (loss) on sale of subsidiary, pre-tax	$ 225,000,000
Gain (loss) on sale of subsidiary after-tax effect	$ 157,000,000
Revenue from contract with customer					60,000,000	165,000,000	151,000,000
Common Stock [Member]
Business Acquisition [Line Items]
Shareholders’ equity				90,000,000	$ 90,000,000	$ 90,000,000	80,000,000		$ 80,000,000
Minimum [Member]
Business Acquisition [Line Items]
Amortization period					3 years
Maximum [Member]
Business Acquisition [Line Items]
Amortization period					7 years
Peoples United Financial Inc [Member]
Business Acquisition [Line Items]
Business combination, market value			$ 8,400,000,000
Common stock, price per share			$ 164.66
ACL for non-PCD loan and leases			$ 242,000,000
Goodwill			3,908,000,000
Core deposit and other intangible assets			$ 261,000,000
Revenues				1,600,000,000
Net income (loss)				$ 165,000,000
Peoples United Financial Inc [Member] \| Financial Service [Member]
Business Acquisition [Line Items]
Merger-related expenses					$ 0
Peoples United Financial Inc [Member] \| Common Stock [Member]
Business Acquisition [Line Items]
Common stock issued in transaction			50,325,004
Peoples United Financial Inc [Member] \| Core Deposit and Other Intangible Assets [Member] \| Minimum [Member]
Business Acquisition [Line Items]
Amortization period			3 years
Peoples United Financial Inc [Member] \| Core Deposit and Other Intangible Assets [Member] \| Maximum [Member]
Business Acquisition [Line Items]
Amortization period			7 years
M T [Member]
Business Acquisition [Line Items]
Common stock, price per share			$ 0.118
M&T Insurance Agency, Inc [Member]
Business Acquisition [Line Items]
Revenues		$ 34,000,000					$ 37,000,000
Gain (loss) on sale of subsidiary, pre-tax					136,000,000
Gain (loss) on sale of subsidiary after-tax effect					$ 98,000,000
Assets								$ 18,000,000
Shareholders’ equity								$ 6,000,000

Investment securities (Tables)

12 Months Ended

Dec. 31, 2023

Investments, Debt and Equity Securities [Abstract]

Amortized Cost and Estimated Fair Value of Investment Securities

The amortized cost and estimated fair value of investment securities were as follows:


(Dollars in millions)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
December 31, 2023
Investment securities available for sale:
U.S. Treasury and federal agencies	$	7,818	$	—	$	113	$	7,705
Mortgage-backed securities:
Government issued or guaranteed:
Commercial		425		—		9		416
Residential		2,272		—		118		2,154
Other debt securities		176		—		11		165
		10,691		—		251		10,440
Investment securities held to maturity:
U.S. Treasury and federal agencies		1,005		—		31		974
Obligations of states and political subdivisions		2,501		—		67		2,434
Mortgage-backed securities:
Government issued or guaranteed:
Commercial		2,033		—		130		1,903
Residential		9,747		4		802		8,949
Privately issued		42		9		5		46
Other debt securities		2		—		—		2
		15,330		13		1,035		14,308
Total debt securities	$	26,021	$	13	$	1,286	$	24,748
Equity and other securities:
Readily marketable equity — at fair value	$	266	$	5	$	3	$	268
Other — at cost		859		—		—		859
Total equity and other securities	$	1,125	$	5	$	3	$	1,127

December 31, 2022
Investment securities available for sale:
U.S. Treasury and federal agencies	$	7,914	$	—	$	243	$	7,671
Mortgage-backed securities:
Government issued or guaranteed:
Commercial		595		—		21		574
Residential		2,501		—		171		2,330
Other debt securities		183		1		10		174
		11,193		1		445		10,749
Investment securities held to maturity:
U.S. Treasury and federal agencies		1,054		—		46		1,008
Obligations of states and political subdivisions		2,577		—		117		2,460
Mortgage-backed securities:
Government issued or guaranteed:
Commercial		912		—		103		809
Residential		8,935		1		891		8,045
Privately issued		50		9		8		51
Other debt securities		2		—		—		2
		13,530		10		1,165		12,375
Total debt securities	$	24,723	$	11	$	1,610	$	23,124
Equity and other securities:
Readily marketable equity — at fair value	$	153	$	2	$	4	$	151
Other — at cost		781		—		—		781
Total equity and other securities	$	934	$	2	$	4	$	932

Investment Ratings of All Privately Issued Mortgage-Backed Securities and Other Debt Securities

As of December 31, 2023, the latest available investment ratings of all obligations of states and political subdivisions, privately issued mortgage-backed securities and other debt securities were:


					Average Credit Rating of Fair Value Amount
(Dollars in millions)	Amortized Cost		Estimated Fair Value		A or Better		BBB		BB		B or Less		Not Rated
Obligations of states and political subdivisions	$	2,501	$	2,434	$	2,426	$	1	$	—	$	—	$	7
Privately issued mortgage- backed securities		42		46		—		—		—		1		45
Other debt securities		178		167		8		73		31		—		55

Amortized Cost and Estimated Fair Value of Debt Securities by Contractual Maturity

At December 31, 2023, the amortized cost and estimated fair value of debt securities by contractual maturity were as follows:


(Dollars in millions)	Amortized Cost		Estimated Fair Value
Debt securities available for sale:
Due in one year or less	$	5,023	$	4,970
Due after one year through five years		2,921		2,856
Due after five years through ten years		50		44
Due after ten years		—		—
		7,994		7,870
Mortgage-backed securities		2,697		2,570
	$	10,691	$	10,440
Debt securities held to maturity:
Due in one year or less	$	15	$	14
Due after one year through five years		1,179		1,147
Due after five years through ten years		1,351		1,327
Due after ten years		963		922
		3,508		3,410
Mortgage-backed securities		11,822		10,898
	$	15,330	$	14,308

Investment Securities in Continuous Unrealized Loss Position

A summary of investment securities that as of December 31, 2023 and 2022 had been in a continuous unrealized loss position for less than twelve months and those that had been in a continuous unrealized loss position for twelve months or longer follows:


	Less Than 12 Months				12 Months or More
(Dollars in millions)	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
December 31, 2023
Investment securities available for sale:
U.S. Treasury and federal agencies	$	229	$	1	$	7,474	$	112
Mortgage-backed securities:
Government issued or guaranteed:
Commercial		74		1		330		8
Residential		151		2		1,959		116
Other debt securities		6		—		154		11
		460		4		9,917		247
Investment securities held to maturity:
U.S. Treasury and federal agencies		50		—		924		31
Obligations of states and political subdivisions		218		3		2,172		64
Mortgage-backed securities:
Government issued or guaranteed:
Commercial		328		9		1,575		121
Residential		955		11		7,139		791
Privately issued		—		—		34		5
		1,551		23		11,844		1,012
Total	$	2,011	$	27	$	21,761	$	1,259

December 31, 2022
Investment securities available for sale:
U.S. Treasury and federal agencies	$	6,707	$	184	$	842	$	59
Mortgage-backed securities:
Government issued or guaranteed:
Commercial		574		21		—		—
Residential		2,296		169		29		2
Other debt securities		93		4		73		6
		9,670		378		944		67
Investment securities held to maturity:
U.S. Treasury and federal agencies		1,008		46		—		—
Obligations of states and political subdivisions		2,449		117		—		—
Mortgage-backed securities:
Government issued or guaranteed:
Commercial		809		103		—		—
Residential		6,293		619		1,319		272
Privately issued		—		—		36		8
		10,559		885		1,355		280
Total	$	20,229	$	1,263	$	2,299	$	347

Loans and Leases - Loan Modification Activities that were Considered Troubled Debt Restructurings (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2022 USD ($) Modification	Dec. 31, 2021 USD ($) Modification
Financing Receivable, Modifications [Line Items]
Number of modifications \| Modification	3,641	2,320
Pre-modification Recorded Investment	$ 276	$ 534
Loans and leases, net of unearned discount	$ 280	$ 529
Commercial and Industrial [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications \| Modification	231	348
Pre-modification Recorded Investment	$ 98	$ 205
Loans and leases, net of unearned discount	$ 98	$ 202
Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications \| Modification	12	35
Pre-modification Recorded Investment	$ 25	$ 184
Loans and leases, net of unearned discount	$ 25	$ 182
Other Commercial Construction [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications \| Modification	3	1
Residential [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications \| Modification	274	373
Pre-modification Recorded Investment	$ 71	$ 108
Loans and leases, net of unearned discount	$ 75	$ 108
Residential Limited Documentation [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications \| Modification	8	21
Pre-modification Recorded Investment	$ 1	$ 3
Loans and leases, net of unearned discount	$ 1	$ 3
Home Equity Lines and Loans [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications \| Modification	144	89
Pre-modification Recorded Investment	$ 10	$ 6
Loans and leases, net of unearned discount	$ 10	$ 6
Recreational Finance [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications \| Modification	729	281
Pre-modification Recorded Investment	$ 28	$ 10
Loans and leases, net of unearned discount	$ 28	$ 10
Automobile [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications \| Modification	2,092	807
Pre-modification Recorded Investment	$ 42	$ 15
Loans and leases, net of unearned discount	$ 42	$ 15
Other [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications \| Modification	149	362
Pre-modification Recorded Investment	$ 1	$ 3
Loans and leases, net of unearned discount	$ 1	$ 3
Residential Builder and Developer [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications \| Modification	1	1
Principal Deferral [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	$ 203	$ 247
Principal Deferral [Member] \| Commercial and Industrial [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	58	58
Principal Deferral [Member] \| Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	9	57
Principal Deferral [Member] \| Residential [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	55	95
Principal Deferral [Member] \| Residential Limited Documentation [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	1	3
Principal Deferral [Member] \| Home Equity Lines and Loans [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	9	6
Principal Deferral [Member] \| Recreational Finance [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	28	10
Principal Deferral [Member] \| Automobile [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	42	15
Principal Deferral [Member] \| Other [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	1	3
Other [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	3	72
Other [Member] \| Commercial and Industrial [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	3	45
Other [Member] \| Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount		27
Combination of Concession Types [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	74	210
Combination of Concession Types [Member] \| Commercial and Industrial [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	37	99
Combination of Concession Types [Member] \| Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	16	98
Combination of Concession Types [Member] \| Residential [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	20	$ 13
Combination of Concession Types [Member] \| Home Equity Lines and Loans [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	$ 1

Fair value measurements (Tables)

12 Months Ended

Dec. 31, 2023

Fair Value Disclosures [Abstract]

Assets and Liabilities Measured at Estimated Fair Value on Recurring Basis

The following tables present assets and liabilities at December 31, 2023 and 2022 measured at estimated fair value on a recurring basis:


(Dollars in millions)	Fair Value Measurements		Level 1		Level 2		Level 3
December 31, 2023
Trading account	$	106	$	101	$	5	$	—
Investment securities available for sale:
U.S. Treasury and federal agencies		7,705		—		7,705		—
Mortgage-backed securities:
Government issued or guaranteed
Commercial		416		—		416		—
Residential		2,154		—		2,154		—
Other debt securities		165		—		165		—
		10,440		—		10,440		—
Equity securities		268		258		10		—
Real estate loans held for sale		379		—		379		—
Other assets (a)		324		—		309		15
Total assets	$	11,517	$	359	$	11,143	$	15
Other liabilities (a)	$	943	$	—	$	911	$	32
Total liabilities	$	943	$	—	$	911	$	32

December 31, 2022
Trading account	$	118	$	118	$	—	$	—
Investment securities available for sale:
U.S. Treasury and federal agencies		7,671		—		7,671		—
Mortgage-backed securities:
Government issued or guaranteed
Commercial		574		—		574		—
Residential		2,330		—		2,330		—
Other debt securities		174		—		174		—
		10,749		—		10,749		—
Equity securities		151		145		6		—
Real estate loans held for sale		162		—		162		—
Other assets (a)		435		—		435		—
Total assets	$	11,615	$	263	$	11,352	$	—
Other liabilities (a)	$	1,355	$	—	$	1,309	$	46
Total liabilities	$	1,355	$	—	$	1,309	$	46

(a)

Comprised predominantly of interest rate swap agreements used for interest rate risk management (Level 2), interest rate and foreign exchange contracts not designated as hedging instruments (Level 2), commitments to sell real estate loans (Level 2) and commitments to originate real estate loans to be held for sale (Level 3).

Changes in Level 3 Assets and Liabilities Measured at Estimated Fair Value on Recurring Basis

The changes in Level 3 assets and liabilities measured at estimated fair value on a recurring basis during the years ended December 31, 2023, 2022 and 2021 were as follows:


	Other Assets and Other Liabilities
(Dollars in millions)	2023			2022			2021
Beginning balance	$	(46	)	$	6		$	43
Total gains (losses) realized/unrealized:
Included in earnings (a)		36			(34	)		126
Transfers out of Level 3 (b)		(7	)		(18	)		(163	)
Ending balance	$	(17	)	$	(46	)	$	6
Changes in net unrealized gains (losses) included in earnings related to instruments still held at period end (a)	$	15		$	(46	)	$	9

(a)

Reported as "mortgage banking revenues" in the Consolidated Statement of Income and includes the fair value of commitment issuances and expirations.

(b)

Transfers out of Level 3 consist of interest rate locks transferred to closed loans.

Quantitative Information Related to Significant Unobservable Inputs

The following tables present quantitative information about significant unobservable inputs used in the fair value measurements for Level 3 assets and liabilities at December 31, 2023 and 2022:


(Dollars in millions)	Fair Value			Valuation Technique	Unobservable Inputs / Assumptions	Range (Weighted- Average)
December 31, 2023
Recurring fair value measurements
Net other assets (liabilities) (a)	$	(17	)	Discounted cash flow	Commitment expirations	0% - 99% (5%)

December 31, 2022
Recurring fair value measurements
Net other assets (liabilities) (a)	$	(46	)	Discounted cash flow	Commitment expirations	0% - 97% (3%)

(a)

Other Level 3 assets (liabilities) consist of commitments to originate real estate loans.

Carrying Amounts and Estimated Fair Value for Financial Instrument Assets (Liabilities)

The carrying amounts and estimated fair value for financial instrument assets (liabilities) are presented in the following tables:


	December 31, 2023
(Dollars in millions)	Carrying Amount			Estimated Fair Value			Level 1		Level 2			Level 3
Financial assets:
Cash and cash equivalents	$	1,731		$	1,731		$	1,668	$	63		$	—
Interest-bearing deposits at banks		28,069			28,069			—		28,069			—
Trading account		106			106			101		5			—
Investment securities		26,897			25,875			258		25,571			46
Loans and leases, net		131,939			129,138			—		7,240			121,898
Accrued interest receivable		786			786			—		786			—
Financial liabilities:
Noninterest-bearing deposits	$	(49,294	)	$	(49,294	)	$	—	$	(49,294	)	$	—
Savings and interest-checking deposits		(93,221	)		(93,221	)		—		(93,221	)		—
Time deposits		(20,759	)		(20,715	)		—		(20,715	)		—
Short-term borrowings		(5,316	)		(5,316	)		—		(5,316	)		—
Long-term borrowings		(8,201	)		(8,107	)		—		(8,107	)		—
Accrued interest payable		(482	)		(482	)		—		(482	)		—
Other financial instruments:
Commitments to originate real estate loans for sale	$	(17	)	$	(17	)	$	—	$	—		$	(17	)
Commitments to sell real estate loans		30			30			—		30			—
Other credit-related commitments		(154	)		(154	)		—		—			(154	)
Interest rate swap agreements used for interest rate risk management		10			10			—		10			—
Interest rate and foreign exchange contracts not designated as hedging instruments		(642	)		(642	)		—		(642	)		—


	December 31, 2022
(Dollars in millions)	Carrying Amount			Estimated Fair Value			Level 1		Level 2			Level 3
Financial assets:
Cash and cash equivalents	$	1,517		$	1,517		$	1,372	$	145		$	—
Interest-bearing deposits at banks		24,959			24,959			—		24,959			—
Federal funds sold		3			3			—		3			—
Trading account		118			118			118		—			—
Investment securities		25,211			24,056			145		23,860			51
Loans and leases, net		129,639			126,228			—		7,180			119,048
Accrued interest receivable		646			646			—		646			—
Financial liabilities:
Noninterest-bearing deposits	$	(65,502	)	$	(65,502	)	$	—	$	(65,502	)	$	—
Savings and interest-checking deposits		(87,911	)		(87,911	)		—		(87,911	)		—
Time deposits		(10,102	)		(10,143	)		—		(10,143	)		—
Short-term borrowings		(3,555	)		(3,555	)		—		(3,555	)		—
Long-term borrowings		(3,965	)		(3,926	)		—		(3,926	)		—
Accrued interest payable		(81	)		(81	)		—		(81	)		—
Other financial instruments:
Commitments to originate real estate loans for sale	$	(46	)	$	(46	)	$	—	$	—		$	(46	)
Commitments to sell real estate loans		54			54			—		54			—
Other credit-related commitments		(149	)		(149	)		—		—			(149	)
Interest rate swap agreements used for interest rate risk management		(8	)		(8	)		—		(8	)		—
Interest rate and foreign exchange contracts not designated as hedging instruments		(920	)		(920	)		—		(920	)		—

Parent company financial statements

12 Months Ended

Dec. 31, 2023

Condensed Financial Information Disclosure [Abstract]

Parent company financial statements

26. Parent company financial statements

Condensed Balance Sheet


	December 31,
(Dollars in millions)	2023		2022
Assets
Cash in subsidiary bank	$	176	$	130
Due from consolidated bank subsidiaries:
Money-market savings		3,223		1,690
Current income tax receivable		5		4
Total due from consolidated bank subsidiaries		3,228		1,694
Investments in consolidated subsidiaries:
Banks		26,290		25,005
Other		391		380
Investments in trust preferred entities (note 20)		22		22
Other assets		100		93
Total assets	$	30,207	$	27,324
Liabilities
Accrued expenses and other liabilities	$	152	$	172
Long-term borrowings		3,098		1,834
Total liabilities		3,250		2,006
Shareholders’ equity		26,957		25,318
Total liabilities and shareholders’ equity	$	30,207	$	27,324

Condensed Statement of Income


	Year Ended December 31,
(Dollars in millions, except per share)	2023			2022			2021
Income
Dividends from consolidated subsidiaries	$	2,041		$	2,508		$	1,025
Income from Bayview Lending Group LLC		20			30			30
Other income		6			(7	)		3
Total income		2,067			2,531			1,058
Expense
Interest on short-term borrowings		—			6			—
Interest on long-term borrowings		182			57			24
Other expense		40			50			36
Total expense		222			113			60
Income before income taxes and equity in undistributed income of subsidiaries		1,845			2,418			998
Income tax credits		49			22			6
Income before equity in undistributed income of subsidiaries		1,894			2,440			1,004
Equity in undistributed income of subsidiaries
Net income of subsidiaries		2,888			2,060			1,880
Less: dividends received		(2,041	)		(2,508	)		(1,025	)
Equity in undistributed income of subsidiaries		847			(448	)		855
Net income	$	2,741		$	1,992		$	1,859
Net income per common share
Basic	$	15.85		$	11.59		$	13.81
Diluted		15.79			11.53			13.80

Condensed Statement of Cash Flows


	Year Ended December 31,
(Dollars in millions)	2023			2022			2021
Cash flows from operating activities
Net income	$	2,741		$	1,992		$	1,859
Adjustments to reconcile net income to net cash provided by operating activities:
Equity in undistributed income of subsidiaries		(847	)		448			(855	)
Provision for deferred income taxes		(5	)		7			10
Net change in accrued income and expense		32			8			(23	)
Net cash provided by operating activities		1,921			2,455			991
Cash flows from investing activities
Net investment in consolidated subsidiaries		(1	)		54			(199	)
Acquisition, net of cash consideration		—			538			—
Other, net		(41	)		24			(3	)
Net cash provided (used) by investing activities		(42	)		616			(202	)
Cash flows from financing activities
Repayment of short-term borrowings assumed in acquisition		—			(500	)		—
Proceeds from long-term borrowings		1,998			499			—
Payments on long-term borrowings		(750	)		—			—
Purchases of treasury stock		(594	)		(1,800	)		—
Dividends paid — common		(868	)		(784	)		(580	)
Dividends paid — preferred		(100	)		(97	)		(68	)
Proceeds from issuance of Series I preferred stock		—			—			495
Other, net		14			2			(7	)
Net cash used by financing activities		(300	)		(2,680	)		(160	)
Net increase in cash and cash equivalents		1,579			391			629
Cash and cash equivalents at beginning of year		1,820			1,429			800
Cash and cash equivalents at end of year	$	3,399		$	1,820		$	1,429
Supplemental disclosure of cash flow information
Interest received during the year	$	6		$	1		$	1
Interest paid during the year		135			49			20
Income taxes received during the year		43			28			53

Stock-based compensation plans (Tables)

12 Months Ended

Dec. 31, 2023

Share-Based Payment Arrangement [Abstract]

Summary of Restricted Stock and Restricted Stock Unit Activity

A summary of restricted stock and restricted stock unit activity follows:


	Restricted Stock Units Outstanding			Weighted- Average Grant Price		Restricted Stock Outstanding			Weighted- Average Grant Price
Unvested at January 1, 2023		1,167,582		$	156.23		75,006		$	164.65
Granted		752,534			153.86		—			—
Vested		(543,987	)		156.97		(35,777	)		164.66
Cancelled		(45,851	)		159.73		(7,514	)		164.66
Unvested at December 31, 2023		1,330,278		$	154.46		31,715		$	164.63

Summary of Stock Option Activity

A summary of stock option activity follows:


				Weighted-Average
	Stock Options Outstanding			Exercise Price		Life (In Years)		Aggregate Intrinsic Value (In millions)
Outstanding at January 1, 2023		2,340,062		$	148.78
Granted		179,551			156.00
Exercised		(262,837	)		122.45
Expired		(58,112	)		155.87
Outstanding at December 31, 2023		2,198,664		$	152.33		5.6	$	6
Exercisable at December 31, 2023		1,807,515		$	151.67		5.0	$	5

Regulatory Matters - Additional Information (Detail) $ in Billions	Dec. 31, 2023 USD ($)	Oct. 01, 2023
Broker-Dealer, Net Capital Requirement, SEC Regulation [Abstract]
Funds available for payment of dividends to M&T from banking subsidiaries	$ 1.7
Capital conservation buffer	2.50%
Capital conservation buffer ratio effective		4
CET1 capital requirement ratio	8.50%

Consolidated Statement of Changes in Shareholders' Equity - USD ($) $ in Millions	Total	Series I Preferred Stock [Member]	Series H Preferred Stock [Member]	Preferred Stock [Member]	Preferred Stock [Member] Series I Preferred Stock [Member]	Preferred Stock [Member] Series H Preferred Stock [Member]	Common Stock [Member]	Common Stock Issuable [Member]	Additional Paid-in Capital [Member]	Additional Paid-in Capital [Member] Series I Preferred Stock [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss), Net [Member]	Treasury Stock [Member]
Beginning balance at Dec. 31, 2020	$ 16,187			$ 1,250			$ 80	$ 1	$ 6,617		$ 13,444	$ (62)	$ (5,143)
Total comprehensive income	1,794										1,859	(65)
Preferred stock cash dividends	(73)										(73)
Issuance of preferred stock		$ 495			$ 500					$ (5)
Stock-based compensation transactions, net	83								23		(1)		61
Common stock cash dividends	(583)										(583)
Ending balance at Dec. 31, 2021	17,903			1,750			80	1	6,635		14,646	(127)	(5,082)
Total comprehensive income	1,329										1,992	(663)
Common stock issued	8,286						10		3,256				5,020
Common stock awards converted	105								105
Preferred stock cash dividends	(97)										(97)
Issuance of preferred stock			$ 261			$ 261
Purchases of treasury stock	(1,800)												(1,800)
Stock-based compensation transactions, net	117								6		(1)		112
Common stock cash dividends	(786)										(786)
Ending balance at Dec. 31, 2022	25,318			2,011			90	1	10,002		15,754	(790)	(1,750)
Total comprehensive income	3,072										2,741	331
Preferred stock cash dividends	(100)										(100)
Purchases of treasury stock	(600)												(600)
Stock-based compensation transactions, net	136								18		(2)		120
Common stock cash dividends	(869)										(869)
Ending balance at Dec. 31, 2023	$ 26,957			$ 2,011			$ 90	$ 1	$ 10,020		$ 17,524	$ (459)	$ (2,230)

- Definition

Equity impact of the value of new stock issued during the period. Includes shares issued in an initial public offering or a secondary public offering.

+ References + Details

- Definition

Amount of equity (deficit) attributable to parent. Excludes temporary equity and equity attributable to noncontrolling interest.

+ References

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+ Details

Borrowings (Tables)

12 Months Ended

Dec. 31, 2023

Debt Disclosure [Abstract]

Amounts and Interest Rates of Short-term Borrowings

The amounts and interest rates of short-term borrowings were as follows:


(Dollars in millions)	Repurchase Agreements			FHLB Advances			Total
At December 31, 2023
Amount outstanding	$	316		$	5,000		$	5,316
Weighted-average interest rate		3.26	%		5.35	%		5.23	%
At December 31, 2022
Amount outstanding	$	355		$	3,200		$	3,555
Weighted-average interest rate		1.01	%		4.59	%		4.24	%

Long-term Borrowings

Long-term borrowings were as follows:


	December 31,
(Dollars in millions)	2023		2022
Senior notes of M&T:
Variable rate due 2023	$	—	$	250
3.55% due 2023		—		494
4.55% fixed/variable due 2028		484		477
7.41% fixed/variable due 2029		1,028		—
5.05% fixed/variable due 2034		970		—
Senior notes of M&T Bank:
2.90% due 2025		750		750
5.40% due 2025		499		499
4.65% due 2026		1,296		—
4.70% due 2028		1,196		—
Subordinated notes of M&T:
5.75% due 2024		76		77
Subordinated notes of M&T Bank:
4.00% due 2024		401		404
3.40% due 2027		472		463
Junior subordinated debentures of M&T associated with preferred capital securities:
Fixed rates:
BSB Capital Trust I — 8.125%, due 2028		16		16
Provident Trust I — 8.29%, due 2028		32		31
Southern Financial Statutory Trust I — 10.60%, due 2030		7		7
Variable rates:
First Maryland Capital I — due 2027		150		150
First Maryland Capital II — due 2027		153		152
Allfirst Asset Trust — due 2029		98		97
BSB Capital Trust III — due 2033		15		15
Provident Statutory Trust III — due 2033		60		59
Southern Financial Capital Trust III — due 2033		9		9
Asset-backed notes		474		—
Other		15		15
	$	8,201	$	3,965

Maturity of Long-term Borrowings

Long-term borrowings at December 31, 2023 mature as follows:


(Dollars in millions)
Year ending December 31:
2024	$	527
2025		1,251
2026		1,297
2027		775
2028		1,728
Later years		2,623
	$	8,201

- Definition

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

+ References

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+ Details

Comprehensive income

12 Months Ended

Dec. 31, 2023

Equity [Abstract]

Comprehensive income

16. Comprehensive income

The following tables display the components of other comprehensive income (loss) and amounts reclassified from accumulated other comprehensive income (loss) to net income:


	Investment			Defined Benefit			Cash Flow Hedges and			Total Amount				Income
(Dollars in millions)	Securities			Plans			Other			Before Tax				Tax			Net
Balance — January 1, 2023	$	(444	)	$	(273	)	$	(349	)	$	(1,066	)		$	276		$	(790	)
Other comprehensive income before reclassifications:
Unrealized holding gains, net		193			—			—			193				(51	)		142
Foreign currency translation adjustment		—			—			5			5				(1	)		4
Unrealized losses on cash flow hedges		—			—			(116	)		(116	)			30			(86	)
Current year benefit plans gains		—			125			—			125				(33	)		92
Total other comprehensive income (loss) before reclassifications		193			125			(111	)		207				(55	)		152
Amounts reclassified from accumulated other comprehensive income that (increase) decrease net income:
Net yield adjustment from cash flow hedges currently in effect		—			—			250			250		(a)		(66	)		184
Amortization of prior service credit		—			(2	)		—			(2	)	(b)		1			(1	)
Amortization of actuarial gains		—			(5	)		—			(5	)	(b)		1			(4	)
Total other comprehensive income (loss)		193			118			139			450				(119	)		331
Balance — December 31, 2023	$	(251	)	$	(155	)	$	(210	)	$	(616	)		$	157		$	(459	)

Balance — January 1, 2022	$	105		$	(360	)	$	84		$	(171	)		$	44		$	(127	)
Other comprehensive income before reclassifications:
Unrealized holding losses, net		(551	)		—			—			(551	)			143			(408	)
Foreign currency translation adjustment		—			—			(8	)		(8	)			2			(6	)
Unrealized losses on cash flow hedges		—			—			(461	)		(461	)			119			(342	)
Current year benefit plans gains		—			71			—			71				(18	)		53
Total other comprehensive income (loss) before reclassifications		(551	)		71			(469	)		(949	)			246			(703	)
Amounts reclassified from accumulated other comprehensive income that (increase) decrease net income:
Amortization of unrealized holding losses on held-to-maturity securities		2			—			—			2		(a)		(1	)		1
Net yield adjustment from cash flow hedges currently in effect		—			—			36			36		(a)		(9	)		27
Amortization of prior service credit		—			(2	)		—			(2	)	(b)		—			(2	)
Amortization of actuarial losses		—			18			—			18		(b)		(4	)		14
Total other comprehensive income (loss)		(549	)		87			(433	)		(895	)			232			(663	)
Balance — December 31, 2022	$	(444	)	$	(273	)	$	(349	)	$	(1,066	)		$	276		$	(790	)


	Investment			Defined Benefit			Cash Flow Hedges and			Total Amount				Income
(Dollars in millions)	Securities			Plans			Other			Before Tax				Tax			Net
Balance — January 1, 2021	$	196		$	(650	)	$	370		$	(84	)		$	22		$	(62	)
Other comprehensive income before reclassifications:
Unrealized holding losses, net		(95	)		—			—			(95	)			25			(70	)
Foreign currency translation adjustment		—			—			(1	)		(1	)			—			(1	)
Unrealized losses on cash flow hedges		—			—			(32	)		(32	)			8			(24	)
Current year benefit plans gains		—			206			—			206				(54	)		152
Total other comprehensive income (loss) before reclassifications		(95	)		206			(33	)		78				(21	)		57
Amounts reclassified from accumulated other comprehensive income that (increase) decrease net income:
Amortization of unrealized holding losses on held-to-maturity securities		4			—			—			4		(a)		(1	)		3
Net yield adjustment from cash flow hedges currently in effect		—			—			(253	)		(253	)	(a)		66			(187	)
Amortization of prior service credit		—			(4	)		—			(4	)	(b)		1			(3	)
Amortization of actuarial losses		—			88			—			88		(b)		(23	)		65
Total other comprehensive income (loss)		(91	)		290			(286	)		(87	)			22			(65	)
Balance — December 31, 2021	$	105		$	(360	)	$	84		$	(171	)		$	44		$	(127	)

(a)

Included in interest income.

(b)

Included in other costs of operations.

Accumulated other comprehensive income (loss), net consisted of the following:


(Dollars in millions)	Investment Securities			Defined Benefit Plans			Cash Flow Hedges and Other			Total
Balance at January 1, 2021	$	145		$	(481	)	$	274		$	(62	)
Net gain (loss) during 2021		(67	)		214			(212	)		(65	)
Balance at December 31, 2021		78			(267	)		62			(127	)
Net gain (loss) during 2022		(407	)		65			(321	)		(663	)
Balance at December 31, 2022		(329	)		(202	)		(259	)		(790	)
Net gain during 2023		142			87			102			331
Balance at December 31, 2023	$	(187	)	$	(115	)	$	(157	)	$	(459	)

Earnings Per Common Share - Computations of Diluted Earnings Per Common Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Earnings Per Share [Abstract]
Net income available to common equity	$ 2,641	$ 1,895	$ 1,786
Less: Income attributable to unvested stock-based compensation awards	(5)	(4)	(9)
Net income available to common shareholders	$ 2,636	$ 1,891	$ 1,777
Adjusted weighted-average shares outstanding:
Common shares outstanding (including common stock issuable) and unvested stock-based compensation awards	166,662	163,489	129,539
Less: Unvested stock-based compensation awards	(301)	(315)	(890)
Plus: Incremental shares from assumed conversion of stock-based compensation awards and warrants to purchase common stock	641	856	163
Adjusted weighted-average shares outstanding	167,002	164,030	128,812
Diluted earnings per common share	$ 15.79	$ 11.53	$ 13.8

Consolidated Statement of Changes in Shareholders' Equity (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Retained Earnings [Member]
Common stock per share dividend amount	$ 5.20	$ 4.80	$ 4.50

Consolidated Statement of Income - USD ($) $ in Millions	12 Months Ended
Consolidated Statement of Income - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Interest income
Loans and leases, including fees	$ 8,021	$ 5,237	$ 3,749
Investment securities
Fully taxable	773	448	141
Exempt from federal taxes	66	51
Deposits at banks	1,360	509	48
Other	4	2	1
Total interest income	10,224	6,247	3,939
Interest expense
Savings and interest-checking deposits	1,746	271	33
Time deposits	671	24	19
Short-term borrowings	292	19
Long-term borrowings	400	111	62
Total interest expense	3,109	425	114
Net interest income	7,115	5,822	3,825
Provision for credit losses	645	517	(75)
Net interest income after provision for credit losses	6,470	5,305	3,900
Other income
Brokerage services income	102	88	63
Trading account and other non-hedging derivative gains	49	27	24
Gain (loss) on bank investment securities	4	(6)	(21)
Other revenues from operations	809	703	483
Total other income	2,528	2,357	2,167
Other expense
Salaries and employee benefits	2,997	2,787	2,046
Equipment and net occupancy	520	474	327
Outside data processing and software	437	376	292
Professional and other services	413	509	379
FDIC assessments	315	90	70
Advertising and marketing	108	90	64
Amortization of core deposit and other intangible assets	62	56	10
Other costs of operations	527	668	424
Total other expense	5,379	5,050	3,612
Income before taxes	3,619	2,612	2,455
Income taxes	878	620	596
Net income	2,741	1,992	1,859
Net income available to common shareholders
Basic	2,636	1,891	1,777
Diluted	$ 2,636	$ 1,891	$ 1,777
Net income per common share
Basic	$ 15.85	$ 11.59	$ 13.81
Diluted	$ 15.79	$ 11.53	$ 13.8
Mortgage Banking Revenues [Member]
Other income
Revenue from contract with customer	$ 409	$ 357	$ 571
Service Charges on Deposit Accounts [Member]
Other income
Revenue from contract with customer	475	447	402
Trust Income [Member]
Other income
Revenue from contract with customer	$ 680	$ 741	$ 645

Loans and Leases - Summary of Payment Status of Loans Modified (Parenthetical) (Details) $ in Millions	Dec. 31, 2023 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
30-89 Days Past Due	$ 123
Past Due 90 Days or More	49
Guaranteed by Government-Related Entities [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
30-89 Days Past Due	40
Past Due 90 Days or More	$ 24

International Activities - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
International Activities [Line Items]
Revenues from international trust-related services	$ 42	$ 36	$ 38
Loans and leases	131,939	129,639
Canada [Member]
International Activities [Line Items]
Deposits at foreign office	28	34
Geographic Distribution, Foreign [Member]
International Activities [Line Items]
Loans and leases	$ 303	$ 319
Geographic Concentration Risk [Member] \| Sales Revenue, Net [Member] \| Maximum [Member]
International Activities [Line Items]
Concentration risk percentage	1.00%

Shareholders' Equity - Issued and Outstanding Preferred Stock (Parenthetical) (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Class Of Stock [Line Items]
Preferred stock, liquidation preference per share	$ 25	$ 25
Series E Fixed-To-Floating Rate Non-Cumulative Perpetual Preferred Stock [Member]
Class Of Stock [Line Items]
Preferred stock, liquidation preference per share	$ 1,000	$ 1,000
Preferred stock dividend rate	6.45%	6.45%
Date of change in the dividend rate	Feb. 14, 2024	Feb. 14, 2024
Secured overnight financing rate plus basis points	3.87%	3.87%
Preferred shares redemption date	Feb. 15, 2024	Feb. 15, 2024
Preferred Stock, Redemption Feature, Redemption Term	90 days	90 days
Preferred stock, dividend declared per share	$ 64.5	$ 64.5	$ 64.5
Series F Fixed-to-Floating Rate Non-Cumulative Perpetual Preferred Stock [Member]
Class Of Stock [Line Items]
Preferred stock, liquidation preference per share	$ 10,000	$ 10,000
Preferred stock dividend rate	5.125%	5.125%
Date of change in the dividend rate	Oct. 31, 2026	Oct. 31, 2026
Secured overnight financing rate plus basis points	3.78%	3.78%
Preferred shares redemption date	Nov. 01, 2026	Nov. 01, 2026
Preferred Stock, Redemption Feature, Redemption Term	90 days	90 days
Preferred stock, dividend declared per share	$ 512.5	$ 512.5	512.5
Series G Fixed-Rate Reset Non-Cumulative Perpetual Preferred Stock [Member]
Class Of Stock [Line Items]
Preferred stock, liquidation preference per share	$ 10,000	$ 10,000
Preferred stock dividend rate	5.00%	5.00%
Date of change in the dividend rate	Jul. 31, 2024	Jul. 31, 2024
Preferred shares redemption date	Aug. 01, 2024	Aug. 01, 2024
Preferred Stock, Redemption Feature, Redemption Term	90 days	90 days
Preferred stock, dividend declared per share	$ 500	$ 500	500
U S treasury rate plus additional rate	3.174%	3.174%
Dividend payment terms	five-year	five-year
Series H Fixed-to-Floating Rate Non-cumulative Perpetual Preferred Stock [Member]
Class Of Stock [Line Items]
Preferred stock, liquidation preference per share	$ 25	$ 25
Preferred stock dividend rate	5.625%	5.625%
Date of change in the dividend rate	Dec. 14, 2026	Dec. 14, 2026
Secured overnight financing rate plus basis points	4.28%	4.28%
Preferred shares redemption date	Apr. 01, 2027	Apr. 01, 2027
Preferred Stock, Redemption Feature, Redemption Term	90 days	90 days
Preferred stock, dividend declared per share	$ 1.4063	$ 1.0547
Series I Fixed-Rate Reset Non-Cumulative Perpetual Preferred Stock [Member]
Class Of Stock [Line Items]
Preferred stock, liquidation preference per share	$ 10,000	$ 10,000
Preferred stock dividend rate	3.50%	3.50%
Date of change in the dividend rate	Aug. 31, 2026	Aug. 31, 2026
Preferred shares redemption date	Sep. 01, 2026	Sep. 01, 2026
Preferred Stock, Redemption Feature, Redemption Term	90 days	90 days
Preferred stock, dividend declared per share	$ 350	$ 356.806	$ 94.306
U S treasury rate plus additional rate	2.679%	2.679%
Dividend payment terms	five-year	five-year

International activities

12 Months Ended

Dec. 31, 2023

International Activities [Abstract]

International Activities

18. International activities

The Company engages in limited international activities including certain trust-related services in Europe, foreign currency transactions associated with customer activity, providing credit to support the international activities of domestic companies, holding certain loans to foreign borrowers and, prior to June 2021, collecting Eurodollar deposits for a Cayman Islands office. Assets and revenues associated with international activities represent less than 1% of the Company’s consolidated assets

and revenues. International assets included $303 million and $319 million of loans to foreign borrowers at December 31, 2023 and 2022, respectively. Deposits at M&T Bank’s office in Ontario, Canada were $28 million at December 31, 2023 and $34 million at December 31, 2022. Revenues from providing international trust-related services were approximately $42 million in 2023, $36 million in 2022 and $38 million in 2021.

Pay vs Performance Disclosure - USD ($) $ in Millions	12 Months Ended
Pay vs Performance Disclosure - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Pay vs Performance Disclosure
Net Income (Loss)	$ 2,741	$ 1,992	$ 1,859

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
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-Name Accounting Standards Codification
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-URI https://asc.fasb.org//1943274/2147482740/230-10-45-28

Reference 36: http://www.xbrl.org/2003/role/disclosureRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 1A
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482790/220-10-45-1A

Reference 37: http://www.xbrl.org/2003/role/disclosureRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 1B
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482790/220-10-45-1B

Reference 38: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(20))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483621/220-10-S99-2

Reference 39: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 942
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(22))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483589/942-220-S99-1

+ Details

Fair Value Measurements - Quantitative Information Related to Significant Unobservable Inputs (Detail) - Fair Value Measurements, Recurring [Member] - Other Assets and Other Liabilities [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Minimum [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Commitment expirations	0.00%	0.00%
Maximum [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Commitment expirations	99.00%	97.00%
Weighted Average [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Commitment expirations	(5.00%)	(3.00%)
Discounted Cash Flows [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Recurring fair value measurements for certain Level 3 Assets and Liabilities	$ (17)	$ (46)

Acquisition and Divestitures - Summary of Identifiable Assets Acquired, Liabilities Assumed and Preferred Stock Exchanged as of Acquisition (Details) - USD ($) $ in Millions	Apr. 01, 2022	Dec. 31, 2023	Dec. 31, 2022
Liabilities and preferred stock:
Total liabilities and shareholders’ equity		$ 208,264	$ 200,730
Goodwill		$ 8,465	$ 8,490
Peoples United Financial Inc [Member]
Consideration:
Common stock issued (50,325,004 shares)	$ 8,286
Common stock awards converted	105
Cash	2
Total consideration	8,393
Identifiable assets
Cash and due from banks	396
Interest-bearing deposits at banks	9,193
Investment securities	11,575
Loans and leases	35,841
Core deposit and other intangible assets	261
Other assets	2,979
Total identifiable assets acquired	60,245
Liabilities and preferred stock:
Deposits	52,968
Borrowings	1,389
Other liabilities	1,142
Total liabilities assumed	55,499
Preferred stock	261
Total liabilities and shareholders’ equity	55,760
Net assets acquired	4,485
Goodwill	$ 3,908

Variable Interest Entities and Asset Securitizations - Additional Information (Detail) - USD ($)	1 Months Ended	12 Months Ended
	Aug. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Loss on securitization of assets		$ 0
Loans and leases		131,939,000,000	$ 129,639,000,000
Asset-backed notes		474,000,000
Remaining balance of loans and leases		134,936,000,000	132,074,000,000
Other assets for its "investment" in the common securities recognized by the company of various trusts		22,000,000	22,000,000
Total assets of partnerships in which the company invested		208,264,000,000	200,730,000,000
Investment in partnership carrying amount		1,500,000,000	1,500,000,000
Unfunded commitments includes carrrying amount of its investments		441,000,000	545,000,000
Contingent Commitments to Provide Additional Capital Contributions to Partnerships		55,000,000
Maximum exposure to loss of investments in real estate partnerships		2,100,000,000
Asset-Backed Notes [Member]
Loans and leases	$ 666,000,000
Senior notes	$ 550,000,000
Asset-backed notes weighed average estimated life	2 years
Loans and leases average rate	5.84%
Asset-backed notes	$ 88,000,000	474,000,000
Remaining balance of loans and leases		599,000,000
Variable Interest Entity Primary Beneficiary [Member]
Total assets of partnerships in which the company invested		$ 9,800,000,000	$ 9,200,000,000

Comprehensive Income - Components of Other Comprehensive Income (Loss) and Amounts Reclassified from Accumulated Other Comprehensive Income (Loss) to Net Income (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, before tax	$ (1,066)	$ (171)	$ (84)
Unrealized holding gains (losses), net, before tax	193	(551)	(95)
Foreign currency translation adjustment, before tax	5	(8)	(1)
Unrealized losses on cash flow hedges	(116)	(461)	(32)
Current year benefit plans gains, before tax	125	71	206
Total other comprehensive income (loss) before reclassifications, before tax	207	(949)	78
Amortization of unrealized holding losses on held-to-maturity securities		2	4
Net yield adjustment from cash flow hedges currently in effect, before tax	250	36	(253)
Amortization of prior service credit, before tax	(2)	(2)	(4)
Amortization of actuarial gains (losses), before tax	(5)	18	88
Total other comprehensive income (loss), before tax	450	(895)	(87)
Ending balance, before tax	(616)	(1,066)	(171)
Beginning balance, tax	276	44	22
Unrealized holding gains (losses), net, tax	(51)	143	25
Foreign currency translation adjustment, tax	(1)	2
Unrealized losses on cash flow hedges, tax	30	119	8
Current year benefit plans gains, tax	(33)	(18)	(54)
Total other comprehensive income (loss) before reclassifications, tax	(55)	246	(21)
Amortization of unrealized holding losses on held-to-maturity securities, tax		(1)	(1)
Net yield adjustment from cash flow hedges currently in effect, tax	(66)	(9)	66
Amortization of prior service credit, tax	1		1
Amortization of actuarial gains (losses), tax	1	(4)	(23)
Total other comprehensive income (loss), tax	(119)	232	22
Ending balance, tax	157	276	44
Beginning balance, net of tax	(790)	(127)	(62)
Unrealized holding gains (losses), net of tax	142	(408)	(70)
Foreign currency translation adjustments, net of tax	4	(6)	(1)
Unrealized losses on cash flow hedges, net of tax	(86)	(342)	(24)
Current year benefit plans gains, net of tax	92	53	152
Total other comprehensive income (loss) before reclassifications, net of tax	152	(703)	57
Amortization of unrealized holding losses on held-to-maturity securities		1	3
Net yield adjustment from cash flow hedges currently in effect, net of tax	184	27	(187)
Amortization of prior service credit, net of tax	(1)	(2)	(3)
Amortization of actuarial gains (losses), net of tax	(4)	14	65
Total other comprehensive income (loss)	331	(663)	(65)
Ending balance, net of tax	(459)	(790)	(127)
Investment Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, before tax	(444)	105	196
Unrealized holding gains (losses), net, before tax	193	(551)	(95)
Total other comprehensive income (loss) before reclassifications, before tax	193	(551)	(95)
Amortization of unrealized holding losses on held-to-maturity securities		2	4
Total other comprehensive income (loss), before tax	193	(549)	(91)
Ending balance, before tax	(251)	(444)	105
Total other comprehensive income (loss)	142	(407)	(67)
Defined Benefit Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, before tax	(273)	(360)	(650)
Current year benefit plans gains, before tax	125	71	206
Total other comprehensive income (loss) before reclassifications, before tax	125	71	206
Amortization of prior service credit, before tax	(2)	(2)	(4)
Amortization of actuarial gains (losses), before tax	(5)	18	88
Total other comprehensive income (loss), before tax	118	87	290
Ending balance, before tax	(155)	(273)	(360)
Total other comprehensive income (loss)	87	65	214
Cash Flow Hedges and Other [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, before tax	(349)	84	370
Foreign currency translation adjustment, before tax	5	(8)	(1)
Unrealized losses on cash flow hedges	(116)	(461)	(32)
Total other comprehensive income (loss) before reclassifications, before tax	(111)	(469)	(33)
Net yield adjustment from cash flow hedges currently in effect, before tax	250	36	(253)
Total other comprehensive income (loss), before tax	139	(433)	(286)
Ending balance, before tax	$ (210)	$ (349)	$ 84

Allowance for credit losses

12 Months Ended

Dec. 31, 2023

Receivables [Abstract]

Allowance for credit losses

5. Allowance for credit losses

For purposes of determining the level of the allowance for credit losses, the Company evaluates its loan and lease portfolios by type. Changes in the allowance for credit losses for the years ended December 31, 2023, 2022 and 2021 were as follows:


	Commercial			Real Estate
(Dollars in millions)	and industrial			Commercial			Residential			Consumer			Total
2023
Beginning balance	$	568		$	611		$	115		$	631		$	1,925
Provision for credit losses		132			394			4			115			645
Net charge-offs:
Charge-offs		(132	)		(253	)		(10	)		(175	)		(570	)
Recoveries		52			12			7			58			129
Net charge-offs		(80	)		(241	)		(3	)		(117	)		(441	)
Ending balance	$	620		$	764		$	116		$	629		$	2,129

2022
Beginning balance	$	335		$	506		$	72		$	556		$	1,469
Allowance on acquired PCD loans		48			49			2			—			99
Provision for credit losses (a)		244			93			43			137			517
Net charge-offs:
Charge-offs (b)		(119	)		(60	)		(12	)		(112	)		(303	)
Recoveries		60			23			10			50			143
Net charge-offs		(59	)		(37	)		(2	)		(62	)		(160	)
Ending balance	$	568		$	611		$	115		$	631		$	1,925

2021
Beginning balance	$	469		$	607		$	104		$	556		$	1,736
Provision for credit losses		(58	)		(25	)		(30	)		38			(75	)
Net charge-offs:
Charge-offs		(124	)		(100	)		(11	)		(103	)		(338	)
Recoveries		48			24			9			65			146
Net charge-offs		(76	)		(76	)		(2	)		(38	)		(192	)
Ending balance	$	335		$	506		$	72		$	556		$	1,469

________________________________________________

(a)

Includes $242 million related to non-PCD acquired loans recorded on April 1, 2022.

(b)

For the year ended December 31, 2022, net charge-offs do not reflect $33 million of charge-offs related to PCD loans acquired on April 1, 2022.

Despite the allocation in the preceding tables, the allowance for credit losses is general in nature and is available to absorb losses from any loan or lease type. In determining the allowance for credit losses, accruing loans with similar risk characteristics are generally evaluated collectively. The Company utilizes statistically developed models to project principal balances over the remaining contractual lives of the loan portfolios and to determine estimated credit losses through a reasonable and supportable forecast period. Individual loan credit quality indicators, including loan grade and borrower repayment performance, can inform the models, which have been statistically developed based on historical correlations of credit losses with prevailing economic metrics, including unemployment, GDP and real estate prices. Model forecasts may be adjusted for inherent limitations or biases that have been identified through independent validation and back-testing of model performance to actual realized results. At each of December 31, 2023, 2022 and 2021, the Company utilized a reasonable and supportable forecast period of two years. Subsequent to this forecast period the Company reverted, ratably over a one-year period, to historical loss experience to inform its estimate of losses for the remaining contractual life of each portfolio. The Company also considered the impact of portfolio concentrations, changes in underwriting practices, product expansions into new markets, imprecision in its economic forecasts, geopolitical conditions and other risk factors that might influence its loss estimation process.

The Company also estimates losses attributable to specific troubled credits identified through both normal and targeted credit review processes. The amounts of specific loss components in the

Company’s loan and lease portfolios are determined through a loan-by-loan analysis of larger balance commercial and industrial loans and commercial real estate loans that are in nonaccrual status. Such loss estimates are typically based on expected future cash flows, collateral values and other factors that may impact the borrower’s ability to pay. To the extent that those loans are collateral-dependent, they are evaluated based on the fair value of the loan’s collateral as estimated at or near the financial statement date. As the quality of a loan deteriorates to the point of classifying the loan as “criticized,” the process of obtaining updated collateral valuation information is usually initiated, unless it is not considered warranted given factors such as the relative size of the loan, the characteristics of the collateral or the age of the last valuation. In those cases where current appraisals may not yet be available, prior appraisals are utilized with adjustments, as deemed necessary, for estimates of subsequent declines in values as determined by line of business and/or loan workout personnel. Those adjustments are reviewed and assessed for reasonableness by the Company’s credit risk personnel. Accordingly, for real estate collateral securing larger nonaccrual commercial and industrial loans and commercial real estate loans, estimated collateral values are based on current appraisals and estimates of value. For non-real estate loans, collateral is assigned a discounted estimated liquidation value and, depending on the nature of the collateral, is verified through field exams or other procedures. In assessing collateral, real estate and non-real estate values are reduced by an estimate of selling costs.

For residential real estate loans, including home equity loans and lines of credit, the excess of the loan balance over the net realizable value of the property collateralizing the loan is charged-off when the loan becomes 150 days delinquent. That charge-off is based on recent indications of value from external parties that are generally obtained shortly after a loan becomes nonaccrual. Loans to consumers that file for bankruptcy are generally charged-off to estimated net collateral value shortly after the Company is notified of such filings. When evaluating individual home equity loans and lines of credit for charge off and for purposes of estimating losses in determining the allowance for credit losses, the Company gives consideration to the required repayment of any first lien positions related to collateral property.

Changes in the amount of the allowance for credit losses reflect the outcome of the procedures described herein, including the impact of changes in macroeconomic forecasts as compared with previous forecasts, as well as the impact of portfolio concentrations, imprecision in economic forecast, geopolitical conditions and other risk factors that might influence the loss estimation process.

The Company's reserve for off-balance sheet credit exposures was not material at December 31, 2023 and December 31, 2022.

Information with respect to loans and leases that were considered nonaccrual at the beginning and end of the reporting period and the interest income recognized on such loans for the years ended December 31, 2023, 2022 and 2021 follows.


	Amortized Cost with Allowance		Amortized Cost without Allowance		Total		Amortized Cost			Interest Income Recognized
(Dollars in millions)	December 31, 2023							January 1, 2023		Year Ended December 31, 2023
Commercial and industrial	$	397	$	273	$	670		$	504	$	22
Real estate:
Commercial		288		581		869			1,240		29
Residential builder and developer		3		—		3			1		—
Other commercial construction		71		100		171			125		2
Residential		81		134		215			272		15
Residential — limited documentation		19		36		55			78		2
Consumer:
Home equity lines and loans		42		39		81			85		7
Recreational finance		24		12		36			45		1
Automobile		9		5		14			40		—
Other		52		—		52			49		—
Total	$	986	$	1,180	$	2,166		$	2,439	$	78

(Dollars in millions)	December 31, 2022							January 1, 2022		Year Ended December 31, 2022
Commercial and industrial	$	212	$	292	$	504		$	371	$	26
Real estate:
Commercial		366		874		1,240			919		14
Residential builder and developer		1		—		1			3		2
Other commercial construction		59		66		125			111		4
Residential		147		125		272			356		25
Residential — limited documentation		48		30		78			123		1
Consumer:
Home equity lines and loans		43		42		85			70		4
Recreational finance		37		8		45			28		1
Automobile		35		5		40			34		—
Other		49		—		49			45		—
Total	$	997	$	1,442	$	2,439		$	2,060	$	77

(Dollars in millions)	December 31, 2021							January 1, 2021		Year Ended December 31, 2021
Commercial and industrial	$	153	$	218	$	371		$	433	$	23
Real estate:
Commercial		199		720		919			650		5
Residential builder and developer		1		2		3			1		1
Other commercial construction		30		81		111			114		1
Residential		198		158		356			366		24
Residential — limited documentation		80		43		123			147		—
Consumer:
Home equity lines and loans		32		38		70			79		4
Recreational finance		22		6		28			26		1
Automobile		29		5		34			39		—
Other		45		—		45			38		—
Total	$	789	$	1,271	$	2,060		$	1,893	$	59

The Company utilizes a loan grading system to differentiate risk amongst its commercial and industrial loans and commercial real estate loans. Loans with a lower expectation of default are assigned one of ten possible “pass” loan grades and are generally ascribed lower loss factors when determining the allowance for credit losses. Loans with an elevated level of credit risk are classified as “criticized” and are ascribed a higher loss factor when determining the allowance for credit losses. Criticized loans may be classified as “nonaccrual” if the Company no longer expects to collect all amounts according to the contractual terms of the loan agreement or the loan is delinquent 90 days or more.

Line of business personnel in different geographic locations with support from and review by the Company’s credit risk personnel review and reassign loan grades based on their detailed knowledge of individual borrowers and their judgment of the impact on such borrowers resulting from changing conditions in their respective regions. Factors considered in assigning loan grades include borrower-specific information related to expected future cash flows and operating results, collateral values, geographic location, financial condition and performance, payment status, and other information. The Company’s policy is that, at least annually, updated financial information be obtained from commercial borrowers associated with pass grade loans and additional analysis performed. On a quarterly basis, the Company’s centralized credit risk department reviews all criticized commercial and industrial loans and commercial real estate loans greater than $5 million to determine the appropriateness of the assigned loan grade, including whether the loan should be reported as accruing or nonaccruing.

The following table summarizes the loan grades applied at December 31, 2023 to the various classes of the Company’s commercial and industrial loans and commercial real estate loans by origination year.


	Term Loans by Origination Year												Revolving		Revolving Loans Converted to Term
(Dollars in millions)	2023		2022		2021		2020		2019		Prior		Loans		Loans		Total
Commercial and industrial:
Loan grades:
Pass	$	8,689	$	8,087	$	4,800	$	2,248	$	2,169	$	4,843	$	22,345	$	70	$	53,251
Criticized accrual		292		279		277		142		127		481		1,460		31		3,089
Criticized nonaccrual		29		68		56		75		36		150		243		13		670
Total commercial and industrial	$	9,010	$	8,434	$	5,133	$	2,465	$	2,332	$	5,474	$	24,048	$	114	$	57,010
Gross charge-offs year ended December 31, 2023	$	10	$	45	$	18	$	13	$	10	$	19	$	17	$	—	$	132
Real estate:
Commercial:
Loan grades:
Pass	$	2,048	$	1,742	$	1,367	$	2,011	$	3,059	$	8,491	$	440	$	—	$	19,158
Criticized accrual		227		891		465		456		966		2,238		7		—		5,250
Criticized nonaccrual		—		46		3		113		93		611		3		—		869
Total commercial real estate	$	2,275	$	2,679	$	1,835	$	2,580	$	4,118	$	11,340	$	450	$	—	$	25,277
Gross charge-offs year ended December 31, 2023	$	—	$	—	$	—	$	—	$	112	$	129	$	—	$	—	$	241
Residential builder and developer:
Loan grades:
Pass	$	530	$	252	$	41	$	6	$	2	$	12	$	116	$	—	$	959
Criticized accrual		1		18		30		—		59		—		3		—		111
Criticized nonaccrual		—		—		3		—		—		—		—		—		3
Total residential builder and developer	$	531	$	270	$	74	$	6	$	61	$	12	$	119	$	—	$	1,073
Gross charge-offs year ended December 31, 2023	$	—	$	—	$	—	$	—	$	—	$	—	$	2	$	—	$	2
Other commercial construction:
Loan grades:
Pass	$	813	$	1,366	$	651	$	373	$	646	$	187	$	30	$	—	$	4,066
Criticized accrual		53		391		390		691		565		326		—		—		2,416
Criticized nonaccrual		—		14		10		46		50		49		2		—		171
Total other commercial construction	$	866	$	1,771	$	1,051	$	1,110	$	1,261	$	562	$	32	$	—	$	6,653
Gross charge-offs year ended December 31, 2023	$	—	$	—	$	—	$	—	$	3	$	7	$	—	$	—	$	10

The Company considers repayment performance a significant indicator of credit quality for its residential real estate loan and consumer loan portfolios. A summary of loans in accrual and nonaccrual status at December 31, 2023 for the various classes of the Company’s residential real estate loans and consumer loans by origination year is as follows:


	Term Loans by Origination Year												Revolving		Revolving Loans Converted to Term
(Dollars in millions)	2023		2022		2021		2020		2019		Prior		Loans		Loans		Total
Residential:
Current	$	1,726	$	4,709	$	3,732	$	2,543	$	1,215	$	7,060	$	95	$	—	$	21,080
30-89 days past due		18		120		88		52		28		457		—		—		763
Accruing loans past due 90 days or more		1		30		28		17		14		205		—		—		295
Nonaccrual		1		17		10		3		4		179		1		—		215
Total residential	$	1,746	$	4,876	$	3,858	$	2,615	$	1,261	$	7,901	$	96	$	—	$	22,353
Gross charge-offs year ended December 31, 2023	$	—	$	—	$	1	$	—	$	3	$	4	$	—	$	—	$	8
Residential - limited documentation:
Current	$	—	$	—	$	—	$	—	$	—	$	825	$	—	$	—	$	825
30-89 days past due		—		—		—		—		—		31		—		—		31
Accruing loans past due 90 days or more		—		—		—		—		—		—		—		—		—
Nonaccrual		—		—		—		—		—		55		—		—		55
Total residential - limited documentation	$	—	$	—	$	—	$	—	$	—	$	911	$	—	$	—	$	911
Gross charge-offs year ended December 31, 2023	$	—	$	—	$	—	$	—	$	—	$	2	$	—	$	—	$	2
Consumer:
Home equity lines and loans:
Current	$	—	$	—	$	2	$	2	$	13	$	98	$	3,022	$	1,391	$	4,528
30-89 days past due		—		—		—		—		—		3		—		37		40
Accruing loans past due 90 days or more		—		—		—		—		—		—		—		—		—
Nonaccrual		—		—		—		—		—		5		3		73		81
Total home equity lines and loans	$	—	$	—	$	2	$	2	$	13	$	106	$	3,025	$	1,501	$	4,649
Gross charge-offs year ended December 31, 2023	$	—	$	—	$	—	$	—	$	—	$	—	$	1	$	5	$	6
Recreational finance:
Current	$	2,653	$	2,338	$	1,857	$	1,286	$	781	$	1,020	$	—	$	—	$	9,935
30-89 days past due		11		16		19		14		11		16		—		—		87
Accruing loans past due 90 days or more		—		—		—		—		—		—		—		—		—
Nonaccrual		3		5		8		6		5		9		—		—		36
Total recreational finance	$	2,667	$	2,359	$	1,884	$	1,306	$	797	$	1,045	$	—	$	—	$	10,058
Gross charge-offs year ended December 31, 2023	$	4	$	13	$	14	$	12	$	9	$	16	$	—	$	—	$	68
Automobile:
Current	$	1,063	$	1,096	$	1,047	$	427	$	198	$	87	$	—	$	—	$	3,918
30-89 days past due		8		15		17		9		6		5		—		—		60
Accruing loans past due 90 days or more		—		—		—		—		—		—		—		—		—
Nonaccrual		2		3		3		2		2		2		—		—		14
Total automobile	$	1,073	$	1,114	$	1,067	$	438	$	206	$	94	$	—	$	—	$	3,992
Gross charge-offs year ended December 31, 2023	$	2	$	6	$	7	$	3	$	2	$	3	$	—	$	—	$	23
Other:
Current	$	250	$	176	$	118	$	33	$	13	$	18	$	1,392	$	3	$	2,003
30-89 days past due		3		3		2		—		—		1		20		1		30
Accruing loans past due 90 days or more		—		—		—		—		—		—		7		—		7
Nonaccrual		2		1		1		—		—		—		48		—		52
Total other	$	255	$	180	$	121	$	33	$	13	$	19	$	1,467	$	4	$	2,092
Gross charge-offs year ended December 31, 2023	$	18	$	17	$	7	$	3	$	3	$	10	$	20	$	—	$	78

Total loans and leases at December 31, 2023	$	18,423	$	21,683	$	15,025	$	10,555	$	10,062	$	27,464	$	29,237	$	1,619	$	134,068
Total gross charge-offs for the year ended December 31, 2023	$	34	$	81	$	47	$	31	$	142	$	190	$	40	$	5	$	570

The following table summarizes the loan grades applied at December 31, 2022 to the various classes of the Company’s commercial and industrial loans and commercial real estate loans by origination year.


	Term Loans by Origination Year												Revolving		Revolving Loans Converted to Term
(Dollars in millions)	2022		2021		2020		2019		2018		Prior		Loans		Loans		Total
Commercial and industrial:
Loan grades:
Pass	$	10,217	$	6,582	$	3,110	$	2,989	$	1,752	$	4,615	$	19,794	$	41	$	49,100
Criticized accrual		259		237		234		170		98		527		774		17		2,316
Criticized nonaccrual		21		55		67		51		55		147		101		7		504
Total commercial and industrial	$	10,497	$	6,874	$	3,411	$	3,210	$	1,905	$	5,289	$	20,669	$	65	$	51,920

Real estate:
Commercial:
Loan grades:
Pass	$	2,493	$	1,752	$	2,303	$	3,365	$	2,359	$	8,262	$	521	$	—	$	21,055
Criticized accrual		314		449		424		635		910		1,610		42		—		4,384
Criticized nonaccrual		9		19		155		282		151		601		23		—		1,240
Total commercial real estate	$	2,816	$	2,220	$	2,882	$	4,282	$	3,420	$	10,473	$	586	$	—	$	26,679

Residential builder and developer:
Loan grades:
Pass	$	682	$	230	$	11	$	22	$	13	$	10	$	150	$	—	$	1,118
Criticized accrual		3		28		10		109		15		—		31		—		196
Criticized nonaccrual		—		1		—		—		—		—		—		—		1
Total residential builder and developer	$	685	$	259	$	21	$	131	$	28	$	10	$	181	$	—	$	1,315

Other commercial construction:
Loan grades:
Pass	$	1,033	$	1,080	$	1,226	$	1,186	$	367	$	296	$	16	$	—	$	5,204
Criticized accrual		38		145		321		1,025		299		145		—		—		1,973
Criticized nonaccrual		—		10		44		36		11		22		2		—		125
Total other commercial construction	$	1,071	$	1,235	$	1,591	$	2,247	$	677	$	463	$	18	$	—	$	7,302

A summary of loans in accrual and nonaccrual status at December 31, 2022 for the various classes of the Company’s residential real estate loans and consumer loans by origination year follows.


	Term Loans by Origination Year												Revolving		Revolving Loans Converted to Term
(Dollars in millions)	2022		2021		2020		2019		2018		Prior		Loans		Loans		Total
Residential:
Current	$	5,071	$	4,002	$	2,717	$	1,393	$	754	$	7,524	$	31	$	—	$	21,492
30-89 days past due		60		51		40		22		23		399		1		—		596
Accruing loans past due 90 days or more		12		40		20		14		14		245		—		—		345
Nonaccrual		6		11		3		10		5		231		6		—		272
Total residential	$	5,149	$	4,104	$	2,780	$	1,439	$	796	$	8,399	$	38	$	—	$	22,705

Residential - limited documentation:
Current	$	—	$	—	$	—	$	—	$	—	$	951	$	—	$	—	$	951
30-89 days past due		—		—		—		—		—		22		—		—		22
Accruing loans past due 90 days or more		—		—		—		—		—		—		—		—		—
Nonaccrual		—		—		—		—		—		78		—		—		78
Total residential - limited documentation	$	—	$	—	$	—	$	—	$	—	$	1,051	$	—	$	—	$	1,051

Consumer:
Home equity lines and loans:
Current	$	1	$	2	$	2	$	15	$	23	$	97	$	3,264	$	1,487	$	4,891
30-89 days past due		—		—		—		—		1		2		—		28		31
Accruing loans past due 90 days or more		—		—		—		—		—		—		—		—		—
Nonaccrual		—		—		—		1		—		6		3		75		85
Total home equity lines and loans	$	1	$	2	$	2	$	16	$	24	$	105	$	3,267	$	1,590	$	5,007

Recreational finance:
Current	$	2,842	$	2,281	$	1,588	$	964	$	487	$	812	$	—	$	—	$	8,974
30-89 days past due		9		10		12		8		5		11		—		—		55
Accruing loans past due 90 days or more		—		—		—		—		—		—		—		—		—
Nonaccrual		3		7		9		8		6		12		—		—		45
Total recreational finance	$	2,854	$	2,298	$	1,609	$	980	$	498	$	835	$	—	$	—	$	9,074

Automobile:
Current	$	1,491	$	1,558	$	703	$	379	$	167	$	95	$	—	$	—	$	4,393
30-89 days past due		7		13		7		7		6		4		—		—		44
Accruing loans past due 90 days or more		—		—		—		—		—		—		—		—		—
Nonaccrual		2		11		7		8		6		6		—		—		40
Total automobile	$	1,500	$	1,582	$	717	$	394	$	179	$	105	$	—	$	—	$	4,477

Other:
Current	$	274	$	173	$	58	$	39	$	8	$	23	$	1,374	$	8	$	1,957
30-89 days past due		4		1		—		—		—		1		16		1		23
Accruing loans past due 90 days or more		—		—		—		—		—		—		5		—		5
Nonaccrual		3		1		—		—		—		—		45		—		49
Total other	$	281	$	175	$	58	$	39	$	8	$	24	$	1,440	$	9	$	2,034

Total loans and leases at December 31, 2022	$	24,854	$	18,749	$	13,071	$	12,738	$	7,535	$	26,754	$	26,199	$	1,664	$	131,564

Capitalized Servicing Assets - Changes in Capitalized Servicing Assets (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Residential Mortgage Loans [Member]
Servicing Asset at Amortized Cost [Line Items]
Amortized value, Beginning balance	$ 194	$ 241	$ 231
Originations	13	7	66
Purchases	350
Acquired in business combination		12
Amortization	(101)	(66)	(56)
Amortized value, ending balance	456	194	241
Valuation allowance			(24)
Ending balance, net	456	194	217
Total loans serviced for others	155,342	118,392
Residential Mortgage Loans [Member] \| Loans Serviced for Others [Member]
Servicing Asset at Amortized Cost [Line Items]
Total loans serviced for others	40,021	22,365
Residential Mortgage Loans [Member] \| Loans Sub-serviced for Others [Member]
Servicing Asset at Amortized Cost [Line Items]
Total loans serviced for others	115,321	96,027
Commercial Mortgage Loans [Member]
Servicing Asset at Amortized Cost [Line Items]
Amortized value, Beginning balance	126	133	134
Originations	27	24	33
Amortization	(30)	(31)	(34)
Amortized value, ending balance	123	126	133
Ending balance, net	123	126	$ 133
Total loans serviced for others	28,030	26,007
Commercial Mortgage Loans [Member] \| Loans Serviced for Others [Member]
Servicing Asset at Amortized Cost [Line Items]
Total loans serviced for others	24,157	22,166
Commercial Mortgage Loans [Member] \| Loans Sub-serviced for Others [Member]
Servicing Asset at Amortized Cost [Line Items]
Total loans serviced for others	$ 3,873	$ 3,841

Derivative financial instruments

12 Months Ended

Dec. 31, 2023

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Derivative financial instruments

19. Derivative financial instruments

As part of managing interest rate risk, the Company enters into interest rate swap agreements to modify the repricing characteristics of certain portions of the Company’s portfolios of earning assets and interest-bearing liabilities. The Company designates interest rate swap agreements utilized in the management of interest rate risk as either fair value hedges or cash flow hedges. Interest rate swap agreements are generally entered into with counterparties that meet established credit standards and most contain master netting, collateral and/or settlement provisions protecting the at-risk party. Based on adherence to the Company’s credit standards and the presence of the netting, collateral or settlement provisions, the Company believes that the credit risk inherent in these contracts was not material as of December 31, 2023.

The net effect of interest rate swap agreements was to decrease net interest income by $302 million in 2023 and $26 million in 2022 and to increase net interest income by $287 million in 2021.

Information about interest rate swap agreements entered into for interest rate risk management purposes summarized by type of financial instrument the interest rate swap agreements were intended to hedge follows:


			Average		Weighted-						Estimated
	Notional		Maturity		Average Rate						Fair Value
(Dollars in millions)	Amount		(In years)		Fixed			Variable			Gain (Loss) (a)
December 31, 2023
Fair value hedges:
Fixed rate long-term borrowings (b) (c)	$	3,000		5.8		3.45	%		5.62	%	$	(1	)
Cash flow hedges:
Interest payments on variable rate commercial real estate loans (b) (d)		23,977		1.7	3.45			5.36				11
Total	$	26,977		2.2							$	10
December 31, 2022
Fair value hedges:
Fixed rate long-term borrowings (b)	$	1,500		3.3		2.98	%		4.52	%	$	(1	)
Cash flow hedges:
Interest payments on variable rate commercial real estate loans (b) (e)		15,900		1.4	1.91			4.38				(7	)
Total	$	17,400		1.6							$	(8	)

(a)

Certain clearinghouse exchanges consider payments by counterparties for variation margin on derivative instruments to be settlements of those positions. The impact of such payments for interest rate swap agreements designated as fair value hedges was a net settlement of losses of $43 million at December 31, 2023 and a net settlement of losses of $65 million at December 31, 2022. The impact of such payments on interest rate swap agreements designated as cash flow hedges was a net settlement of losses of $214 million at December 31, 2023 and a net settlement of losses of $330 million at December 31, 2022.

(b)

Under the terms of these agreements, the Company receives settlement amounts at a fixed rate and pays at a variable rate.

(c)

Includes notional amount and terms of $1.0 billion of forward-starting interest rate swap agreements that become effective in 2025.

(d)

Includes notional amount and terms of $9.0 billion of forward-starting interest rate swap agreements that become effective in 2024.

(e)

Includes notional amount and terms of $4.7 billion of forward-starting interest rate swap agreements that became effective in 2023.

The notional amount of interest rate swap agreements entered into for risk management purposes that were outstanding at December 31, 2023 mature as follows:


(Dollars in millions)
Year ending December 31:
2024	$	3,158
2025		10,369
2026		10,450
2027		1,000
2028		1,000
2033		1,000
	$	26,977

The Company also has commitments to sell and commitments to originate residential and commercial real estate loans that are considered derivatives. The Company designates certain of the commitments to sell real estate loans as fair value hedges of real estate loans held for sale. The Company also utilizes commitments to sell real estate loans to offset the exposure to changes in the fair value of certain commitments to originate real estate loans for sale. Changes in unrealized gains and losses are included in mortgage banking revenues and, in general, are realized in subsequent periods as the related loans are sold and commitments satisfied.

Other derivative financial instruments not designated as hedging instruments included interest rate contracts, foreign exchange and other option and futures contracts. Interest rate contracts not designated as hedging instruments had notional values of $44.4 billion and $45.1 billion at December 31, 2023 and 2022, respectively. The notional amounts of foreign currency and other option and futures contracts not designated as hedging instruments aggregated $1.5 billion and $1.7 billion at December 31, 2023 and 2022, respectively.

Information about the fair values of derivative instruments in the Company’s Consolidated Balance Sheet and Consolidated Statement of Income follows:


	Asset Derivatives				Liability Derivatives
	Fair Value				Fair Value
	December 31,		December 31,		December 31,		December 31,
(Dollars in millions)	2023		2022		2023		2022
Derivatives designated and qualifying as hedging instruments (a)
Interest rate swap agreements	$	12	$	1	$	2	$	9
Commitments to sell real estate loans		6		3		8		—
		18		4		10		9
Derivatives not designated and qualifying as hedging instruments (a)
Mortgage banking:
Commitments to originate real estate loans for sale		15		—		32		46
Commitments to sell real estate loans		35		51		3		—
		50		51		35		46
Other:
Interest rate contracts (b)		237		356		879		1,278
Foreign exchange and other option and futures contracts		19		24		19		22
		256		380		898		1,300
Total derivatives	$	324	$	435	$	943	$	1,355

(a)

Asset derivatives are reported in "accrued interest and other assets" and liability derivatives are reported in "accrued interest and other liabilities".

(b)

The impact of variation margin payments at December 31, 2023 and 2022 was a reduction of the estimated fair value of interest rate contracts not designated as hedging instruments in an asset position of $783 million and $1.1 billion, respectively, and in a liability position of $32 million and $29 million, respectively.


	Amount of Gain (Loss) Recognized
	Year ended December 31,
	2023					2022					2021
(Dollars in millions)	Derivative		Hedged Item			Derivative			Hedged Item		Derivative			Hedged Item
Derivatives in fair value hedging relationships
Interest rate swap agreements:
Fixed rate long-term borrowings (a)	$	22	$	(21	)	$	(109	)	$	109	$	(59	)	$	58
Derivatives not designated as hedging instruments
Interest rate contracts (b)	$	31				$	28				$	12
Foreign exchange and other option and futures contracts (b)		15					14					9
Total	$	46				$	42				$	21

(a)

Reported as an adjustment to "interest expense" in the Consolidated Statement of Income.

(b)

Reported as "trading account and other non-hedging derivative gains" in the Consolidated Statement of Income.


	Carrying Amount of the Hedged Item				Cumulative Amount of Fair Value Hedging Adjustment Increasing (Decreasing) the Carrying Amount of the Hedged Item
(Dollars in millions)	December 31, 2023		December 31, 2022		December 31, 2023			December 31, 2022
Location in the Consolidated Balance Sheet of the Hedged Items in Fair Value Hedges
Long-term borrowings	$	2,954	$	1,434	$	(44	)	$	(65	)

The amount of interest income recognized in the Consolidated Statement of Income associated with derivatives designated as cash flow hedges was a decrease of $250 million for 2023 and a decrease of $36 million for 2022. As of December 31, 2023, the unrealized loss recognized in other comprehensive income related to cash flow hedges was $203 million, of which losses of $5 million and $211 million and gains of $13 million relate to interest rate swap agreements maturing in 2024, 2025 and 2026, respectively.

The Company does not offset derivative asset and liability positions in its consolidated financial statements. The Company’s exposure to credit risk by entering into derivative contracts is mitigated through master netting agreements and collateral posting or settlement requirements. Master netting agreements covering interest rate and foreign exchange contracts with the same party include a right to set-off that becomes enforceable in the event of default, early termination or under other specific conditions.

The aggregate fair value of derivative financial instruments in a liability position, which are subject to enforceable master netting arrangements, and the related collateral posted, was not material at each of December 31, 2023 and 2022. Certain of the Company’s derivative financial instruments contain provisions that require the Company to maintain specific credit ratings from credit rating agencies to avoid higher collateral posting requirements. If the Company’s debt ratings were to fall below specified ratings, the counterparties of the derivative financial instruments could demand immediate incremental collateralization on those instruments in a net liability position. The aggregate fair value of all derivative financial instruments with such credit risk-related contingent features in a net liability position on December 31, 2023 was not material.

The aggregate fair value of derivative financial instruments in an asset position with counterparties, which are subject to enforceable master netting arrangements, was $179 million and $314 million at December 31, 2023 and 2022, respectively. Counterparties posted collateral relating to those positions of $179 million and $312 million at December 31, 2023 and 2022, respectively. Interest

rate swap agreements entered into with customers are subject to the Company’s credit risk standards and often contain collateral provisions.

In addition to the derivative contracts noted above, the Company clears certain derivative transactions through a clearinghouse, rather than directly with counterparties. Those transactions cleared through a clearinghouse require initial margin collateral and variation margin payments depending on the contracts being in a net asset or liability position. The amount of initial margin collateral posted by the Company was $129 million and $205 million at December 31, 2023 and 2022, respectively. The fair value asset and liability amounts of derivative contracts have been reduced by variation margin payments treated as settlements as described herein. Variation margin on derivative contracts not treated as settlements continues to represent collateral posted or received by the Company.

Loans and Leases - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Loans And Leases Receivable [Line Items]
Amount of foreclosed residential real estate property held	$ 39	$ 41
Loans secured by residential real estate that were in the process of foreclosure	$ 170	201
Percentage loans in the process of foreclosure, serviced by other entities, classified as government guaranteed	35.00%
Guaranteed amount included in the estimated residual value of leased assets associated with financing leases	$ 96	93
Financing Receivable, Troubled Debt Restructuring, Postmodification		280	$ 529
Remaining balance of loans and leases	$ 134,936	132,074
Residential Real Estate Loans [Member]
Loans And Leases Receivable [Line Items]
Weighted-average remaining term	10 years 7 months 6 days
Payment Deferral [Member]
Loans And Leases Receivable [Line Items]
Financing Receivable, Troubled Debt Restructuring, Postmodification		203	$ 247
Director and Certain Officers [Member]
Loans And Leases Receivable [Line Items]
Exclusion limit of loans from related party disclosure	less than $60,000
Borrowing by directors and certain officers of M&T and its banking subsidiaries and their associates	$ 116	102
New borrowings by directors, certain officers and their associates	49
Repayments and other reductions of borrowings by directors, certain officers and their associates	35
Residential Mortgage Loans [Member] \| Asset Pledged as Collateral without Right [Member] \| FHLBs Facility [Member]
Loans And Leases Receivable [Line Items]
Pledged financial instruments	18,800
Residential Mortgage Loans [Member] \| One-to-Four Family Residential [Member]
Loans And Leases Receivable [Line Items]
Mortgage loans held for sale	190	32
Commercial Real Estate Loans [Member] \| Asset Pledged as Collateral without Right [Member] \| FHLBs Facility [Member]
Loans And Leases Receivable [Line Items]
Pledged financial instruments	16,400
Commercial Real Estate Loans [Member] \| One-to-Four Family Residential [Member]
Loans And Leases Receivable [Line Items]
Mortgage loans held for sale	$ 189	$ 131
Commercial and Industrial [Member]
Loans And Leases Receivable [Line Items]
Weighted-average remaining term	1 year 3 months 18 days
Residential Builder and Developer [Member]
Loans And Leases Receivable [Line Items]
Weighted-average remaining term	1 year 1 month 6 days
Other Commercial Construction [Member]
Loans And Leases Receivable [Line Items]
Weighted-average remaining term	1 year 1 month 6 days
Commercial and Industrial Loans [Member] \| Asset Pledged as Collateral without Right [Member] \| FHLBs Facility [Member]
Loans And Leases Receivable [Line Items]
Pledged financial instruments	$ 13,400
Home Equity Loans and Lines of Credit [Member] \| Asset Pledged as Collateral without Right [Member] \| FHLBs Facility [Member]
Loans And Leases Receivable [Line Items]
Pledged financial instruments	2,600
Asset-Backed Securities [Member]
Loans And Leases Receivable [Line Items]
Remaining balance of loans and leases	599
Other Consumer Loans [Member] \| Asset Pledged as Collateral without Right [Member] \| FHLBs Facility [Member]
Loans And Leases Receivable [Line Items]
Pledged financial instruments	$ 11,000

Relationship with BLG and Bayview Financial

12 Months Ended

Dec. 31, 2023

Text Block [Abstract]

Relationship with BLG and Bayview Financial

25. Relationship with BLG and Bayview Financial

M&T holds a 20% minority interest in BLG, a privately-held commercial mortgage company. That investment had no remaining carrying value at December 31, 2023 as a result of cumulative losses recognized and cash distributions received in prior years. Cash distributions now received from BLG are recognized as income by M&T and included in other revenues from operations. That income totaled $20 million in 2023, compared with $30 million in each of 2022 and 2021.

Bayview Financial, a privately-held specialty finance company, is BLG’s majority investor. In addition to their common investment in BLG, the Company and Bayview Financial conduct other business activities with each other. The Company has obtained loan servicing rights for mortgage loans from BLG and Bayview Financial having outstanding principal balances of $1.2 billion and $1.4 billion at December 31, 2023 and 2022, respectively. Revenues from those servicing rights were $6 million, $8 million and $9 million during 2023, 2022 and 2021, respectively. The Company sub-services residential mortgage loans for Bayview Financial having outstanding principal balances of $115.3 billion and $96.0 billion at December 31, 2023 and 2022, respectively. Revenues earned for sub-servicing loans for Bayview Financial were $125 million, $154 million and $153 million in 2023,

2022 and 2021, respectively. In addition, the Company held $42 million and $50 million of mortgage-backed securities in its held-to-maturity portfolio at December 31, 2023 and 2022, respectively, that were securitized by Bayview Financial. At December 31, 2023, the Company held $672 million of Bayview Financial’s $3.2 billion syndicated loan facility. In 2021 the Company purchased $965 million of delinquent government guaranteed mortgage loans, including past due accrued interest, from Bayview Financial for $1.0 billion. The servicing rights for such loans were retained by Bayview Financial, but the Company continues to sub-service the loans.

Loans and Leases - Loan Modification Activities to Borrowers Experiencing Financial Difficulty on Financing Receivables (Parenthetical) (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($)
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]
Financing receivable, modifications other than troubled debt restructuring	$ 1,586
Unfunded Commitments to Extend Credit [Member]
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]
Financing receivable, modifications other than troubled debt restructuring	128
Guaranteed by Government-Related Entities [Member]
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]
Financing receivable, modifications other than troubled debt restructuring	$ 124

Pension Plans and Other Postretirement Benefits - Changes in Level 3 Pension Plan Assets Measured at Fair Value on Recurring Basis (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($)
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of plan assets at beginning of year	$ 2,938
Fair value of plan assets at end of year	3,141
Significant Unobservable Inputs (Level 3) [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of plan assets at beginning of year	408
Fair value of plan assets at end of year	444
Real Estate Partnerships [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of plan assets at beginning of year	20
Purchase(Sales)	2
Fair value of plan assets at end of year	22
Private Equity/Debt [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of plan assets at beginning of year	211
Purchase(Sales)	12
Realized/Unrealized Gains (Losses)	12
Fair value of plan assets at end of year	235
Hedge Funds [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of plan assets at beginning of year	276
Fair value of plan assets at end of year	285
Hedge Funds [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of plan assets at beginning of year	167
Realized/Unrealized Gains (Losses)	11
Fair value of plan assets at end of year	178
Guaranteed Deposit Fund [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of plan assets at beginning of year	10
Fair value of plan assets at end of year	9
Guaranteed Deposit Fund [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of plan assets at beginning of year	10
Realized/Unrealized Gains (Losses)	(1)
Fair value of plan assets at end of year	9
Securities [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of plan assets at beginning of year	408
Purchase(Sales)	14
Realized/Unrealized Gains (Losses)	22
Fair value of plan assets at end of year	$ 444

Borrowings - Additional Information (Detail) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Aug. 31, 2023	Dec. 31, 2023	Dec. 31, 2021	Dec. 31, 2022
Debt Instrument [Line Items]
Outstanding borrowings		$ 5,000
Debt Maturity, Start Year			Jan. 01, 2027
Debt Maturity, End Year			Dec. 31, 2033
Asset-backed notes		$ 474
Minimum [Member]
Debt Instrument [Line Items]
Variable interest rate of Senior Notes /Junior Subordinated Debentures		6.49%		5.08%
Maximum [Member]
Debt Instrument [Line Items]
Variable interest rate of Senior Notes /Junior Subordinated Debentures		9.01%		7.69%
FHLBs Facility [Member]
Debt Instrument [Line Items]
Borrowing facilities available with FHLB's amount		$ 16,800
Federal Reserve Bank of New York [Member]
Debt Instrument [Line Items]
Line of credit facility		$ 17,100
Senior Notes Issued in July 2018 [Member]
Debt Instrument [Line Items]
Variable interest rate of Senior Notes /Junior Subordinated Debentures				5.00%
Junior Subordinated Debt [Member]
Debt Instrument [Line Items]
Weighted-average interest rate		7.07%		5.66%
Short-term Borrowings [Member]
Debt Instrument [Line Items]
Stated maturity		1 year
Equipment Finance Loan [Member]
Debt Instrument [Line Items]
Weighted-average interest rate	5.89%
Asset-backed notes	$ 550
Weighted-average estimated life	2 years

Fair Value Measurements - Assets and Liabilities Measured at Estimated Fair Value on Recurring Basis (Detail) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Debt Securities, Available-for-Sale	$ 10,440	$ 10,749
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Trading account	101	118
Significant Observable Inputs (Level 2) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Trading account	5
U.S. Treasury and Federal Agencies [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Debt Securities, Available-for-Sale	7,705	7,671
Commercial Mortgage-Backed Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Debt Securities, Available-for-Sale	416	574
Residential Mortgage-Backed Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Debt Securities, Available-for-Sale	2,154	2,330
Other Debt Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Debt Securities, Available-for-Sale	165	174
Fair Value Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Trading account	106	118
Debt Securities, Available-for-Sale	10,440	10,749
Equity Securities, FV-NI, Current	268	151
Real estate loans held for sale	379	162
Other assets	324	435
Total assets	11,517	11,615
Other liabilities	943	1,355
Total liabilities	943	1,355
Fair Value Measurements, Recurring [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Trading account	101	118
Equity Securities, FV-NI, Current	258	145
Total assets	359	263
Fair Value Measurements, Recurring [Member] \| Significant Observable Inputs (Level 2) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Trading account	5
Debt Securities, Available-for-Sale	10,440	10,749
Equity Securities, FV-NI, Current	10	6
Real estate loans held for sale	379	162
Other assets	309	435
Total assets	11,143	11,352
Other liabilities	911	1,309
Total liabilities	911	1,309
Fair Value Measurements, Recurring [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Other assets	15
Total assets	15
Other liabilities	32	46
Total liabilities	32	46
Fair Value Measurements, Recurring [Member] \| U.S. Treasury and Federal Agencies [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Debt Securities, Available-for-Sale	7,705	7,671
Fair Value Measurements, Recurring [Member] \| U.S. Treasury and Federal Agencies [Member] \| Significant Observable Inputs (Level 2) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Debt Securities, Available-for-Sale	7,705	7,671
Fair Value Measurements, Recurring [Member] \| Commercial Mortgage-Backed Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Debt Securities, Available-for-Sale	416	574
Fair Value Measurements, Recurring [Member] \| Commercial Mortgage-Backed Securities [Member] \| Significant Observable Inputs (Level 2) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Debt Securities, Available-for-Sale	416	574
Fair Value Measurements, Recurring [Member] \| Residential Mortgage-Backed Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Debt Securities, Available-for-Sale	2,154	2,330
Fair Value Measurements, Recurring [Member] \| Residential Mortgage-Backed Securities [Member] \| Significant Observable Inputs (Level 2) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Debt Securities, Available-for-Sale	2,154	2,330
Fair Value Measurements, Recurring [Member] \| Other Debt Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Debt Securities, Available-for-Sale	165	174
Fair Value Measurements, Recurring [Member] \| Other Debt Securities [Member] \| Significant Observable Inputs (Level 2) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Debt Securities, Available-for-Sale	$ 165	$ 174

Borrowings - Maturity of Long-term Borrowings (Detail) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Debt Disclosure [Abstract]
2024	$ 527
2025	1,251
2026	1,297
2027	775
2028	1,728
Later years	2,623
Long-term borrowings	$ 8,201	$ 3,965

- Definition

Amount, after deduction of unamortized premium (discount) and debt issuance cost, of long-term debt. Excludes lease obligation.

+ References + Details

Goodwill and other intangible assets

12 Months Ended

Dec. 31, 2023

Goodwill and Intangible Assets Disclosure [Abstract]

Goodwill and other intangible assets

8. Goodwill and other intangible assets

The Company does not amortize goodwill, however, core deposit and other intangible assets are amortized over the estimated life of each respective asset. A summary of total amortizing intangible assets follows.


(Dollars in millions)	Gross Carrying Amount		Accumulated Amortization		Net Carrying Amount
December 31, 2023
Core deposit	$	218	$	90	$	128
Other		43		24		19
Total	$	261	$	114	$	147
December 31, 2022
Core deposit	$	218	$	41	$	177
Other		43		11		32
Total	$	261	$	52	$	209

Amortization of core deposit and other intangible assets was generally computed using accelerated methods over original amortization periods of three to seven years. The weighted-average original amortization period was approximately six years. Amortization expense for core deposit and other intangible assets was $62 million, $56 million and $10 million for the years ended December 31, 2023, 2022 and 2021, respectively. Estimated amortization expense in future years for such intangible assets is as follows:


(Dollars in millions)
Year ending December 31:
2024	$	53
2025		38
2026		27
2027		18
2028		9
Later years		2
	$	147

The Company completed its annual goodwill impairment test as of October 1, 2023. For purposes of testing for impairment, the Company assigned all recorded goodwill to the reporting units originally intended to benefit from past business combinations, which has historically been the Company’s core relationship business reporting units. Goodwill was generally assigned based on the implied fair value of the acquired goodwill applicable to the benefited reporting units at the time of each respective acquisition. The implied fair value of the goodwill was determined as the difference between the estimated incremental overall fair value of the reporting unit and the estimated fair value of the net

assets assigned to the reporting unit as of each respective acquisition date. There were no changes to the goodwill assigned to any business reporting unit as a result of the realignment of the Company's business operations into three reportable segments in the fourth quarter of 2023 as described in note 23. To test for goodwill impairment at the evaluation date, the Company compared the estimated fair value of each of its reporting units to their respective carrying amounts and certain other assets and liabilities assigned to the reporting unit, including goodwill and core deposit and other intangible assets. The methodologies used to estimate fair values of reporting units as of the acquisition dates and as of the evaluation date were similar. For the Company’s core customer relationship business reporting units, fair value was estimated as the present value of the expected future cash flows of the reporting unit. Based on the results of the goodwill impairment test, the Company concluded that the amount of recorded goodwill was not impaired at the testing date. The Company was not aware of any events occurring in the fourth quarter of 2023 that more likely than not would have resulted in an impairment of recorded goodwill at December 31, 2023.

A summary of goodwill assigned to each of the Company’s reportable segments as of December 31, 2023 and 2022 for purposes of testing for impairment is as follows:


	December 31,		2023			December 31,
(Dollars in millions)	2022		Transactions (a)			2023
Commercial Bank	$	5,076	$	—		$	5,076
Retail Bank		3,089		—			3,089
Institutional Services & Wealth Management		325		(25	)		300
All Other		—		—			—
Total	$	8,490	$	(25	)	$	8,465

(a)

The decrease in Institutional Services & Wealth Management represents goodwill allocated to the CIT business sold in April 2023. Further information regarding that transaction is provided in note 2.

Other income and other expense

12 Months Ended

Dec. 31, 2023

Other Income and Expenses [Abstract]

Other income and other expense

17. Other income and other expense


	Year Ended December 31,
(Dollars in millions)	2023		2022		2021
Other revenues from operations:
Gain on divestiture of CIT	$	225
Credit-related fee income		151	$	130	$	91
Gain on divestiture of MTIA				136
Credit card interchange fee income						70
Merchant discount fee income						61
Other costs of operations:
Amortization of capitalized mortgage servicing rights		131		97		90
Charitable contributions				178

Shareholders' Equity - Issued and Outstanding Preferred Stock (Detail) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Class Of Stock [Line Items]
Preferred stock, Shares Issued	10,000,000	10,000,000
Carrying Value	$ 2,011	$ 2,011
Series E Fixed-To-Floating Rate Non-Cumulative Perpetual Preferred Stock [Member]
Class Of Stock [Line Items]
Preferred stock, Shares Issued	350,000	350,000
Preferred stock, Shares Outstanding	350,000	350,000
Carrying Value	$ 350	$ 350
Series F Fixed-to-Floating Rate Non-Cumulative Perpetual Preferred Stock [Member]
Class Of Stock [Line Items]
Preferred stock, Shares Issued	50,000	50,000
Preferred stock, Shares Outstanding	50,000	50,000
Carrying Value	$ 500	$ 500
Series G Fixed-Rate Reset Non-Cumulative Perpetual Preferred Stock [Member]
Class Of Stock [Line Items]
Preferred stock, Shares Issued	40,000	40,000
Preferred stock, Shares Outstanding	40,000	40,000
Carrying Value	$ 400	$ 400
Series H Fixed-to-Floating Rate Non-cumulative Perpetual Preferred Stock [Member]
Class Of Stock [Line Items]
Preferred stock, Shares Issued	10,000,000	10,000,000
Preferred stock, Shares Outstanding	10,000,000	10,000,000
Carrying Value	$ 261	$ 261
Series I Fixed-Rate Reset Non-Cumulative Perpetual Preferred Stock [Member]
Class Of Stock [Line Items]
Preferred stock, Shares Issued	50,000	50,000
Preferred stock, Shares Outstanding	50,000	50,000
Carrying Value	$ 500	$ 500

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 2: http://www.xbrl.org/2003/role/recommendedDisclosureRef
-Topic 272
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483014/272-10-45-3

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 272
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482987/272-10-50-1

Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(d))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480678/235-10-S99-1

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (e)
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-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (h)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 14
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-14

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 18
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-18

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 210
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-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(27)(b))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(28))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-2

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(29))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1

Reference 15: http://www.xbrl.org/2003/role/disclosureRef
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Reference 16: http://www.xbrl.org/2003/role/disclosureRef
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-Paragraph 3
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Reference 17: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 3
-Subparagraph (SX 210.6-03(i)(2)(i))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479886/946-10-S99-3

Reference 18: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 3
-Subparagraph (SX 210.6-03(i)(2)(ii))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479886/946-10-S99-3

+ Details

Allowance for Credit Losses - Changes in Allowance for Credit Losses (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	$ 1,925	$ 1,469	$ 1,736
Allowance on acquired PCD loans		99
Provision for credit losses	645	517	(75)
Net charge-offs:
Charge-offs	(570)	(303)	(338)
Recoveries	129	143	146
Net charge-offs	(441)	(160)	(192)
Ending balance	2,129	1,925	1,469
Commercial and Industrial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	568	335	469
Allowance on acquired PCD loans		48
Provision for credit losses	132	244	(58)
Net charge-offs:
Charge-offs	(132)	(119)	(124)
Recoveries	52	60	48
Net charge-offs	(80)	(59)	(76)
Ending balance	620	568	335
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	611	506	607
Allowance on acquired PCD loans		49
Provision for credit losses	394	93	(25)
Net charge-offs:
Charge-offs	(253)	(60)	(100)
Recoveries	12	23	24
Net charge-offs	(241)	(37)	(76)
Ending balance	764	611	506
One-to-Four Family Residential [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	115	72	104
Allowance on acquired PCD loans		2
Provision for credit losses	4	43	(30)
Net charge-offs:
Charge-offs	(10)	(12)	(11)
Recoveries	7	10	9
Net charge-offs	(3)	(2)	(2)
Ending balance	116	115	72
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	631	556	556
Provision for credit losses	115	137	38
Net charge-offs:
Charge-offs	(175)	(112)	(103)
Recoveries	58	50	65
Net charge-offs	(117)	(62)	(38)
Ending balance	$ 629	$ 631	$ 556

Pension Plans and Other Postretirement Benefits - Net Periodic Benefit Cost for Defined Benefit Plans (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 11	$ 18	$ 20
Interest cost on benefit obligation	115	82	62
Expected return on plan assets	(201)	(188)	(143)
Amortization of prior service cost (credit)		1	1
Recognized net actuarial (gain) loss	(2)	20	89
Net periodic pension (benefit) cost	$ (77)	$ (67)	$ 29
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Excluding Service Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Noninterest Expense	Other Noninterest Expense	Other Noninterest Expense
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Amortization of Prior Service Cost (Credit), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Noninterest Expense	Other Noninterest Expense	Other Noninterest Expense
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 2	$ 3	$ 1
Interest cost on benefit obligation	3	2	1
Amortization of prior service cost (credit)	(2)	(3)	(5)
Recognized net actuarial (gain) loss	$ (3)	(1)	(1)
Net periodic pension (benefit) cost		$ 1	$ (4)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Excluding Service Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Noninterest Expense	Other Noninterest Expense	Other Noninterest Expense
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Amortization of Prior Service Cost (Credit), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Noninterest Expense	Other Noninterest Expense	Other Noninterest Expense

Acquisition and Divestitures - Summary of Unpaid Principal Balance to Fair Value of PCD Loans and Leases by Portfolio Segment (Parenthetical) (Details) - USD ($) $ in Millions		12 Months Ended
	Apr. 01, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Accounts, Notes, Loans and Financing Receivable [Line Items]
Charge-offs		$ (570)	$ (303)	$ (338)
PCD Acquired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Charge-offs	$ (33)
Non PCD Acquired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Charge-offs	$ (242)

Relationship with BLG and Bayview Financial - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Schedule of Equity Method Investments [Line Items]
Loan facility carrying amount	$ 8,201,000,000	$ 3,965,000,000
Bayview Lending Group [Member]
Schedule of Equity Method Investments [Line Items]
Minority interest in Bayview Lending Group LLC	20.00%
Carrying value of minority interest investment in Bayview Lending Group LLC	$ 0
Bayview Lending Group [Member] \| Other Revenues From Operations [Member]
Schedule of Equity Method Investments [Line Items]
Income (loss) from equity method investments	20,000,000	30,000,000	$ 30,000,000
Bayview Lending Group and Bayview Financial [Member]
Schedule of Equity Method Investments [Line Items]
Outstanding principal balances of mortgage servicing rights	1,200,000,000	1,400,000,000
Revenue from contract with customer	6,000,000	8,000,000	9,000,000
Bayview Financial [Member]
Schedule of Equity Method Investments [Line Items]
Outstanding principal balances of residential mortgage loans from Bayview Financial	115,300,000,000	96,000,000,000
Revenues from sub-servicing	125,000,000	154,000,000	153,000,000
Investment securities in held-to-maturity portfolio securitized by Bayview Financial	42,000,000	$ 50,000,000
FHA gauranteed purchase amount of deliquent loan			1,000,000,000
Bayview Financial [Member] \| FHA Guaranteed Mortgage Loans [Member]
Schedule of Equity Method Investments [Line Items]
FHA gauranteed mortgage loan			$ 965,000,000
Bayview Financial [Member] \| Syndicated Loan Facility [Member]
Schedule of Equity Method Investments [Line Items]
Loan facility carrying amount	3,200,000,000
Bayview Financial [Member] \| Syndicated Loan Facility [Member] \| M&T Bank [Member]
Schedule of Equity Method Investments [Line Items]
Loan facility carrying amount	$ 672,000,000

Segment Information - Information about Company's Segments (Parenthetical) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Segment Reporting Information [Line Items]
Taxable-equivalent adjustment	$ 54	$ 39	$ 15

Pension plans and other postretirement benefits

12 Months Ended

Dec. 31, 2023

Retirement Benefits [Abstract]

Pension plans and other postretirement benefits

13. Pension plans and other postretirement benefits

The Company provides defined pension and other postretirement benefits (including health care and life insurance benefits) to qualified retired employees. The Company uses a December 31 measurement date for all of its plans.

Net periodic pension expense for defined benefit plans consisted of the following:


	Year Ended December 31,
(Dollars in millions)	2023			2022			2021
Service cost	$	11		$	18		$	20
Interest cost on benefit obligation		115			82			62
Expected return on plan assets		(201	)		(188	)		(143	)
Amortization of prior service cost		—			1			1
Recognized net actuarial (gain) loss		(2	)		20			89
Net periodic pension (benefit) cost	$	(77	)	$	(67	)	$	29

Net other postretirement benefits expense for defined benefit plans consisted of the following:


	Year Ended December 31,
(Dollars in millions)	2023			2022			2021
Service cost	$	2		$	3		$	1
Interest cost on benefit obligation		3			2			1
Amortization of prior service credit		(2	)		(3	)		(5	)
Recognized net actuarial gain		(3	)		(1	)		(1	)
Net other postretirement (benefit) cost	$	—		$	1		$	(4	)

Service cost is reflected in salaries and employee benefits expense. The other components of net periodic benefit costs are reflected in other costs of operations.

Prior to 2022, net actuarial losses were generally amortized over the average remaining service periods of active participants in the Company’s qualified defined benefit pension plan. If all or substantially all of the plan’s participants are inactive, GAAP provides for the average remaining life expectancy of the participants to be used instead of average remaining service period in determining such amortization. Substantially all of the participants in the Company’s qualified defined benefit pension plan were inactive and beginning in 2022 the average remaining life expectancy is now utilized prospectively to amortize the net unrecognized losses. The change increased the amortization period by approximately sixteen years and reduced the amount of amortization of unrecognized losses recorded for the year ended December 31, 2022 from what would have been recorded without such change in amortization period by $36 million.

Data relating to the funding position of the defined benefit plans were as follows:


	Pension Benefits						Other Postretirement Benefits
(Dollars in millions)	2023			2022			2023			2022
Change in benefit obligation:
Benefit obligation at beginning of year	$	2,379		$	2,420		$	60		$	52
Service cost		11			18			2			3
Interest cost		115			82			3			2
Plan participants’ contributions		—			—			1			2
Actuarial (gain) loss		13			(636	)		(5	)		(22	)
Plan amendment		—			—			—			13
Business combinations		—			633			—			15
Medicare Part D reimbursement		—			—			—			1
Benefits paid		(149	)		(138	)		(4	)		(6	)
Benefit obligation at end of year		2,369			2,379			57			60
Change in plan assets:
Fair value of plan assets at beginning of year		2,942			2,596			—			—
Actual return on plan assets		334			(386	)		—			—
Employer contributions		18			14			3			3
Business combinations		—			856			—			—
Plan participants’ contributions		—			—			1			2
Medicare Part D reimbursement		—			—			—			1
Benefits paid		(149	)		(138	)		(4	)		(6	)
Fair value of plan assets at end of year		3,145			2,942			—			—
Funded status	$	776		$	563		$	(57	)	$	(60	)
Prepaid asset recognized in the Consolidated Balance Sheet	$	922		$	715		$	—		$	—
Accrued liability recognized in the Consolidated Balance Sheet		(146	)		(152	)		(57	)		(60	)
Net accrued asset (liability) recognized in the Consolidated Balance Sheet	$	776		$	563		$	(57	)	$	(60	)
Amounts recognized in accumulated other comprehensive income were:
Net loss (gain)	$	191		$	309		$	(37	)	$	(35	)
Net prior service cost (credit)		—			—			1			(1	)
Pre-tax adjustment to accumulated other comprehensive income		191			309			(36	)		(36	)
Taxes		(49	)		(80	)		9			9
Net adjustment to accumulated other comprehensive income	$	142		$	229		$	(27	)	$	(27	)

The Company has an unfunded supplemental pension plan for certain key executives and others. The projected benefit obligation and accumulated benefit obligation included in the preceding data related to such plan were $146 million as of December 31, 2023 and $152 million as of December 31, 2022. The accumulated benefit obligation for all defined benefit pension plans was $2.4 billion at each of December 31, 2023 and 2022.

GAAP requires an employer to recognize in its balance sheet as an asset or liability the overfunded or underfunded status of a defined benefit postretirement plan, measured as the difference between the fair value of plan assets and the benefit obligation. For a pension plan, the benefit obligation is the projected benefit obligation; for any other postretirement benefit plan, such as a retiree health care plan, the benefit obligation is the accumulated postretirement benefit obligation. Gains or losses and prior service costs or credits that arise during the period, but are not included as components of net periodic benefit expense, are recognized as a component of other comprehensive income. Amortization of net gains and losses is included in annual net periodic benefit expense if, as of the beginning of the year, the net gain or loss exceeds 10% of the greater of the benefit obligation or the market-related fair value of the plan assets. As indicated in the preceding table, as of December 31, 2023 the Company recorded a minimum liability adjustment of $155 million ($191 million related to pension plans and ($36 million) related to other postretirement benefits) with a corresponding reduction of shareholders’ equity, net of applicable deferred taxes, of $115 million. In aggregate, the benefit plans realized a net gain during 2023 that resulted in a decrease to the minimum liability adjustment from that which was recorded at December 31, 2022 of $118 million. The net gain in 2023 was mainly the result of a return on plan assets that was greater than the assumed expected return. The table below reflects the changes in plan assets and benefit obligations recognized in other comprehensive income related to the Company’s postretirement benefit plans.


(Dollars in millions)	Pension Plans			Other Postretirement Benefit Plans			Total
2023
Net gain	$	(120	)	$	(5	)	$	(125	)
Amortization of prior service credit		—			2			2
Amortization of actuarial gain		2			3			5
Total recognized in other comprehensive income, pre-tax	$	(118	)	$	—		$	(118	)
2022
Net gain	$	(62	)	$	(22	)	$	(84	)
Net prior service cost		—			13			13
Amortization of prior service (cost) credit		(1	)		3			2
Amortization of actuarial (loss) gain		(20	)		2			(18	)
Total recognized in other comprehensive income, pre-tax	$	(83	)	$	(4	)	$	(87	)

Assumptions

The assumed weighted-average rates used to determine benefit obligations at December 31 were:


	Pension Benefits						Other Postretirement Benefits
	2023			2022			2023			2022
Discount rate		5.00	%		5.00	%		5.00	%		5.00	%
Rate of increase in future compensation levels		3.32			3.33			—			—

The assumed weighted-average rates used to determine net benefit expense for the years ended December 31 were:


	Pension Benefits									Other Postretirement Benefits
	2023			2022			2021			2023			2022			2021
Discount rate		5.00	%		2.75	%		2.50	%		5.00	%		2.75	%		2.50	%
Long-term rate of return on plan assets		6.25			6.25			6.25			—			—			—
Rate of increase in future compensation levels		3.33			3.35			3.37			—			—			—

The discount rate used by the Company to determine the present value of the Company’s future benefit obligations reflects specific market yields for a hypothetical portfolio of highly rated corporate bonds that would produce cash flows similar to the Company’s benefit plan obligations and the level of market interest rates in general as of the year-end.

The expected long-term rate of return assumption as of each measurement date was developed through analysis of historical market returns, current market conditions, anticipated future asset allocations, the funds’ past experience, and expectations on potential future market returns. The expected rate of return assumption represents a long-term average view of the performance of the plan assets, a return that may or may not be achieved during any one calendar year.

The Company’s defined benefit pension plan is sensitive to the long-term rate of return on plan assets and the discount rate. To demonstrate the sensitivity of the net periodic pension benefit for 2023 to changes in these assumptions, with all other assumptions held constant, 25 basis point increases in: the rate of return on plan assets would have resulted in an increase in pension benefit of approximately $8 million; and the discount rate would have resulted in a decrease in pension benefit of approximately $1 million. Decreases of 25 basis points in those assumptions would have resulted in similar changes in amount, but in the opposite direction from the changes presented in the preceding sentence. Additionally, an increase of 25 basis points in the discount rate would have decreased the benefit obligation by $62 million and a decrease of 25 basis points in the discount rate would have increased the benefit obligation by $65 million at December 31, 2023.

For measurement of other postretirement benefits, a 6.75% annual rate of increase in the per capita cost of covered health care benefits was assumed for 2023. The rate was assumed to decrease to 5.00% over seven years.

Plan assets

The Company’s policy is to invest the pension plan assets in a prudent manner for the purpose of providing benefit payments to participants and mitigating reasonable expenses of administration. The Company’s investment strategy is designed to provide a total return that, over the long-term, places an emphasis on the preservation of capital. The strategy attempts to maximize investment returns on assets at a level of risk deemed appropriate by the Company while complying with applicable regulations and laws. The investment strategy utilizes asset diversification as a principal determinant for establishing an appropriate risk profile while emphasizing total return realized from capital appreciation, dividends and interest income. The target allocations for plan assets are generally 25 to 60 percent equity securities, 10 to 65 percent debt securities, and 5 to 60 percent money-market investments/cash equivalents and other investments, although holdings could be more or less than these general guidelines based on market conditions at the time and actions taken or recommended by the investment managers providing advice to the Company. Assets are managed by a combination of internal and external investment managers. Equity securities may include investments in domestic and international equities through individual securities, mutual funds and exchange-traded funds. Debt securities may include investments in corporate bonds of companies from diversified industries, mortgage-backed securities guaranteed by government agencies and U.S. Treasury securities through individual securities and mutual funds. Additionally, the Company’s defined benefit pension plan held $668 million (21% of total assets) of real estate funds, private investments, hedge funds and other investments at December 31, 2023. No investment in securities of a non-U.S. Government or government agency issuer exceeded ten percent of plan assets at December 31, 2023. Returns on invested assets are periodically compared with target market indices for each asset type to aid management in evaluating such returns. Furthermore, management regularly reviews the investment policy and may, if deemed appropriate, make changes to the target allocations noted above.

The fair values of the Company’s pension plan assets at December 31, 2023 and 2022, by asset category, were as follows:


	Fair Value Measurement of Plan Assets At December 31, 2023
(Dollars in millions)	Total		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Asset category:
Money-market investments	$	65	$	41	$	24	$	—
Equity securities:
M&T		112		112		—		—
Domestic (a)		512		512		—		—
International (b)		17		17		—		—
Mutual funds:
Domestic (a)		307		307		—		—
International (b)		501		501		—		—
		1,449		1,449		—		—
Debt securities:
Corporate (c)		227		—		227		—
Government		276		—		276		—
International		6		—		6		—
Mutual funds:
Domestic (d)		450		450		—		—
		959		450		509		—
Other:
Diversified mutual fund		110		110		—		—
Real estate partnerships		29		7		—		22
Private equity / debt		235		—		—		235
Hedge funds		285		107		—		178
Guaranteed deposit fund		9		—		—		9
		668		224		—		444
Total (e)	$	3,141	$	2,164	$	533	$	444


	Fair Value Measurement of Plan Assets At December 31, 2022
(Dollars in millions)	Total		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Asset category:
Money-market investments	$	90	$	52	$	38	$	—
Equity securities:
M&T		118		118		—		—
Domestic (a)		450		450		—		—
International (b)		19		19		—		—
Mutual funds:
Domestic (a)		279		279		—		—
International (b)		477		477		—		—
		1,343		1,343		—		—
Debt securities:
Corporate (c)		200		—		200		—
Government		236		—		236		—
International		15		—		15		—
Mutual funds:
Domestic (d)		422		422		—		—
		873		422		451		—
Other:
Diversified mutual fund		108		108		—		—
Real estate partnerships		27		7		—		20
Private equity / debt		211		—		—		211
Hedge funds		276		109		—		167
Guaranteed deposit fund		10		—		—		10
		632		224		—		408
Total (e)	$	2,938	$	2,041	$	489	$	408

(a)

This category is mainly comprised of equities of companies primarily within the small-cap, mid-cap and large-cap sectors of the U.S. economy and range across diverse industries.

(b)

This category is comprised of equities in companies primarily within the mid-cap and large-cap sectors of international markets mainly in developed and emerging markets in Europe and the Pacific Rim.

(c)

This category represents investment grade bonds of U.S. issuers from diverse industries.

(d)

(e)

Excludes dividends and interest receivable totaling $4 million at each of December 31, 2023 and 2022.

The changes in Level 3 pension plan assets measured at estimated fair value on a recurring basis during the year ended December 31, 2023 were as follows:


(Dollars in millions)	Balance – January 1, 2023		Net Purchases (Sales)		Realized/ Unrealized Gains (Losses)			Balance – December 31, 2023
Real estate partnerships	$	20	$	2	$	—		$	22
Private equity/debt		211		12		12			235
Hedge funds		167		—		11			178
Guaranteed deposit fund		10		—		(1	)		9
Total	$	408	$	14	$	22		$	444

The Company makes contributions to its funded qualified defined benefit pension plan as required by government regulation or as deemed appropriate by management after considering factors such as the fair value of plan assets, expected returns on such assets and the present value of benefit obligations of the plan. The Company is not required to make contributions to the qualified defined benefit plan in 2024, however, subject to the impact of actual events and circumstances that may occur in 2024, the Company may make contributions, but the amount of any such contributions has not been determined. The Company regularly funds the payment of benefit obligations for the supplemental defined benefit pension and postretirement benefit plans because such plans do not hold assets for investment. Payments made by the Company for supplemental pension benefits were $18 million and $14 million in 2023 and 2022, respectively. Payments made by the Company for postretirement benefits were $3 million in each of 2023 and 2022. Payments for supplemental pension and other postretirement benefits for 2024 are not expected to differ from those made in 2023 by an amount that will be material to the Company’s consolidated financial position.

Estimated benefits expected to be paid in future years related to the Company’s defined benefit pension and other postretirement benefits plans are as follows:


(Dollars in millions)	Pension Benefits		Other Postretirement Benefits
Year ending December 31:
2024	$	150	$	4
2025		154		4
2026		157		4
2027		160		4
2028		164		4
2029 through 2033		838		19

The Company also provides a qualified defined contribution pension plan to eligible employees who were not participants in the defined benefit pension plan as of December 31, 2005 and to other employees who have elected to participate in the defined contribution plan. The Company makes contributions to the defined contribution plan each year in an amount that is based on an individual participant’s total compensation (generally defined as total wages, incentive compensation, commissions and bonuses) and years of service. Company contributions to the plan are discretionary for participants for which eligibility occurred after January 1, 2020. Participants do not contribute to the defined contribution pension plan. Pension expense recorded in 2023, 2022 and 2021 associated with the defined contribution pension plan was $56 million, $45 million and $40 million, respectively.

The Company has a retirement savings plan that is a defined contribution plan in which eligible employees of the Company may defer up to 50% of qualified compensation via contributions to the plan. The retirement savings plan provides for employer matching contributions of 100% of an employee's qualified compensation up to 5%. Employees’ accounts, including employee contributions, employer matching contributions and accumulated earnings thereon, are at all times fully vested and

nonforfeitable. Employee benefits expense resulting from the Company’s contributions to the retirement savings plan totaled $96 million, $84 million and $63 million in 2023, 2022 and 2021, respectively.

- Definition

The entire disclosure for retirement benefits.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 70
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480794/715-70-50-1

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 17
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480482/715-20-55-17

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (d)(iv)(03)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (d)(i)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (q)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (l)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org//715/tableOfContent

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (d)(iii)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (o)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (p)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (r)(1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (r)(2)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480126/715-20-S99-2

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 60
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480266/715-60-50-3

+ Details

Derivative Financial Instruments - Information about Interest Rate Swap Agreements (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Derivative [Line Items]
Notional Amount	$ 26,977	$ 17,400
Average Maturity (in years)	2 years 2 months 12 days	1 year 7 months 6 days
Estimated Fair Value Gain (Loss)	$ 10	$ (8)
Interest Payments On Variable Rate Commercial Real Estate Loans [Member] \| Cash Flow Hedges [Member]
Derivative [Line Items]
Notional Amount	$ 23,977	$ 15,900
Average Maturity (in years)	1 year 8 months 12 days	1 year 4 months 24 days
Weighted-Average Rate, Fixed	3.45%	1.91%
Weighted-Average Rate, Variable	5.36%	4.38%
Estimated Fair Value Gain (Loss)	$ 11	$ (7)
Fixed Rate Long-Term Borrowings [Member] \| Fair Value Hedges [Member]
Derivative [Line Items]
Notional Amount	$ 3,000	$ 1,500
Average Maturity (in years)	5 years 9 months 18 days	3 years 3 months 18 days
Weighted-Average Rate, Fixed	3.45%	2.98%
Weighted-Average Rate, Variable	5.62%	4.52%
Estimated Fair Value Gain (Loss)	$ (1)	$ (1)

Loans and Leases - Total Loans and Leases Outstanding (Detail) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Loans
Total loans	$ 132,122	$ 129,492
Leases
Total loans and leases	134,936	132,074
Unearned discount	(868)	(510)
Loans and leases, net of unearned discount	134,068	131,564
Commercial and Industrial [Member]
Loans
Total loans	55,000	49,775
Commercial Real Estate [Member]
Loans
Total loans	33,065	35,364
Residential Real Estate [Member]
Loans
Total loans	23,277	23,774
Consumer Real Estate [Member]
Loans
Total loans	20,780	20,579
Commercial Lease [Member]
Loans
Total loans	$ 2,814	$ 2,582

Pension Plans and Other Postretirement Benefits - Assumed Weighted-Average Rates Used to Determine Benefit Obligations (Detail)	Dec. 31, 2023	Dec. 31, 2022
Pension Benefits [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Discount rate	5.00%	5.00%
Rate of increase in future compensation levels	3.32%	3.33%
Other Postretirement Benefits [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Discount rate	5.00%	5.00%

Premises and equipment

12 Months Ended

Dec. 31, 2023

Property, Plant and Equipment [Abstract]

Premises and equipment

6. Premises and equipment

The detail of premises and equipment was as follows:


	December 31,
(Dollars in millions)	2023		2022
Land	$	148	$	149
Buildings		685		654
Leasehold improvements		413		387
Furniture and equipment		1,097		1,004
		2,343		2,194
Less: accumulated depreciation and amortization		1,220		1,156
Right-of-use assets — operating leases		616		616
Premises and equipment, net	$	1,739	$	1,654

The right-of-use assets and lease liabilities relate to banking offices and other space occupied by the Company and use of certain equipment under noncancelable operating lease agreements. As of December 31, 2023 and 2022, the Company recognized $717 million and $709 million respectively, of operating lease liabilities as a component of “accrued interest and other liabilities” in the Consolidated Balance Sheet. In calculating the present value of lease payments, the Company utilized its incremental secured borrowing rate based on lease term.

The Company’s noncancelable operating lease agreements expire at various dates over the next 18 years. Real estate leases generally consist of fixed monthly rental payments with certain leases containing escalation clauses. Any variable lease payments or payments for nonlease components are recognized in the Consolidated Statement of Income as a component of “equipment and net occupancy” expense based on actual costs incurred. Some leases contain lessee options to extend the term. Those options are included in the lease term when it is determined that it is reasonably certain the option will be exercised.

The Company has noncancelable operating lease agreements for certain equipment related to ATMs, servers, printers and mail machines that are used in the normal course of operations. The ATM leases are either based on the rights to a specific square footage or a license agreement whereby the Company has the right to operate an ATM in a landlord's location. The lease terms generally contain both fixed payments and variable payments that are transaction-based. Given the transaction-based nature of the variable payments, such payments are excluded from the measurement of the right-of-use asset and lease liability and are recognized in the Consolidated Statement of Income as a component of “equipment and net occupancy” expense when incurred.

The following table presents information about the Company’s lease costs for operating leases recorded in the Consolidated Balance Sheet, cash paid toward lease liabilities, and the weighted-average remaining term and discount rates of the operating leases.


	Year Ended December 31,
(Dollars in millions)	2023			2022			2021
Lease cost
Operating lease cost	$	154		$	139		$	102
Short-term lease cost		—			8			—
Variable lease cost		4			4			4
Total lease cost	$	158		$	151		$	106

Other information
Right-of-use assets:
Obtained in exchange for new operating lease liabilities	$	134		$	138		$	58
Acquired in business combination		—			226			—
Cash paid toward lease liabilities		158			143			107
Weighted-average remaining lease term	7 years			7 years			6 years
Weighted-average discount rate		3.37	%		2.97	%		2.51	%

Minimum lease payments under noncancelable operating leases are summarized in the following table.


(Dollars in millions)
Year ending December 31:
2024	$	162
2025		145
2026		122
2027		101
2028		75
Later years		208
Total lease payments		813
Less: imputed interest		96
Total	$	717

All other operating leasing activities were not material to the Company’s consolidated results of operations. Minimum lease payments required under finance leases are not material.

Loans and Leases (Tables)

12 Months Ended

Dec. 31, 2023

Receivables [Abstract]

Total Loans and Leases Outstanding

Total loans and leases outstanding were comprised of the following:


	December 31,
(Dollars in millions)	2023			2022
Loans:
Commercial and industrial	$	55,000		$	49,775
Commercial real estate		33,065			35,364
Residential real estate		23,277			23,774
Consumer		20,780			20,579
Total loans		132,122			129,492
Leases:
Commercial		2,814			2,582
Total loans and leases		134,936			132,074
Less: unearned discount		(868	)		(510	)
Total loans and leases, net of unearned discount	$	134,068		$	131,564

Summary of Current, Past Due and Nonaccrual Loans

A summary of current, past due and nonaccrual loans as of December 31, 2023 and 2022 follows:


(Dollars in millions)	Current		30-89 Days Past Due		Accruing Loans Past Due 90 Days or More		Nonaccrual		Total
December 31, 2023
Commercial and industrial	$	56,091	$	238	$	11	$	670	$	57,010
Real estate:
Commercial		24,072		311		25		869		25,277
Residential builder and developer		1,065		5		—		3		1,073
Other commercial construction		6,322		159		1		171		6,653
Residential		21,080		763		295		215		22,353
Residential — limited documentation		825		31		—		55		911
Consumer:
Home equity lines and loans		4,528		40		—		81		4,649
Recreational finance		9,935		87		—		36		10,058
Automobile		3,918		60		—		14		3,992
Other		2,003		30		7		52		2,092
Total	$	129,839	$	1,724	$	339	$	2,166	$	134,068

December 31, 2022
Commercial and industrial	$	50,842	$	498	$	76	$	504	$	51,920
Real estate:
Commercial		25,113		261		65		1,240		26,679
Residential builder and developer		1,305		9		—		1		1,315
Other commercial construction		6,937		240		—		125		7,302
Residential		21,492		596		345		272		22,705
Residential — limited documentation		951		22		—		78		1,051
Consumer:
Home equity lines and loans		4,891		31		—		85		5,007
Recreational finance		8,974		55		—		45		9,074
Automobile		4,393		44		—		40		4,477
Other		1,957		23		5		49		2,034
Total	$	126,855	$	1,779	$	491	$	2,439	$	131,564

Loan Modification Activities to Borrowers Experiencing Financial Difficulty on Financing Receivables

The table that follows summarizes the Company’s loan modification activities to borrowers experiencing financial difficulty for the year ended December 31, 2023:


	Amortized cost at December 31, 2023
(Dollars in millions)	Payment Deferral		Interest Rate Reduction		Other		Combination of Modification Types (a)		Total (b) (c)		Percent of Total Loan Class
Year Ended December 31, 2023
Commercial and industrial	$	179	$	18	$	—	$	1	$	198		.35	%
Real estate:
Commercial		610		—		—		41		651	2.57
Residential builder and developer		71		—		—		—		71	6.63
Other commercial construction		480		—		—		8		488	7.34
Residential		160		—		—		5		165		.74
Residential — limited documentation		11		—		—		1		12	1.25
Consumer:
Home equity lines and loans		—		—		—		1		1		.03
Recreational finance		—		—		—		—		—		—
Automobile		—		—		—		—		—		—
Other		—		—		—		—		—		—
Total	$	1,511	$	18	$	—	$	57	$	1,586		1.18	%

(a)

Predominantly payment deferrals combined with interest rate reductions.

(b)

Includes approximately $124 million of loans guaranteed by government-related entities (predominantly first lien residential mortgage loans).

(c)

Excludes unfunded commitments to extend credit totaling $128 million.

Summary of Payment Status of Loans Modified

The following table summarizes the payment status, at December 31, 2023, of loans that were modified during 2023.


	Payment status at December 31, 2023 (amortized cost)
(Dollars in millions)	Current		30-89 Days Past Due		Past Due 90 Days or More (a)		Total
Year Ended December 31, 2023
Commercial and industrial	$	182	$	7	$	9	$	198
Real estate:
Commercial		618		21		12		651
Residential builder and developer		71		—		—		71
Other commercial construction		440		48		—		488
Residential (b)		93		45		27		165
Residential — limited documentation		9		2		1		12
Consumer:
Home equity lines and loans		1		—		—		1
Recreational finance		—		—		—		—
Automobile		—		—		—		—
Other		—		—		—		—
Total	$	1,414	$	123	$	49	$	1,586

(a)

Predominantly loan modifications with payment deferrals.

(b)

Includes loans guaranteed by government-related entities classified as 30-89 days past due of $40 million and as past due 90 days or more of $24 million.

Loan Modification Activities that were Considered Troubled Debt Restructurings

The table that follows summarizes the Company’s loan modification activities that were considered troubled debt restructurings for the years ended December 31, 2022 and 2021.


					Post-modification (a)
(Dollars in millions)	Number		Pre- modification Recorded Investment		Principal Deferral		Interest Rate Reduction		Other		Combination of Concession Types		Total
Year Ended December 31, 2022
Commercial and industrial		231	$	98	$	58	$	—	$	3	$	37	$	98
Real estate:
Commercial		12		25		9		—		—		16		25
Residential builder and developer		1		—		—		—		—		—		—
Other commercial construction		1		—		—		—		—		—		—
Residential		274		71		55		—		—		20		75
Residential — limited documentation		8		1		1		—		—		—		1
Consumer:
Home equity lines and loans		144		10		9		—		—		1		10
Recreational finance		729		28		28		—		—		—		28
Automobile		2,092		42		42		—		—		—		42
Other		149		1		1		—		—		—		1
Total		3,641	$	276	$	203	$	—	$	3	$	74	$	280

Year Ended December 31, 2021
Commercial and industrial		348	$	205	$	58	$	—	$	45	$	99	$	202
Real estate:
Commercial		35		184		57		—		27		98		182
Residential builder and developer		1		—		—		—		—		—		—
Other commercial construction		3		—		—		—		—		—		—
Residential		373		108		95		—		—		13		108
Residential — limited documentation		21		3		3		—		—		—		3
Consumer:
Home equity lines and loans		89		6		6		—		—		—		6
Recreational finance		281		10		10		—		—		—		10
Automobile		807		15		15		—		—		—		15
Other		362		3		3		—		—		—		3
Total		2,320	$	534	$	247	$	—	$	72	$	210	$	529

(a)

Financial effects impacting the recorded investment included principal payments or advances, charge-offs and capitalized escrow arrearages. The present value of interest rate concessions, discounted at the effective rate of the original loan, was not material.

Summary of Lease Financing Receivables

A summary of lease financing receivables follows.


	December 31,
(Dollars in millions)	2023			2022
Commercial leases:
Financing:
Lease payments receivable	$	2,431		$	2,175
Estimated residual value of leased assets		274			262
Unearned income		(248	)		(145	)
Investment in financing leases		2,457			2,292
Leveraged:
Lease payments receivable		57			71
Estimated residual value of leased assets		52			74
Unearned income		(15	)		(22	)
Investment in leveraged leases		94			123
Total investment in leases	$	2,551		$	2,415
Deferred taxes payable arising from leveraged leases	$	36		$	52

Minimum Future Lease Payments to be Received from Lease Financings

At December 31, 2023, the minimum future lease payments to be received from lease financings were as follows:


(Dollars in millions)
Year ending December 31:
2024	$	823
2025		677
2026		468
2027		290
2028		136
Later years		94
	$	2,488

Consolidated Statement of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Cash flows from operating activities
Net Income (Loss)	$ 2,741	$ 1,992	$ 1,859
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for credit losses	645	517	(75)
Depreciation and amortization of premises and equipment	304	282	224
Amortization of capitalized servicing rights	131	97	90
Amortization of core deposit and other intangible assets	62	56	10
Provision for deferred income taxes	(97)	(30)	87
Asset write-downs	4	8	8
Net gain on sales of assets	(249)	(153)	(10)
Net change in accrued interest receivable, payable	261	(123)	66
Net change in other accrued income and expense	561	(70)	53
Net change in loans originated for sale	(192)	771	(164)
Net change in trading account and other non-hedging derivative assets and liabilities	(266)	1,227	567
Net cash provided by operating activities	3,905	4,574	2,715
Cash flows from investing activities
Proceeds from sales of investment securities equity and other	1,014	242	18
Proceeds from maturities of investment securities Available for sale	743	795	1,434
Proceeds from maturities of investment securities Held to maturity	1,170	1,516	615
Purchases of investment securities Available for sale	(346)	(7,222)	(678)
Purchases of investment securities Held to maturity	(2,948)	(1,890)	(1,602)
Purchases of investment securities equity and other	(1,205)	(456)	(30)
Net (increase) decrease in loans and leases	(2,770)	(3,639)	5,677
Net (increase) decrease in interest-bearing deposits at banks	(3,110)	26,107	(18,208)
Capital expenditures, net	(256)	(214)	(149)
Net (increase) decrease in loan servicing advances	274	1,579	(197)
Acquisition, net of cash consideration, Bank and bank holding company		394
Other, net	(440)	(620)	(511)
Net cash provided (used) by investing activities	(7,874)	16,592	(13,631)
Cash flows from financing activities
Net increase (decrease) in deposits	(248)	(20,994)	11,738
Net increase (decrease) in short-term borrowings	1,761	2,613	(13)
Proceeds from long-term borrowings	5,035	999	10
Payments on long-term borrowings	(824)	(907)	(853)
Purchases of treasury stock	(594)	(1,800)
Dividends paid — common	(868)	(784)	(580)
Dividends paid — preferred	(100)	(97)	(68)
Proceeds from issuance of Series I preferred stock			495
Other, net	18	(14)	(28)
Net cash provided (used) by financing activities	4,180	(20,984)	10,701
Net increase (decrease) in cash, cash equivalents and restricted cash	211	182	(215)
Cash, cash equivalents and restricted cash at beginning of period	1,520	1,338	1,553
Cash, cash equivalents and restricted cash at end of period	1,731	1,520	1,338
Supplemental disclosure of cash flow information
Interest received during the period	10,092	6,135	3,977
Interest paid during the period	2,691	429	139
Income taxes paid during the period	452	488	314
Supplemental schedule of noncash investing and financing activities
Real estate acquired in settlement of loans	23	31	9
Additions to right-of-use assets under operating leases	$ 134	138	58
Loans held for sale transferred to loans held for investment			$ 330
Acquisition of bank and bank holding company, Common stock issued		8,286
Acquisition of bank and bank holding company, Common stock awards converted		105
Fair value of Assets acquired (noncash)		63,757
Fair value of Liabilities assumed		55,499
Fair value of Preferred stock converted		$ 261

Consolidated Statement of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Statement of Partners' Capital [Abstract]
Net Income (Loss)	$ 2,741	$ 1,992	$ 1,859
Other comprehensive income (loss), net of tax and reclassification adjustments:
Net unrealized gains (losses) on investment securities	142	(407)	(67)
Cash flow hedges adjustments	98	(315)	(211)
Defined benefit plans liability adjustments	87	65	214
Foreign currency translation adjustments	4	(6)	(1)
Total other comprehensive income (loss)	331	(663)	(65)
Total comprehensive income	$ 3,072	$ 1,329	$ 1,794

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

+ Details

- Definition

Amount after tax and reclassification adjustments of other comprehensive income (loss).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-SubTopic 10
-Topic 505
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-2

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 830
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481674/830-30-50-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 830
-SubTopic 30
-Name Accounting Standards Codification
-Section 45
-Paragraph 17
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481694/830-30-45-17

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(19))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483586/944-220-S99-1

Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482765/220-10-50-4

Reference 6: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482765/220-10-50-5

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 830
-SubTopic 30
-Name Accounting Standards Codification
-Section 45
-Paragraph 20
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481694/830-30-45-20

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(21))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483621/220-10-S99-2

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(23))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483589/942-220-S99-1

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 1B
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482790/220-10-45-1B

Reference 11: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 55
-Paragraph 15
-SubTopic 10
-Topic 220
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482739/220-10-55-15

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 1A
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482790/220-10-45-1A

+ Details

Income Taxes - Deferred Tax Assets (Liabilities) (Detail) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Losses on loans and other assets	$ 686	$ 641	$ 396
Operating lease liabilities	182	183	110
Postretirement and other employee benefits	47		32
Incentive and other compensation plans	30	34	25
Unrealized losses	64	115
Interest on loans	42	54
Losses on cash flow hedges	52	87
Stock-based compensation	54	51	33
Other	153	81	52
Gross deferred tax assets	1,310	1,246	648
Right-of-use assets and other leasing transactions	(336)	(367)	(249)
Unrealized gains			(27)
Retirement benefits	(198)	(88)	(46)
Capitalized servicing rights	(38)	(51)	(53)
Postretirement and other employee benefits		(29)
Depreciation and amortization	(157)	(155)	(93)
Interest on loans			(7)
Gains on cash flow hedges			(23)
Other	(59)	(69)	(88)
Gross deferred tax liabilities	(788)	(759)	(586)
Net deferred tax asset	$ 522	$ 487	$ 62

Comprehensive income (Tables)

12 Months Ended

Dec. 31, 2023

Equity [Abstract]

Components of Other Comprehensive Income (Loss) and Amounts Reclassified from Accumulated Other Comprehensive Income (Loss) to Net Income

The following tables display the components of other comprehensive income (loss) and amounts reclassified from accumulated other comprehensive income (loss) to net income:


	Investment			Defined Benefit			Cash Flow Hedges and			Total Amount				Income
(Dollars in millions)	Securities			Plans			Other			Before Tax				Tax			Net
Balance — January 1, 2023	$	(444	)	$	(273	)	$	(349	)	$	(1,066	)		$	276		$	(790	)
Other comprehensive income before reclassifications:
Unrealized holding gains, net		193			—			—			193				(51	)		142
Foreign currency translation adjustment		—			—			5			5				(1	)		4
Unrealized losses on cash flow hedges		—			—			(116	)		(116	)			30			(86	)
Current year benefit plans gains		—			125			—			125				(33	)		92
Total other comprehensive income (loss) before reclassifications		193			125			(111	)		207				(55	)		152
Amounts reclassified from accumulated other comprehensive income that (increase) decrease net income:
Net yield adjustment from cash flow hedges currently in effect		—			—			250			250		(a)		(66	)		184
Amortization of prior service credit		—			(2	)		—			(2	)	(b)		1			(1	)
Amortization of actuarial gains		—			(5	)		—			(5	)	(b)		1			(4	)
Total other comprehensive income (loss)		193			118			139			450				(119	)		331
Balance — December 31, 2023	$	(251	)	$	(155	)	$	(210	)	$	(616	)		$	157		$	(459	)

Balance — January 1, 2022	$	105		$	(360	)	$	84		$	(171	)		$	44		$	(127	)
Other comprehensive income before reclassifications:
Unrealized holding losses, net		(551	)		—			—			(551	)			143			(408	)
Foreign currency translation adjustment		—			—			(8	)		(8	)			2			(6	)
Unrealized losses on cash flow hedges		—			—			(461	)		(461	)			119			(342	)
Current year benefit plans gains		—			71			—			71				(18	)		53
Total other comprehensive income (loss) before reclassifications		(551	)		71			(469	)		(949	)			246			(703	)
Amounts reclassified from accumulated other comprehensive income that (increase) decrease net income:
Amortization of unrealized holding losses on held-to-maturity securities		2			—			—			2		(a)		(1	)		1
Net yield adjustment from cash flow hedges currently in effect		—			—			36			36		(a)		(9	)		27
Amortization of prior service credit		—			(2	)		—			(2	)	(b)		—			(2	)
Amortization of actuarial losses		—			18			—			18		(b)		(4	)		14
Total other comprehensive income (loss)		(549	)		87			(433	)		(895	)			232			(663	)
Balance — December 31, 2022	$	(444	)	$	(273	)	$	(349	)	$	(1,066	)		$	276		$	(790	)


	Investment			Defined Benefit			Cash Flow Hedges and			Total Amount				Income
(Dollars in millions)	Securities			Plans			Other			Before Tax				Tax			Net
Balance — January 1, 2021	$	196		$	(650	)	$	370		$	(84	)		$	22		$	(62	)
Other comprehensive income before reclassifications:
Unrealized holding losses, net		(95	)		—			—			(95	)			25			(70	)
Foreign currency translation adjustment		—			—			(1	)		(1	)			—			(1	)
Unrealized losses on cash flow hedges		—			—			(32	)		(32	)			8			(24	)
Current year benefit plans gains		—			206			—			206				(54	)		152
Total other comprehensive income (loss) before reclassifications		(95	)		206			(33	)		78				(21	)		57
Amounts reclassified from accumulated other comprehensive income that (increase) decrease net income:
Amortization of unrealized holding losses on held-to-maturity securities		4			—			—			4		(a)		(1	)		3
Net yield adjustment from cash flow hedges currently in effect		—			—			(253	)		(253	)	(a)		66			(187	)
Amortization of prior service credit		—			(4	)		—			(4	)	(b)		1			(3	)
Amortization of actuarial losses		—			88			—			88		(b)		(23	)		65
Total other comprehensive income (loss)		(91	)		290			(286	)		(87	)			22			(65	)
Balance — December 31, 2021	$	105		$	(360	)	$	84		$	(171	)		$	44		$	(127	)

(a)

Included in interest income.

(b)

Included in other costs of operations.

Accumulated Other Comprehensive Income (Loss), Net

Accumulated other comprehensive income (loss), net consisted of the following:


(Dollars in millions)	Investment Securities			Defined Benefit Plans			Cash Flow Hedges and Other			Total
Balance at January 1, 2021	$	145		$	(481	)	$	274		$	(62	)
Net gain (loss) during 2021		(67	)		214			(212	)		(65	)
Balance at December 31, 2021		78			(267	)		62			(127	)
Net gain (loss) during 2022		(407	)		65			(321	)		(663	)
Balance at December 31, 2022		(329	)		(202	)		(259	)		(790	)
Net gain during 2023		142			87			102			331
Balance at December 31, 2023	$	(187	)	$	(115	)	$	(157	)	$	(459	)

Comprehensive Income - Accumulated Other Comprehensive Income (Loss), Net (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	$ 25,318	$ 17,903	$ 16,187
Net gain (loss) during period	331	(663)	(65)
Ending balance	26,957	25,318	17,903
Investment Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(329)	78	145
Net gain (loss) during period	142	(407)	(67)
Ending balance	(187)	(329)	78
Defined Benefit Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(202)	(267)	(481)
Net gain (loss) during period	87	65	214
Ending balance	(115)	(202)	(267)
Cash Flow Hedges and Other [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(259)	62	274
Net gain (loss) during period	102	(321)	(212)
Ending balance	(157)	(259)	62
Accumulated Other Comprehensive Income (Loss), Net [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(790)	(127)	(62)
Net gain (loss) during period	331	(663)	(65)
Ending balance	$ (459)	$ (790)	$ (127)

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References + Details

- Definition

Amount after tax and reclassification adjustments of other comprehensive income (loss).

+ References

+ Details

- Definition

Amount of equity (deficit) attributable to parent. Excludes temporary equity and equity attributable to noncontrolling interest.

+ References

+ Details

Consolidated Balance Sheet (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Investment securities, available for sale, amortized cost	$ 10,691	$ 11,193
Investment securities, held to maturity, fair value	14,308	12,375
Equity and other securities, cost	$ 1,125	$ 934
Preferred stock, par value	$ 1.00	$ 1.00
Preferred stock, shares authorized	20,000,000	20,000,000
Preferred stock, shares issued	10,000,000	10,000,000
Preferred stock, liquidation preference per share	$ 25	$ 25
Common stock, par value	$ 0.50	$ 0.50
Common stock, shares authorized	250,000,000	250,000,000
Common stock, shares issued	179,436,779	179,436,779
Common stock issuable, shares	12,217	14,031
Treasury stock, common shares	13,300,298	10,165,419
Series A Series C Series And E Preferred Stock [Member]
Preferred stock, shares issued	350,000	350,000
Preferred stock, shares outstanding	350,000	350,000
Preferred stock, liquidation preference per share	$ 1,000	$ 1,000
Series F And Series G Preferred Stock [Member]
Preferred stock, shares issued	140,000	140,000
Preferred stock, shares outstanding	140,000	140,000
Preferred stock, liquidation preference per share	$ 10,000	$ 10,000

Investment securities

12 Months Ended

Dec. 31, 2023

Investments, Debt and Equity Securities [Abstract]

Investment securities

3. Investment securities

The amortized cost and estimated fair value of investment securities were as follows:


(Dollars in millions)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
December 31, 2023
Investment securities available for sale:
U.S. Treasury and federal agencies	$	7,818	$	—	$	113	$	7,705
Mortgage-backed securities:
Government issued or guaranteed:
Commercial		425		—		9		416
Residential		2,272		—		118		2,154
Other debt securities		176		—		11		165
		10,691		—		251		10,440
Investment securities held to maturity:
U.S. Treasury and federal agencies		1,005		—		31		974
Obligations of states and political subdivisions		2,501		—		67		2,434
Mortgage-backed securities:
Government issued or guaranteed:
Commercial		2,033		—		130		1,903
Residential		9,747		4		802		8,949
Privately issued		42		9		5		46
Other debt securities		2		—		—		2
		15,330		13		1,035		14,308
Total debt securities	$	26,021	$	13	$	1,286	$	24,748
Equity and other securities:
Readily marketable equity — at fair value	$	266	$	5	$	3	$	268
Other — at cost		859		—		—		859
Total equity and other securities	$	1,125	$	5	$	3	$	1,127

December 31, 2022
Investment securities available for sale:
U.S. Treasury and federal agencies	$	7,914	$	—	$	243	$	7,671
Mortgage-backed securities:
Government issued or guaranteed:
Commercial		595		—		21		574
Residential		2,501		—		171		2,330
Other debt securities		183		1		10		174
		11,193		1		445		10,749
Investment securities held to maturity:
U.S. Treasury and federal agencies		1,054		—		46		1,008
Obligations of states and political subdivisions		2,577		—		117		2,460
Mortgage-backed securities:
Government issued or guaranteed:
Commercial		912		—		103		809
Residential		8,935		1		891		8,045
Privately issued		50		9		8		51
Other debt securities		2		—		—		2
		13,530		10		1,165		12,375
Total debt securities	$	24,723	$	11	$	1,610	$	23,124
Equity and other securities:
Readily marketable equity — at fair value	$	153	$	2	$	4	$	151
Other — at cost		781		—		—		781
Total equity and other securities	$	934	$	2	$	4	$	932

No investment in securities of a single non-U.S. Government, government agency or government guaranteed issuer exceeded ten percent of shareholders’ equity at December 31, 2023.

As of December 31, 2023, the latest available investment ratings of all obligations of states and political subdivisions, privately issued mortgage-backed securities and other debt securities were:


					Average Credit Rating of Fair Value Amount
(Dollars in millions)	Amortized Cost		Estimated Fair Value		A or Better		BBB		BB		B or Less		Not Rated
Obligations of states and political subdivisions	$	2,501	$	2,434	$	2,426	$	1	$	—	$	—	$	7
Privately issued mortgage- backed securities		42		46		—		—		—		1		45
Other debt securities		178		167		8		73		31		—		55

There were no significant gross realized gains or losses from sales of investment securities in 2023, 2022 or 2021.

At December 31, 2023, the amortized cost and estimated fair value of debt securities by contractual maturity were as follows:


(Dollars in millions)	Amortized Cost		Estimated Fair Value
Debt securities available for sale:
Due in one year or less	$	5,023	$	4,970
Due after one year through five years		2,921		2,856
Due after five years through ten years		50		44
Due after ten years		—		—
		7,994		7,870
Mortgage-backed securities		2,697		2,570
	$	10,691	$	10,440
Debt securities held to maturity:
Due in one year or less	$	15	$	14
Due after one year through five years		1,179		1,147
Due after five years through ten years		1,351		1,327
Due after ten years		963		922
		3,508		3,410
Mortgage-backed securities		11,822		10,898
	$	15,330	$	14,308


	Less Than 12 Months				12 Months or More
(Dollars in millions)	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
December 31, 2023
Investment securities available for sale:
U.S. Treasury and federal agencies	$	229	$	1	$	7,474	$	112
Mortgage-backed securities:
Government issued or guaranteed:
Commercial		74		1		330		8
Residential		151		2		1,959		116
Other debt securities		6		—		154		11
		460		4		9,917		247
Investment securities held to maturity:
U.S. Treasury and federal agencies		50		—		924		31
Obligations of states and political subdivisions		218		3		2,172		64
Mortgage-backed securities:
Government issued or guaranteed:
Commercial		328		9		1,575		121
Residential		955		11		7,139		791
Privately issued		—		—		34		5
		1,551		23		11,844		1,012
Total	$	2,011	$	27	$	21,761	$	1,259

December 31, 2022
Investment securities available for sale:
U.S. Treasury and federal agencies	$	6,707	$	184	$	842	$	59
Mortgage-backed securities:
Government issued or guaranteed:
Commercial		574		21		—		—
Residential		2,296		169		29		2
Other debt securities		93		4		73		6
		9,670		378		944		67
Investment securities held to maturity:
U.S. Treasury and federal agencies		1,008		46		—		—
Obligations of states and political subdivisions		2,449		117		—		—
Mortgage-backed securities:
Government issued or guaranteed:
Commercial		809		103		—		—
Residential		6,293		619		1,319		272
Privately issued		—		—		36		8
		10,559		885		1,355		280
Total	$	20,229	$	1,263	$	2,299	$	347

The Company owned 4,022 individual debt securities with aggregate gross unrealized losses of $1.3 billion at December 31, 2023. Based on a review of each of the securities in the investment securities portfolio at December 31, 2023, the Company concluded that it expected to recover the amortized cost basis of its investment. As of December 31, 2023, the Company does not intend to sell nor is it anticipated that it would be required to sell any of its impaired investment securities at a loss.

At December 31, 2023, the Company has not identified events or changes in circumstances which may have a significant adverse effect on the fair value of the $859 million of cost method investment securities.

The Company estimated no material allowance for credit losses for its investment securities classified as held-to-maturity at December 31, 2023 or December 31, 2022.

At December 31, 2023 and 2022, investment securities with carrying values of $8.2 billion (including $393 million related to repurchase transactions) and $7.9 billion (including $567 million related to repurchase transactions), respectively, were pledged to secure borrowings, lines of credit and governmental deposits as described in note 9.

Revenue from contracts with customers

12 Months Ended

Dec. 31, 2023

Revenue from Contract with Customer [Abstract]

Revenue from contracts with customers

11. Revenue from contracts with customers

The Company generally charges customer accounts or otherwise bills customers upon completion of its services. Typically the Company’s contracts with customers have a duration of one year or less and payment for services is received at least annually, but oftentimes more frequently as services are provided. At December 31, 2023 and 2022, the Company had $68 million and $74 million, respectively, of amounts receivable related to recognized revenue from the sources in the accompanying tables. Such amounts are classified in “accrued interest and other assets” in the Consolidated Balance Sheet. In certain situations the Company is paid in advance of providing services and defers the recognition of revenue until its service obligation is satisfied. At December 31, 2023 and 2022, the Company had deferred revenue of $54 million and $48 million, respectively, related to the sources in the accompanying tables recorded in “accrued interest and other liabilities” in the Consolidated Balance Sheet. The following tables summarize sources of the Company’s noninterest income during 2023, 2022 and 2021 that are subject to the revenue recognition guidance.


(Dollars in millions)	Commercial Bank		Retail Bank		Institutional Services and Wealth Management		Total
Year Ended December 31, 2023
Classification in Consolidated Statement of Income
Service charges on deposit accounts	$	144	$	330	$	1	$	475
Trust income		2		—		678		680
Brokerage services income		6		—		96		102
Other revenues from operations:
Merchant discount and credit card interchange fees		77		84		—		161
Other		28		30		8		66
	$	257	$	444	$	783	$	1,484

Year Ended December 31, 2022
Classification in Consolidated Statement of Income
Service charges on deposit accounts	$	130	$	317	$	—	$	447
Trust income		—		—		741		741
Brokerage services income		5		—		83		88
Other revenues from operations:
Merchant discount and credit card interchange fees		73		86		—		159
Other		24		28		38		90
	$	232	$	431	$	862	$	1,525

Year Ended December 31, 2021
Classification in Consolidated Statement of Income
Service charges on deposit accounts	$	115	$	287	$	—	$	402
Trust income		—		—		645		645
Brokerage services income		2		—		61		63
Other revenues from operations:
Merchant discount and credit card interchange fees		58		73		—		131
Other		13		30		40		83
	$	188	$	390	$	746	$	1,324

Service charges on deposit accounts include fees deducted directly from customer account balances, such as account maintenance, insufficient funds and other transactional service charges, and also include debit card interchange revenue resulting from customer initiated transactions. Account maintenance charges are generally recognized as revenue on a monthly basis, whereas other fees are recognized after the respective service is provided.

Trust income includes revenues from a variety of trustee, agency, investment, cash management and administrative services, asset management, fiduciary services, and family office services. Trust fees may be billed in arrears or in advance and are recognized as revenue as the Company’s performance obligations are satisfied. Certain fees are based on a percentage of assets invested or under management and are recognized as the service is performed and constraints regarding the uncertainty of the amount of fees are resolved.

Brokerage services income includes revenues from the sale of mutual funds and annuities and securities brokerage fees. Such revenues are generally recognized at the time of transaction execution. Mutual fund and other distribution fees are recognized upon initial placement of customer funds as well as in future periods as such customers continue to hold amounts in those mutual funds.

Other revenues from operations include merchant discount and credit card interchange fees that are generally recognized when the cardholder’s transaction is approved and settled. Also included in other revenues from operations are insurance commissions, ATM surcharge fees, and advisory and other fees. Insurance commissions are recognized at the time the insurance policy is executed with the customer. Insurance renewal commissions are recognized upon subsequent renewal of the policy. ATM surcharge fees are included in revenue at the time of the respective ATM transaction. Advisory and other fees are generally recognized when the Company has satisfied its service obligation.

- Definition

The entire disclosure of revenue from contract with customer to transfer good or service and to transfer nonfinancial asset. Includes, but is not limited to, disaggregation of revenue, credit loss recognized from contract with customer, judgment and change in judgment related to contract with customer, and asset recognized from cost incurred to obtain or fulfill contract with customer. Excludes insurance and lease contracts.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 9
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-9

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 10
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-10

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 15
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-15

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-12

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-12

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-12

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-12

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-12

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (b)(2)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-13

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Name Accounting Standards Codification
-Topic 606
-Publisher FASB
-URI https://asc.fasb.org//606/tableOfContent

+ Details

Acquisition and Divestitures - Summary of Unpaid Principal Balance to Fair Value of Loans and Leases by Portfolio Segment (Details) - USD ($)
$ in Millions

Apr. 01, 2022

Dec. 31, 2023

Jan. 01, 2023

Dec. 31, 2022

Jan. 01, 2022

Dec. 31, 2021

Jan. 01, 2021

Accounts, Notes, Loans and Financing Receivable [Line Items]

Unpaid principal balance

$ 2,166

$ 2,439

$ 2,060

Allowance for credit losses at acquisition

$ (2,439)

$ (2,060)

$ (1,893)

Non PCD Acquired Loans [Member]

Accounts, Notes, Loans and Financing Receivable [Line Items]

Unpaid principal balance

$ 32,896

Other discount

^[1]

(260)

Fair value

32,636

PCD Acquired Loans [Member]

Accounts, Notes, Loans and Financing Receivable [Line Items]

Unpaid principal balance

^[2]

3,411

Allowance for credit losses at acquisition

^[2]

(99)

Other discount

(107)

Fair value

$ 3,205

[1]	Includes approximately $242 million of principal balances not expected to be collected.
[2]	The unpaid principal balance and allowance for credit losses at acquisition is net of charge-offs of $33 million recognized on the PCD loans.

Stock-Based Compensation Plans - Summary of Stock Option Activity (Detail) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Share-Based Payment Arrangement [Abstract]
Stock Options Outstanding, Beginning balance	2,340,062
Stock Options Outstanding, Granted	179,551	138,825	178,441
Stock Options Outstanding, Exercised	(262,837)
Stock Options Outstanding, Expired	(58,112)
Stock Options Outstanding, Ending balance	2,198,664	2,340,062
Stock Options Outstanding, Exercisable	1,807,515
Weighted-Average Exercise Price, Outstanding, Beginning balance	$ 148.78
Weighted-Average Exercise Price, Granted	156
Weighted-Average Exercise Price, Exercised	122.45
Weighted-Average Exercise Price, Expired	155.87
Weighted-Average Exercise Price, Outstanding, Ending balance	152.33	$ 148.78
Weighted-Average Exercise Price, Exercisable	$ 151.67
Weighted-Average Life (In Years), Outstanding, Ending balance	5 years 7 months 6 days
Weighted-Average Life (In Years), Exercisable	5 years
Aggregate Intrinsic Value, Outstanding, Ending balance	$ 6
Aggregate Intrinsic Value, Exercisable	$ 5

Borrowings - Long-term Borrowings (Parenthetical) (Detail)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Variable Rate Term Loans Due 2023 [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2023	2023
3.55% Fixed Rate Due 2023 [Member] \| M&T Bank Corporation [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2023	2023
Interest rate of debt instrument	3.55%	3.55%
4.55% fixed/variable due 2028 [Member] \| M&T Bank Corporation [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2028	2028
Interest rate of debt instrument	4.55%	4.55%
7.41% fixed/variable due 2029 [Member] \| M&T Bank Corporation [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2029	2029
Interest rate of debt instrument	7.41%	7.41%
5.05% fixed/variable due 2034 [Member] \| M&T Bank Corporation [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2034	2034
Interest rate of debt instrument	5.05%	5.05%
Fixed Rate Term Loans 2.90% Due 2025 [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2025	2025
Interest rate of debt instrument	2.90%	2.90%
Fixed Rate Term Loans 5.75% due 2024 [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2024	2024
Interest rate of debt instrument	5.75%	5.75%
Fixed Rate Term Loans 5.40% due 2025 [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2025	2025
Interest rate of debt instrument	5.40%	5.40%
Fixed Rate Term Loans 4.65% due 2026 [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2026	2026
Interest rate of debt instrument	4.65%	4.65%
Fixed Rate Term Loans 4.70% due 2028 [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2028	2028
Interest rate of debt instrument	4.70%	4.70%
4.00% due 2024 [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2024	2024
Interest rate of debt instrument	4.00%	4.00%
3.40% due 2027 [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2027	2027
Interest rate of debt instrument	3.40%	3.40%
BSB Capital Trust I - 8.125%, due 2028 [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2028	2028
Interest rate of debt instrument	8.125%	8.125%
Provident Trust I - 8.29%, due 2028 [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2028	2028
Interest rate of debt instrument	8.29%	8.29%
Southern Financial Statutory Trust I - 10.60%, due 2030 [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2030	2030
Interest rate of debt instrument	10.60%	10.60%
First Maryland Capital I - due 2027 [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2027	2027
First Maryland Capital II - due 2027 [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2027	2027
Allfirst Asset Trust - due 2029 [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2029	2029
BSB Capital Trust III - due 2033 [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2033	2033
Provident Statutory Trust III - Due 2033 [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2033	2033
Southern Financial Capital Trust III - due 2033 [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2033	2033

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
Document and Entity Information - USD ($) $ in Millions	Dec. 31, 2023	Feb. 16, 2024	Jun. 30, 2023
Document Information [Line Items]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2023
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	FY
Entity Registrant Name	M&T BANK CORPORATION
Entity Central Index Key	0000036270
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Interactive Data Current	Yes
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Well-known Seasoned Issuer	Yes
Entity Public Float			$ 19,900,658,494
Entity Common Stock, Shares Outstanding		166,624,291
Entity Shell Company	false
Entity Small Business	false
Entity Emerging Growth Company	false
Entity File Number	1-9861
Entity Incorporation, State or Country Code	NY
Entity Tax Identification Number	16-0968385
Entity Address, City or Town	Buffalo
Entity Address, Address Line One	One M&T Plaza
Entity Address, State or Province	NY
Entity Address, Postal Zip Code	14203
City Area Code	716
Local Phone Number	635-4000
Document Annual Report	true
Document Transition Report	false
ICFR Auditor Attestation Flag	true
Document Financial Statement Error Correction [Flag]	false
Auditor Firm ID	238
Auditor Name	PricewaterhouseCoopers LLP
Auditor Location	Buffalo, NY, United States
Documents Incorporated by Reference [Text Block]	Portions of the Proxy Statement for the 2024 Annual Meeting of Shareholders of M&T Bank Corporation in Parts II and III.
Common Stock [Member]
Document Information [Line Items]
Title of 12(b) Security	Common Stock, $0.50 par value
Trading Symbol	MTB
Security Exchange Name	NYSE
Series H Preferred Stock [Member]
Document Information [Line Items]
Title of 12(b) Security	Perpetual Fixed-to-Floating Rate Non-Cumulative Preferred Stock, Series H
Trading Symbol	MTBPrH
Security Exchange Name	NYSE

Commitments and Contingencies - Commitments and Contingent Liabilities Outstanding (Detail) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Commitments to extend credit
Commercial and industrial	$ 28,566	$ 27,471
Commercial real estate loans to be sold	916	349
Other commercial real estate	5,019	5,084
Residential real estate loans to be sold	163	31
Other residential real estate	331	505
Home equity lines of credit	8,109	8,262
Credit cards	5,578	5,465
Other	413	382
Standby letters of credit	2,289	2,377
Commercial letters of credit	62	65
Financial guarantees and indemnification contracts	4,036	4,022
Commitments to sell real estate loans	$ 1,400	$ 533

Segment Information - Information about Company's Segments (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Segment Reporting Information [Line Items]
Net interest income	$ 7,115	$ 5,822	$ 3,825
Noninterest income	2,528	2,357	2,167
Total income	9,643	8,179	5,992
Provision for credit losses	645	517	(75)
Amortization of core deposit and other intangible assets	62	56	10
Depreciation and other amortization	435	379	314
Other noninterest expense	4,882	4,615	3,288
Income (loss) before taxes	3,619	2,612	2,455
Income tax expense (benefit)	878	620	596
Net income (loss)	2,741	1,992	1,859
Average total assets	205,397	190,252	152,669
Capital expenditures	256	214	149
All Other [Member]
Segment Reporting Information [Line Items]
Net interest income	(346)	109	182
Noninterest income	103	59	61
Total income	(243)	168	243
Provision for credit losses	175	351	(313)
Amortization of core deposit and other intangible assets	62	56	9
Depreciation and other amortization	139	134	114
Other noninterest expense	508	662	264
Income (loss) before taxes	(1,127)	(1,035)	169
Income tax expense (benefit)	(371)	(344)	(5)
Net income (loss)	(756)	(691)	174
Average total assets	70,266	67,635	52,095
Capital expenditures	144	88	79
Commercial Banking [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Net interest income	2,409	2,302	1,558
Noninterest income	658	588	509
Total income	3,067	2,890	2,067
Provision for credit losses	297	66	169
Amortization of core deposit and other intangible assets			1
Depreciation and other amortization	39	39	39
Other noninterest expense	1,307	1,085	748
Income (loss) before taxes	1,424	1,700	1,110
Income tax expense (benefit)	385	458	297
Net income (loss)	1,039	1,242	813
Average total assets	80,243	69,960	53,578
Capital expenditures	2	2	3
Retail Banking [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Net interest income	4,352	3,008	1,929
Noninterest income	762	703	831
Total income	5,114	3,711	2,760
Provision for credit losses	173	101	69
Depreciation and other amortization	249	198	152
Other noninterest expense	2,208	2,009	1,508
Income (loss) before taxes	2,484	1,403	1,031
Income tax expense (benefit)	646	364	266
Net income (loss)	1,838	1,039	765
Average total assets	51,213	49,059	43,736
Capital expenditures	104	122	55
Institutional Services and Wealth Management [ Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Net interest income	700	403	156
Noninterest income	1,005	1,007	766
Total income	1,705	1,410	922
Provision for credit losses		(1)
Depreciation and other amortization	8	8	9
Other noninterest expense	859	859	768
Income (loss) before taxes	838	544	145
Income tax expense (benefit)	218	142	38
Net income (loss)	620	402	107
Average total assets	3,675	3,598	3,260
Capital expenditures	$ 6	$ 2	$ 12

Goodwill and Other Intangible Assets - Additional Information (Detail)	3 Months Ended	12 Months Ended
	Dec. 31, 2023 USD ($) ReportableSegment	Dec. 31, 2023 USD ($) ReportableSegment	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Goodwill And Other Intangible Assets [Line Items]
Amortization of core deposit and other intangible assets		$ 62,000,000	$ 56,000,000	$ 10,000,000
Changes to goodwill assigned to reporting unit	$ 0
Number of reportable segments \| ReportableSegment	3	3
Impairment of goodwill		$ 0
Minimum [Member]
Goodwill And Other Intangible Assets [Line Items]
Estimated useful lives	3 years	3 years
Maximum [Member]
Goodwill And Other Intangible Assets [Line Items]
Estimated useful lives	7 years	7 years
Core Deposit and Other Intangible Assets [Member]
Goodwill And Other Intangible Assets [Line Items]
Estimated useful lives	6 years	6 years
Amortization of core deposit and other intangible assets		$ 62,000,000	$ 56,000,000	$ 10,000,000
Core Deposit and Other Intangible Assets [Member] \| Minimum [Member]
Goodwill And Other Intangible Assets [Line Items]
Estimated useful lives	3 years	3 years
Core Deposit and Other Intangible Assets [Member] \| Maximum [Member]
Goodwill And Other Intangible Assets [Line Items]
Estimated useful lives	7 years	7 years

Earnings Per Common Share - Computations of Basic Earnings Per Common Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income available to common shareholders:
Net Income (Loss)	$ 2,741	$ 1,992	$ 1,859
Less: Preferred stock dividends	(100)	(97)	(73)
Net income available to common equity	2,641	1,895	1,786
Less: Income attributable to unvested stock-based compensation awards	(5)	(4)	(9)
Net income available to common shareholders	$ 2,636	$ 1,891	$ 1,777
Weighted-average shares outstanding:
Common shares outstanding (including common stock issuable) and unvested stock-based compensation awards	166,662	163,489	129,539
Less: Unvested stock-based compensation awards	(301)	(315)	(890)
Weighted-average shares outstanding	166,361	163,174	128,649
Basic earnings per common share	$ 15.85	$ 11.59	$ 13.81

Parent Company Financial Statements - Condensed Statement of Income (Detail) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Expense
Interest on short-term borrowings	$ 292	$ 19
Interest on long-term borrowings	400	111	$ 62
Other expense	5,379	5,050	3,612
Income tax credits	(878)	(620)	(596)
Equity in undistributed income of subsidiaries
Net income	$ 2,741	$ 1,992	$ 1,859
Net income per common share
Basic	$ 15.85	$ 11.59	$ 13.81
Diluted	$ 15.79	$ 11.53	$ 13.8
Parent Company [Member]
Income
Dividends from consolidated subsidiaries	$ 2,041	$ 2,508	$ 1,025
Income (Loss) from Equity Method Investments	20	30	30
Other income	6	(7)	3
Total income	2,067	2,531	1,058
Expense
Interest on short-term borrowings		6
Interest on long-term borrowings	182	57	24
Other expense	40	50	36
Total expense	222	113	60
Income before income taxes and equity in undistributed income of subsidiaries	1,845	2,418	998
Income tax credits	49	22	6
Income before equity in undistributed income of subsidiaries	1,894	2,440	1,004
Equity in undistributed income of subsidiaries
Net income of subsidiaries	2,888	2,060	1,880
Less: dividends received	(2,041)	(2,508)	(1,025)
Equity in undistributed income of subsidiaries	847	(448)	855
Net income	$ 2,741	$ 1,992	$ 1,859
Net income per common share
Basic	$ 15.85	$ 11.59	$ 13.81
Diluted	$ 15.79	$ 11.53	$ 13.80

Significant Accounting Policies - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2023
Significant Accounting Policies [Line Items]
Delinquent period of loans resulting in accrued interest being charged against income	90 days
Delinquent period of loans secured by real estate resulting in charge off	150 days
Delinquent period of loans resulting in accrued interest being charged against income description	Certain loans greater than 90 days delinquent continue to accrue interest if they are well-secured and in the process of collection. Loans less than 90 days delinquent are deemed to have an insignificant delay in payment and generally continue to accrue interest
Maximum [Member]
Significant Accounting Policies [Line Items]
Consumer loan delinquent period threshold for consideration for charge off	180 days
Estimated useful lives	7 years
Minimum [Member]
Significant Accounting Policies [Line Items]
Consumer loan delinquent period threshold for consideration for charge off	91 days
Estimated useful lives	3 years
Income tax benefit recognition criteria percentage threshold	50.00%

Acquisition and Divestitures - Summary of Acquisition, Pro Forma Information (Details) - Peoples United Financial Inc [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total revenues	$ 8,631	$ 8,076
Net income	$ 2,158	$ 2,391

Premises and equipment (Tables)

12 Months Ended

Dec. 31, 2023

Property, Plant and Equipment [Abstract]

Summary of Premises and Equipment

The detail of premises and equipment was as follows:


	December 31,
(Dollars in millions)	2023		2022
Land	$	148	$	149
Buildings		685		654
Leasehold improvements		413		387
Furniture and equipment		1,097		1,004
		2,343		2,194
Less: accumulated depreciation and amortization		1,220		1,156
Right-of-use assets — operating leases		616		616
Premises and equipment, net	$	1,739	$	1,654

Summary of Lease Costs for Operating Leases, Cash Paid Toward Lease Liabilities, and Weighted-Average Remaining Term and Discount Rates of Operating Leases


	Year Ended December 31,
(Dollars in millions)	2023			2022			2021
Lease cost
Operating lease cost	$	154		$	139		$	102
Short-term lease cost		—			8			—
Variable lease cost		4			4			4
Total lease cost	$	158		$	151		$	106

Other information
Right-of-use assets:
Obtained in exchange for new operating lease liabilities	$	134		$	138		$	58
Acquired in business combination		—			226			—
Cash paid toward lease liabilities		158			143			107
Weighted-average remaining lease term	7 years			7 years			6 years
Weighted-average discount rate		3.37	%		2.97	%		2.51	%

Summary of Minimum Lease Payments Under Noncancelable Operating Leases

Minimum lease payments under noncancelable operating leases are summarized in the following table.


(Dollars in millions)
Year ending December 31:
2024	$	162
2025		145
2026		122
2027		101
2028		75
Later years		208
Total lease payments		813
Less: imputed interest		96
Total	$	717

Allowance for Credit Losses - Additional Information (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($)
Maximum [Member]
Loans And Leases Receivable [Line Items]
Loan delinquent period	150 days
Minimum [Member]
Loans And Leases Receivable [Line Items]
Loan delinquent period	90 days
Minimum [Member] \| Commercial Loans and Commercial Real Estate [Member]
Loans And Leases Receivable [Line Items]
Amount of real estate loan as reported as accruing or nonaccruing	$ 5

Variable interest entities and asset securitizations

12 Months Ended

Dec. 31, 2023

Text Block [Abstract]

Variable interest entities and asset securitizations

20. Variable interest entities and asset securitizations

The Company’s securitization activity includes securitizing loans originated for sale into government issued or guaranteed mortgage-backed securities. The Company has not recognized any losses as a result of having securitized assets.

In August 2023, a subsidiary of M&T Bank issued asset-backed notes secured by equipment finance loans and leases. Approximately $666 million of such loans and leases were sold into a special purpose trust which in turn issued asset-backed notes to investors. The loans and leases continue to be serviced by the subsidiary. A total of $550 million of such notes, representing the senior-most notes in the securitization, were purchased by third parties. Those asset-backed notes had a weighted-average estimated life of approximately two years and a weighted-average interest rate of 5.84% at the time of securitization. Additionally, $88 million of asset-backed notes representing subordinate note classes and other residual interests were issued by the trust and retained by the Company. As a result of the retention of the subordinate interests and its continued role as servicer of the loans and leases, the Company is considered to be the primary beneficiary of the securitization trust and, accordingly, the trust has been included in the Company's consolidated financial statements. At December 31, 2023, the remaining balance of the loans and leases in trust was $599 million and the outstanding asset-backed notes issued to third party investors was $474 million.

As described in note 9, the Junior Subordinated Debentures are held by various trusts and were issued in connection with the issuance by those trusts of Preferred Capital Securities and Common Securities. M&T owns the Common Securities of those trust entities. The Company is not considered to be the primary beneficiary of those entities and, accordingly, the trusts are not included in the Company’s consolidated financial statements. At each of December 31, 2023 and 2022, the Company included the Junior Subordinated Debentures as “long-term borrowings” in its Consolidated Balance Sheet and recognized $22 million, in other assets for its “investment” in the Common Securities of the trusts that will be concomitantly repaid to M&T by the respective trust from the proceeds of M&T’s repayment of the Junior Subordinated Debentures associated with Preferred Capital Securities described in note 9.

The Company has invested as a limited partner in various partnerships that collectively had total assets of approximately $9.8 billion at December 31, 2023 and $9.2 billion at December 31, 2022. Those partnerships generally construct or acquire properties, including properties and facilities that produce renewable energy, for which the investing partners are eligible to receive certain federal income tax credits in accordance with government guidelines. Such investments also typically provide tax deductible losses to the partners. The partnership investments also assist the Company in achieving its community reinvestment initiatives. As a limited partner, there is no recourse to the Company by creditors of the partnerships. However, the tax credits that result from the Company’s investments in such partnerships are generally subject to recapture should a partnership fail to comply with the respective government regulations. The Company's carrying amount of its investments in such

partnerships was $1.5 billion, including $441 million of unfunded commitments, at December 31, 2023 and $1.5 billion, including $545 million of unfunded commitments at December 31, 2022. Contingent commitments to provide additional capital contributions to these partnerships were $55 million at December 31, 2023. The Company has not provided financial or other support to the partnership that was not contractually required. The Company's maximum exposure to loss from its investments in such partnerships as of December 31, 2023 was $2.1 billion, including possible recapture of tax credits. Management currently estimates that no material losses are probable as a result of the Company’s involvement with such entities. The Company, in its position as limited partner, does not direct the activities that most significantly impact the economic performance of the partnerships and, therefore, in accordance with the accounting provisions for variable interest entities, the partnership entities are not included in the Company’s consolidated financial statements. The Company’s investment in qualified affordable housing projects is amortized to income taxes in the Consolidated Statement of Income as tax credits and other tax benefits resulting from deductible losses associated with the projects are received.

The Company serves as investment advisor for certain registered money-market funds. The Company has no explicit arrangement to provide support to those funds, but may waive portions of its allowable management fees as a result of market conditions.

Pension Plans and Other Postretirement Benefits - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Defined Benefit Plan Disclosure [Line Items]
Minimum pension liability	$ 155,000
Minimum pension liability adjustment net of tax	115,000
Decrease in minimum liability adjustment		$ 118,000
Defined contribution pension and retirement savings plans total expense	$ 56,000	45,000	$ 40,000
Assumptions used calculating net periodic benefit sensitivity rate increase decrease discount rate	25.00%
Effect of 25 basis point increase in rate of return on pension expense	$ 8,000
Effect of 25 basis point decrease in rate of return on pension expense	1,000
Effect of 25 basis point decrease in discount rate on benefit obligation	62,000
Effect of 25 basis point increase in discount rate on benefit obligation	$ 65,000
Annual rate of increase in health care cost assumed for next fiscal year	6.75%
Defined Benefit Plan, ultimate health care cost trend rate	5.00%
Period for decreasing the annual rate	over seven years
Defined benefit pension plans	$ 668,000
Percentage of total assets	21.00%
Defined benefit plan fair value of plan assets	$ 3,141,000	2,938,000
Qualified benefit pension plans	$ 0
Percentage of pension plan assets that is not exceeded by investment in security of single Non-US Government of Government agency	10.00%
Percentage of eligible employees contribution for Retirement Savings Plan	50.00%
Percentage of employer matching contribution to employee's contribution	100.00%
Maximum employer contribution on Employee's qualified contribution	5.00%
Qualified defined contribution plans expense during the period	$ 96,000	$ 84,000	63,000
Increment in amortization period		16 years
Defined benefit pension plan, reduction to change in amortization		$ 36,000
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Immediate Recognition of Actuarial Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]		Other Noninterest Expense
Equity Securities [Member] \| Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target allocations for plan assets	5.00%
Equity Securities [Member] \| Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target allocations for plan assets	60.00%
Total Debt Securities [Member] \| Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target allocations for plan assets	10.00%
Total Debt Securities [Member] \| Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target allocations for plan assets	65.00%
Other Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	$ 668,000	$ 632,000
Other Securities [Member] \| Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target allocations for plan assets	5.00%
Other Securities [Member] \| Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target allocations for plan assets	60.00%
M&T Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	$ 112,000	118,000
Supplemental Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	146,000	152,000
Accumulated benefit obligation	146,000	152,000
Employer contribution	18,000	14,000
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	2,369,000	2,379,000	2,420,000
Accumulated benefit obligation	2,400,000	$ 2,400,000
Minimum pension liability	$ 191,000
Discount rate	5.00%	5.00%
Defined benefit plan fair value of plan assets	$ 3,145,000	$ 2,942,000	2,596,000
Employer contribution	18,000	14,000
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	57,000	$ 60,000	$ 52,000
Minimum pension liability	$ 36,000
Discount rate	5.00%	5.00%
Employer contribution	$ 3,000	$ 3,000

Borrowings - Long-term Borrowings (Detail) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Schedule Of Borrowings [Line Items]
Asset-backed notes	$ 474
Other	15	$ 15
Long-term borrowings	8,201	3,965
Variable Rate Term Loans Due 2023 [Member] \| M&T Bank Corporation [Member]
Schedule Of Borrowings [Line Items]
Variable\fixed rates term loan amount		250
3.55% Fixed Rate Due 2023 [Member] \| M&T Bank Corporation [Member]
Schedule Of Borrowings [Line Items]
Variable\fixed rates term loan amount		494
4.55% fixed/variable due 2028 [Member] \| M&T Bank Corporation [Member]
Schedule Of Borrowings [Line Items]
Variable\fixed rates term loan amount	484	477
7.41% fixed/variable due 2029 [Member] \| M&T Bank Corporation [Member]
Schedule Of Borrowings [Line Items]
Variable\fixed rates term loan amount	1,028
5.05% fixed/variable due 2034 [Member] \| M&T Bank Corporation [Member]
Schedule Of Borrowings [Line Items]
Variable\fixed rates term loan amount	970
Fixed Rate Term Loans 5.75% due 2024 [Member]
Schedule Of Borrowings [Line Items]
Subordinated notes	76	77
Fixed Rate Term Loans 4.65% due 2026 [Member]
Schedule Of Borrowings [Line Items]
Variable\fixed rates term loan amount	1,296
Fixed Rate Term Loans 4.70% due 2028 [Member]
Schedule Of Borrowings [Line Items]
Variable\fixed rates term loan amount	1,196
4.00% due 2024 [Member]
Schedule Of Borrowings [Line Items]
Subordinated notes	401	404
Fixed Rate Term Loans 5.40% due 2025 [Member]
Schedule Of Borrowings [Line Items]
Variable\fixed rates term loan amount	499	499
Fixed Rate Term Loans 2.90% Due 2025 [Member]
Schedule Of Borrowings [Line Items]
Variable\fixed rates term loan amount	750	750
3.40% due 2027 [Member]
Schedule Of Borrowings [Line Items]
Subordinated notes	472	463
BSB Capital Trust I - 8.125%, due 2028 [Member]
Schedule Of Borrowings [Line Items]
Junior subordinated debentures associated with preferred capital securities	16	16
Provident Trust I - 8.29%, due 2028 [Member]
Schedule Of Borrowings [Line Items]
Junior subordinated debentures associated with preferred capital securities	32	31
Southern Financial Statutory Trust I - 10.60%, due 2030 [Member]
Schedule Of Borrowings [Line Items]
Junior subordinated debentures associated with preferred capital securities	7	7
First Maryland Capital I - due 2027 [Member]
Schedule Of Borrowings [Line Items]
Junior subordinated debentures associated with preferred capital securities	150	150
First Maryland Capital II - due 2027 [Member]
Schedule Of Borrowings [Line Items]
Junior subordinated debentures associated with preferred capital securities	153	152
Allfirst Asset Trust - due 2029 [Member]
Schedule Of Borrowings [Line Items]
Junior subordinated debentures associated with preferred capital securities	98	97
BSB Capital Trust III - due 2033 [Member]
Schedule Of Borrowings [Line Items]
Junior subordinated debentures associated with preferred capital securities	15	15
Provident Statutory Trust III - Due 2033 [Member]
Schedule Of Borrowings [Line Items]
Junior subordinated debentures associated with preferred capital securities	60	59
Southern Financial Capital Trust III - due 2033 [Member]
Schedule Of Borrowings [Line Items]
Junior subordinated debentures associated with preferred capital securities	$ 9	$ 9

Acquisition and divestitures (Tables)

12 Months Ended

Dec. 31, 2023

Business Combinations [Abstract]

Summary of Identifiable Assets Acquired, Liabilities Assumed and Preferred Stock Exchanged as of Acquisition

The consideration paid for People’s United common equity and the preliminary amounts of identifiable assets acquired, liabilities assumed and preferred stock converted as of the acquisition date follows.


(Dollars in millions)
Consideration:
Common stock issued (50,325,004 shares)	$	8,286
Common stock awards converted		105
Cash		2
Total consideration		8,393

Net assets acquired:
Identifiable assets:
Cash and due from banks		396
Interest-bearing deposits at banks		9,193
Investment securities		11,575
Loans and leases		35,841
Core deposit and other intangible assets		261
Other assets		2,979
Total identifiable assets acquired		60,245
Liabilities and preferred stock:
Deposits		52,968
Borrowings		1,389
Other liabilities		1,142
Total liabilities assumed		55,499
Preferred stock		261
Total liabilities and preferred stock		55,760
Net assets acquired		4,485
Goodwill	$	3,908

Summary of Unpaid Principal Balance to Fair Value of Loans and Leases by Portfolio Segment

The following table reconciles the unpaid principal balance to the fair value of loans and leases at April 1, 2022:


(Dollars in millions)	PCD				Non-PCD
Unpaid principal balance	$	3,411		(a)	$	32,896
Allowance for credit losses at acquisition		(99	)	(a)		—
Other discount		(107	)			(260	)	(b)
Fair value	$	3,205			$	32,636

(a)

The unpaid principal balance and allowance for credit losses at acquisition is net of charge-offs of $33 million recognized on the PCD loans.

(b)

Includes approximately $242 million of principal balances not expected to be collected.

Summary of Acquisition, Pro Forma Information

The following table presents certain pro forma information as if People’s United had been acquired on January 1, 2021.


	Pro forma (Unaudited)
(Dollars in millions)	2022		2021
Total revenues (a)	$	8,631	$	8,076
Net income		2,158		2,391

(a)

Represents the total of net interest income and other income.

Summary of Merger Related Expenses

A summary of merger-related expenses included in the Consolidated Statement of Income in 2022 and 2021 follows.


(Dollars in millions)	2022		2021
Salaries and employee benefits	$	102	$	—
Equipment and net occupancy		7		—
Outside data processing software		5		1
Professional and other services		72		37
Advertising and marketing		9		1
Other cost of operations		143		5
Other expense	$	338	$	44

Income Taxes - Components of Income Tax Expense (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Current
Federal	$ 580	$ 367	$ 332
State and local	228	143	85
Total current	808	510	417
Deferred
Federal	(64)	(18)	72
State and local	(33)	(12)	15
Total deferred	(97)	(30)	87
Amortization of investments in qualified affordable housing projects	167	140	92
Income taxes	$ 878	$ 620	$ 596

Goodwill and other intangible assets (Tables)

12 Months Ended

Dec. 31, 2023

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of Finite-Lived Intangible Assets

A summary of total amortizing intangible assets follows.


(Dollars in millions)	Gross Carrying Amount		Accumulated Amortization		Net Carrying Amount
December 31, 2023
Core deposit	$	218	$	90	$	128
Other		43		24		19
Total	$	261	$	114	$	147
December 31, 2022
Core deposit	$	218	$	41	$	177
Other		43		11		32
Total	$	261	$	52	$	209

Summary of Estimated Amortization Expense

Estimated amortization expense in future years for such intangible assets is as follows:


(Dollars in millions)
Year ending December 31:
2024	$	53
2025		38
2026		27
2027		18
2028		9
Later years		2
	$	147

Summary of Goodwill Assigned to Reportable Segments for Purposes of Testing for Impairment

A summary of goodwill assigned to each of the Company’s reportable segments as of December 31, 2023 and 2022 for purposes of testing for impairment is as follows:


	December 31,		2023			December 31,
(Dollars in millions)	2022		Transactions (a)			2023
Commercial Bank	$	5,076	$	—		$	5,076
Retail Bank		3,089		—			3,089
Institutional Services & Wealth Management		325		(25	)		300
All Other		—		—			—
Total	$	8,490	$	(25	)	$	8,465

(a)

The decrease in Institutional Services & Wealth Management represents goodwill allocated to the CIT business sold in April 2023. Further information regarding that transaction is provided in note 2.

- Definition

Tabular disclosure of goodwill by reportable segment and in total which includes a rollforward schedule.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 350
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 24
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482548/350-20-55-24

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 350
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482573/350-20-50-1

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 350
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (h)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482573/350-20-50-1

Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 350
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482573/350-20-50-1

Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 350
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482573/350-20-50-1

Reference 6: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 350
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482573/350-20-50-1

Reference 7: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 350
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482573/350-20-50-1

Reference 8: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 350
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (e)
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+ Details

Fair Value Measurements - Changes in Level 3 Assets and Liabilities Measured at Estimated Fair Value on Recurring Basis (Detail) - Fair Value Measurements, Recurring [Member] - Significant Unobservable Inputs (Level 3) [Member] - Other Assets and Other Liabilities [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning Balance	$ (46)	$ 6	$ 43
Total gains realized/unrealized:
Included in earnings	$ 36	$ (34)	$ 126
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Revenue from Contract with Customer, Including Assessed Tax	Revenue from Contract with Customer, Including Assessed Tax	Revenue from Contract with Customer, Including Assessed Tax
Transfers out of Level 3	$ (7)	$ (18)	$ (163)
Ending Balance	(17)	(46)	6
Changes in net unrealized gains (losses) included in earnings related to assets/ instruments still held at end of period	$ 15	$ (46)	$ 9

Derivative Financial Instruments - Information about Interest Rate Swap Agreements (Parenthetical) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Derivative [Line Items]
Notional Amount	$ 26,977	$ 17,400
Fair Value Hedges [Member]
Derivative [Line Items]
Impact of estimated fair value gain (losses) on hedging instruments	43	65
Fair Value Hedges [Member] \| Forward-Starting Interest Rate Swap Agreements [Member]
Derivative [Line Items]
Notional Amount	4,700
Cash Flow Hedges [Member]
Derivative [Line Items]
Impact of estimated fair value gain (losses) on hedging instruments	214	330
Cash Flow Hedges [Member] \| Forward-Starting Interest Rate Swap Agreements [Member]
Derivative [Line Items]
Notional Amount	$ 1,000	$ 9,000

Goodwill and Other Intangible Assets - Summary of Goodwill Assigned to Reportable Segments for Purposes of Testing for Impairment (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Goodwill [Line Items]
Goodwill	$ 8,465	$ 8,490
2023 Transactions	(25)
Commercial Banking [Member]
Goodwill [Line Items]
Goodwill	5,076	5,076
Retail Banking [Member]
Goodwill [Line Items]
Goodwill	3,089	3,089
Institutional Services & Wealth Management [Member]
Goodwill [Line Items]
Goodwill	300	$ 325
2023 Transactions	$ (25)

- Definition

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References + Details

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Regulatory Matters - Capital Ratios and Amounts of Company and its Banking Subsidiaries (Detail) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
M&T Bank Corporation [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Amount	$ 16,908	$ 15,562
Ratio	10.98%	10.44%
Amount	$ 18,918	$ 17,573
Ratio	0.1229	0.1179
Amount	$ 21,533	$ 20,260
Ratio	0.1399	0.136
Amount	$ 18,918	$ 17,573
Ratio	0.0943	0.0923
M&T Bank [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Amount	$ 17,667	$ 16,674
Ratio	11.53%	11.23%
Amount	$ 17,667	$ 16,674
Ratio	0.1153	0.1123
Amount	$ 19,884	$ 18,888
Ratio	0.1297	0.1272
Amount	$ 17,667	$ 16,674
Ratio	0.0883	0.0877
Wilmington Trust, N.A. [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Amount	$ 583	$ 586
Ratio	263.48%	254.50%
Amount	$ 583	$ 586
Ratio	2.6348	2.545
Amount	$ 584	$ 587
Ratio	2.6385	2.549
Amount	$ 583	$ 586
Ratio	0.86	0.8573

Regulatory matters

12 Months Ended

Dec. 31, 2023

Broker-Dealer, Net Capital Requirement, SEC Regulation [Abstract]

Regulatory matters

24. Regulatory matters

Payment of dividends by M&T’s banking subsidiaries is restricted by various legal and regulatory limitations. Dividends from any banking subsidiary to M&T are limited by the amount of earnings of the banking subsidiary in the current year and the preceding two years. For purposes of this test, at December 31, 2023, approximately $1.7 billion was available for payment of dividends to M&T from banking subsidiaries. M&T may pay dividends and repurchase stock only in accordance with a capital plan that the Federal Reserve has not objected to.

Banking regulations prohibit extensions of credit by the subsidiary banks to M&T unless appropriately secured by assets. Securities of affiliates are not eligible as collateral for this purpose.

M&T and its subsidiary banks are required to comply with applicable capital adequacy regulations established by the federal banking agencies. Failure to meet minimum capital requirements can result in certain mandatory, and possibly additional discretionary, actions by regulators that, if undertaken, could have a material effect on the Company’s financial statements. Pursuant to the rules in effect as of December 31, 2023, the required minimum and well capitalized capital ratios are as follows:


				Well
	Minimum			Capitalized
M&T (Consolidated)
CET1 to RWA		4.5	%
Tier 1 capital to RWA		6.0			6.0	%
Total capital to RWA		8.0			10.0
Leverage — Tier 1 capital to average total assets, as defined		4.0

				Well
	Minimum			Capitalized
Bank Subsidiaries
CET1 to RWA		4.5	%		6.5	%
Tier 1 capital to RWA		6.0			8.0
Total capital to RWA		8.0			10.0
Leverage — Tier 1 capital to average total assets, as defined		4.0			5.0

Capital regulations require buffers in addition to the minimum risk-based capital ratios noted above. M&T is subject to a SCB requirement that is determined through the Federal Reserve’s supervisory stress tests and M&T’s bank subsidiaries are subject to a 2.5% capital conservation buffer requirement. The buffer requirement must be composed entirely of CET1. In June 2023, the Federal Reserve released the results of its most recent supervisory stress tests. Based on those results on October 1, 2023, M&T's SCB of 4.0% became effective. Accordingly, at December 31, 2023 M&T is subject to a CET1 capital requirement of 8.5% (a sum of the SCB and the minimum CET1 capital ratio).

The capital ratios and amounts of the Company and its banking subsidiaries as of December 31, 2023 and 2022 are presented below:


(Dollars in millions)	M&T (Consolidated)			M&T Bank			Wilmington Trust, N.A.
December 31, 2023:
CET1 capital
Amount	$	16,908		$	17,667		$	583
Ratio(a)		10.98	%		11.53	%		263.48	%
Tier 1 capital
Amount	$	18,918		$	17,667		$	583
Ratio(a)		12.29	%		11.53	%		263.48	%
Total capital
Amount	$	21,533		$	19,884		$	584
Ratio(a)		13.99	%		12.97	%		263.85	%
Leverage
Amount	$	18,918		$	17,667		$	583
Ratio(b)		9.43	%		8.83	%		86.00	%
December 31, 2022:
CET1 capital
Amount	$	15,562		$	16,674		$	586
Ratio(a)		10.44	%		11.23	%		254.50	%
Tier 1 capital
Amount	$	17,573		$	16,674		$	586
Ratio(a)		11.79	%		11.23	%		254.50	%
Total capital
Amount	$	20,260		$	18,888		$	587
Ratio(a)		13.60	%		12.72	%		254.90	%
Leverage
Amount	$	17,573		$	16,674		$	586
Ratio(b)		9.23	%		8.77	%		85.73	%

(a)

The ratio of capital to RWA, as defined by regulation.

(b)

The ratio of capital to average assets, as defined by regulation.

- Definition

The entire disclosure for regulatory capital requirement for depository and lending institutions. Institutions include, but not are not limited to, finance company, insured depository institution, bank holding company, savings and loan association holding company, bank and savings institution not federally insured, mortgage company, foreign financial institution and credit union.

+ References + Details

Shareholders' equity (Tables)

12 Months Ended

Dec. 31, 2023

Equity [Abstract]

Issued and Outstanding Preferred Stock

Issued and outstanding preferred stock of M&T at each of December 31, 2023 and 2022 is presented below:


(Dollars in millions)	Shares Issued and Outstanding		Carrying Value
Series E (a)
Fixed-to-Floating Rate Non-cumulative Perpetual Preferred Stock $1,000 liquidation preference per share		350,000	$	350
Series F (b)
Fixed-to-Floating Rate Non-cumulative Perpetual Preferred Stock $10,000 liquidation preference per share		50,000		500
Series G (c)
Fixed-Rate Reset Non-cumulative Perpetual Preferred Stock $10,000 liquidation preference per share		40,000		400
Series H (d)
Fixed-to-Floating Rate Non-cumulative Perpetual Preferred Stock $25 liquidation preference per share		10,000,000		261
Series I (e)
Fixed-Rate Reset Non-cumulative Perpetual Preferred Stock $10,000 liquidation preference per share		50,000		500

(a)

Dividends, if declared, are paid semi-annually at a rate of 6.45% through February 14, 2024 and thereafter will be paid quarterly at a rate of the three-month SOFR plus 387 basis points. The shares are redeemable in whole or in part on or after February 15, 2024. Notwithstanding M&T’s option to redeem the shares, if an event occurs such that the shares no longer qualify as Tier 1 capital, M&T may redeem all of the shares within 90 days following that occurrence. Declared dividends per share were $64.50 in each of 2023, 2022 and 2021.

(b)

Dividends, if declared, are paid semi-annually at a rate of 5.125% through October 31, 2026 and thereafter will be paid quarterly at a rate of the three-month SOFR plus 378 basis points. The shares are redeemable in whole or in part on or after November 1, 2026. Notwithstanding M&T’s option to redeem the shares, if an event occurs such that the shares no longer qualify as Tier 1 capital, M&T may redeem all of the shares within 90 days following that occurrence. Declared dividends per share were $512.50 in each of 2023, 2022 and 2021.

(c)

Dividends, if declared, are paid semi-annually at a rate of 5.0% through July 31, 2024 and thereafter will be paid semi-annually at a rate of the five-year U.S. Treasury rate plus 3.174%. The shares are redeemable in whole or in part on or after August 1, 2024. Notwithstanding M&T’s option to redeem the shares, if an event occurs such that the shares no longer qualify as Tier 1 capital, M&T may redeem all of the shares within 90 days following that occurrence. Declared dividends per share were $500.00 in each of 2023, 2022 and 2021.

(d)

Dividends, if declared, are paid quarterly at a rate of 5.625% through December 14, 2026 and thereafter will be paid quarterly at a rate of the three-month SOFR plus 428 basis points. The shares are redeemable in whole or in part on or after April 1, 2027. Notwithstanding M&T's option to redeem the shares, if an event occurs such that the shares no longer qualify as Tier 1 capital, M&T may redeem all of the shares within 90 days following that occurrence. Dividends declared per share were $1.4063 in 2023 and $1.0547 in 2022.

(e)

Dividends, if declared, are paid semi-annually at a rate of 3.5% through August 31, 2026 and thereafter will be paid semi-annually at a rate of the five-year U.S. Treasury rate plus 2.679%. The shares are redeemable in whole or in part on or after September 1, 2026. Notwithstanding M&T’s option to redeem the shares, if an event occurs such that the shares no longer qualify as Tier 1 capital, M&T may redeem all of the shares within 90 days following that occurrence. Dividends declared per share were $350.00 in 2023, $356.806 in 2022 and $94.306 in 2021.

- Definition

Tabular disclosure of an entity's stock, including par or stated value per share, number and dollar amount of share subscriptions, shares authorized, shares issued, shares outstanding, number and dollar amount of shares held in an employee trust, dividend per share, total dividends, share conversion features, par value plus additional paid in capital, the value of treasury stock and other information necessary to a fair presentation, and EPS information. Stock by class includes common, convertible, and preferred stocks which are not redeemable or redeemable solely at the option of the issuer. Includes preferred stock with redemption features that are solely within the control of the issuer and mandatorily redeemable stock if redemption is required to occur only upon liquidation or termination of the reporting entity. If more than one issue is outstanding, state the title of each issue and the corresponding dollar amount; dollar amount of any shares subscribed but unissued and the deduction of subscriptions receivable there from; number of shares authorized, issued, and outstanding.

+ References

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+ Details

Segment information (Tables)

12 Months Ended

Dec. 31, 2023

Segment Reporting [Abstract]

Information about Company's Segments

Information about the Company’s segments is presented in the accompanying table.


	For the Years Ended December 31,
	Commercial Bank									Retail Bank							Institutional Services and Wealth Management
(Dollars in millions)	2023			2022			2021			2023		2022		2021			2023		2022			2021
Net interest income (a)	$	2,409		$	2,302		$	1,558		$	4,352	$	3,008	$	1,929		$	700	$	403		$	156
Noninterest income		658			588			509			762		703		831			1,005		1,007			766
		3,067			2,890			2,067			5,114		3,711		2,760			1,705		1,410			922
Provision for credit losses		297			66			169			173		101		69			—		(1	)		—
Amortization of core deposit and other intangible assets		—			—			1			—		—		—			—		—			—
Depreciation and other amortization		39			39			39			249		198		152			8		8			9
Other noninterest expense		1,307			1,085			748			2,208		2,009		1,508			859		859			768
Income (loss) before taxes		1,424			1,700			1,110			2,484		1,403		1,031			838		544			145
Income tax expense (benefit)		385			458			297			646		364		266			218		142			38
Net income (loss)	$	1,039		$	1,242		$	813		$	1,838	$	1,039	$	765		$	620	$	402		$	107
Average total assets	$	80,243		$	69,960		$	53,578		$	51,213	$	49,059	$	43,736		$	3,675	$	3,598		$	3,260
Capital expenditures	$	2		$	2		$	3		$	104	$	122	$	55		$	6	$	2		$	12

	All Other									Total
(Dollars in millions)	2023			2022			2021			2023		2022		2021
Net interest income (a)	$	(346	)	$	109		$	182		$	7,115	$	5,822	$	3,825
Noninterest income		103			59			61			2,528		2,357		2,167
		(243	)		168			243			9,643		8,179		5,992
Provision for credit losses		175			351			(313	)		645		517		(75	)
Amortization of core deposit and other intangible assets		62			56			9			62		56		10
Depreciation and other amortization		139			134			114			435		379		314
Other noninterest expense		508			662			264			4,882		4,615		3,288
Income (loss) before taxes		(1,127	)		(1,035	)		169			3,619		2,612		2,455
Income tax expense (benefit)		(371	)		(344	)		(5	)		878		620		596
Net income (loss)	$	(756	)	$	(691	)	$	174		$	2,741	$	1,992	$	1,859
Average total assets	$	70,266		$	67,635		$	52,095		$	205,397	$	190,252	$	152,669
Capital expenditures	$	144		$	88		$	79		$	256	$	214	$	149

(a)

Net interest income is the difference between actual taxable-equivalent interest earned on assets and interest paid on liabilities by a segment and a funding charge (credit) based on the Company’s internal funds transfer pricing methodology. Segments are charged a cost to fund any assets (e.g. loans) and are paid a funding credit for any funds provided (e.g. deposits). The taxable-equivalent adjustment aggregated $54 million in 2023, $39 million in 2022 and $15 million in 2021 and is eliminated in “All Other” net interest income and income tax expense (benefit).

Intersegment Activity Eliminated in Arriving at Consolidated Totals was Included in "All Other" Category

The amount of intersegment activity eliminated in arriving at consolidated totals was included in the “All Other” category as follows:


	Year Ended December 31,
(Dollars in millions)	2023			2022			2021
Revenues	$	(17	)	$	(14	)	$	(12	)
Expenses		(3	)		(2	)		(2	)
Income taxes		(4	)		(3	)		(3	)
Net income		(10	)		(9	)		(7	)

Capitalized servicing assets

12 Months Ended

Dec. 31, 2023

Transfers and Servicing [Abstract]

Capitalized servicing assets

7. Capitalized servicing assets

Changes in capitalized servicing assets were as follows:


	Year Ended December 31,
	Residential Mortgage Loans									Commercial Mortgage Loans
(Dollars in millions)	2023			2022			2021			2023			2022			2021
Beginning balance	$	194		$	241		$	231		$	126		$	133		$	134
Originations		13			7			66			27			24			33
Purchases		350			—			—			—			—			—
Acquired in business combination		—			12			—			—			—			—
Amortization		(101	)		(66	)		(56	)		(30	)		(31	)		(34	)
		456			194			241			123			126			133
Valuation allowance		—			—			(24	)		—			—			—
Ending balance, net	$	456		$	194		$	217		$	123		$	126		$	133


	Residential Mortgage Loans				Commercial Mortgage Loans
(Dollars in millions)	2023		2022		2023		2022
Balances at period end
Loans serviced for others	$	40,021	$	22,365	$	24,157	$	22,166
Loans sub-serviced for others		115,321		96,027		3,873		3,841
Total loans serviced for others	$	155,342	$	118,392	$	28,030	$	26,007

During 2023, the Company completed a $350 million bulk purchase of residential mortgage loan servicing rights associated with $19.5 billion of residential real estate loans. In conjunction with the acquisition of People's United on April 1, 2022, the Company acquired servicing rights for residential real estate loans that had outstanding principal balances at that date of $1.1 billion. The fair value of such servicing rights at that date was $12 million.

The estimated fair value of capitalized residential mortgage loan servicing assets was approximately $611 million at December 31, 2023 and $336 million at December 31, 2022. The fair value of capitalized residential mortgage loan servicing assets was estimated using weighted-average discount rates of 11.45% and 12.29% at December 31, 2023 and 2022, respectively, and contemporaneous prepayment assumptions that vary by loan type. At December 31, 2023 and 2022, the discount rate represented a weighted-average OAS of 790 basis points over market implied forward SOFR and 881 basis points over market implied forward LIBOR, respectively. The estimated fair value of capitalized residential mortgage loan servicing rights may vary significantly in subsequent periods due to changing interest rates and the effect thereof on prepayment speeds. The estimated fair value of capitalized commercial mortgage loan servicing assets was approximately $193 million at December 31, 2023 and $156 million at December 31, 2022. A weighted-average discount rate of 14.43% was used to estimate the fair value of capitalized commercial mortgage loan servicing rights at December 31, 2023. Estimated servicing revenues and expenses used to value such servicing rights considered historical payment performance trends and current market interest rates. In general, the servicing agreements allow the Company to share in customer loan prepayment fees and thereby recover the remaining carrying value of the capitalized servicing rights associated with such loans. The Company's ability to realize the carrying value of capitalized commercial mortgage servicing rights is more dependent on the borrowers' abilities to repay the underlying loans than it is on prepayments. An 18% discount rate was used to estimate the value at December 31, 2022.

The key economic assumptions used to determine the fair value of significant portfolios of capitalized servicing rights at December 31, 2023 and the sensitivity of such value to changes in those assumptions are summarized in the table that follows. Those calculated sensitivities are hypothetical and actual changes in the fair value of capitalized servicing rights may differ significantly from the amounts presented herein. The effect of a variation in a particular assumption on the fair value of the servicing rights is calculated without changing any other assumption. In reality, changes in one factor may result in changes in another which may magnify or counteract the sensitivities. The changes in assumptions are presumed to be instantaneous.


(Dollars in millions)	Residential			Commercial
Weighted-average prepayment speeds		6.93	%
Impact on fair value of 10% adverse change	$	(16	)
Impact on fair value of 20% adverse change		(31	)
Weighted-average OAS		7.90	%
Impact on fair value of 10% adverse change	$	(18	)
Impact on fair value of 20% adverse change		(35	)
Weighted-average discount rate					14.43	%
Impact on fair value of 10% adverse change				$	(6	)
Impact on fair value of 20% adverse change					(12	)

- Definition

The entire disclosure for a transferor's continuing involvement in financial assets that it has transferred in a securitization or asset-backed financing arrangement, the nature of any restrictions on assets reported by an entity in its statement of financial position that relate to a transferred financial asset (including the carrying amounts of such assets), how servicing assets and servicing liabilities are reported, and (for securitization or asset-backed financing arrangements accounted for as sales) when a transferor has continuing involvement with the transferred financial assets and transfers of financial assets accounted for as secured borrowings, how the transfer of financial assets affects an entity's financial position, financial performance, and cash flows.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 860
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 860
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 860
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 210
-Name Accounting Standards Codification
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-Paragraph 1
-Subparagraph (SX 210.6-04(11))
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-URI https://asc.fasb.org//1943274/2147479617/946-210-S99-1

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 860
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 860
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Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 860
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-URI https://asc.fasb.org//1943274/2147481229/860-50-50-2

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 860
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Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 860
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-URI https://asc.fasb.org//1943274/2147481326/860-20-50-3

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 860
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
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Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 860
-SubTopic 20
-Name Accounting Standards Codification
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Reference 15: http://www.xbrl.org/2003/role/disclosureRef
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Reference 16: http://www.xbrl.org/2003/role/disclosureRef
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Reference 17: http://www.xbrl.org/2003/role/disclosureRef
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Reference 18: http://www.xbrl.org/2003/role/disclosureRef
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Reference 19: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 20: http://www.xbrl.org/2003/role/disclosureRef
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Reference 21: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Fair value measurements

12 Months Ended

Dec. 31, 2023

Fair Value Disclosures [Abstract]

Fair value measurements

21. Fair value measurements

GAAP permits an entity to choose to measure eligible financial instruments and other items at fair value. The Company has not made any fair value elections at December 31, 2023.

Pursuant to GAAP, fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. A three-level hierarchy exists in GAAP for fair value measurements based upon the inputs to the valuation of an asset or liability.

•

Level 1 — Valuation is based on quoted prices in active markets for identical assets and liabilities.

•

Level 2 — Valuation is determined from quoted prices for similar assets or liabilities in active markets, quoted prices for identical or similar instruments in markets that are not active or by model-based techniques in which all significant inputs are observable in the market.

•

Level 3 — Valuation is derived from model-based and other techniques in which at least one significant input is unobservable and which may be based on the Company’s own estimates about the assumptions that market participants would use to value the asset or liability.

When available, the Company attempts to use quoted market prices in active markets to determine fair value and classifies such items as Level 1 or Level 2. If quoted market prices in active markets are not available, fair value is often determined using model-based techniques incorporating various assumptions including interest rates, prepayment speeds and credit losses. Assets and liabilities valued using model-based techniques are classified as either Level 2 or Level 3, depending on the lowest level classification of an input that is considered significant to the overall valuation. The following is a description of the valuation methodologies used for the Company’s assets and liabilities that are measured on a recurring basis at estimated fair value.

Trading account

Mutual funds held in connection with deferred compensation and other arrangements have been classified as Level 1 valuations. Valuations of investments in municipal and other bonds can generally be obtained through reference to quoted prices in less active markets for the same or similar securities or through model-based techniques in which all significant inputs are observable and, therefore, such valuations have been classified as Level 2.

Available-for-sale investment securities and equity securities

The majority of the Company’s available-for-sale investment securities have been valued by reference to prices for similar securities or through model-based techniques in which all significant inputs are observable and, therefore, such valuations have been classified as Level 2. Certain investments in mutual funds and equity securities are actively traded and, therefore, have been classified as Level 1 valuations.

Real estate loans held for sale

The Company utilizes commitments to sell real estate loans to hedge the exposure to changes in fair value of real estate loans held for sale. The carrying value of hedged real estate loans held for sale includes changes in estimated fair value during the hedge period. Typically, the Company attempts to hedge real estate loans held for sale from the date of close through the sale date. The fair value of hedged real estate loans held for sale is generally calculated by reference to quoted prices in secondary markets for commitments to sell real estate loans with similar characteristics and, accordingly, such loans have been classified as a Level 2 valuation.

Commitments to originate real estate loans for sale and commitments to sell real estate loans

The Company enters into various commitments to originate real estate loans for sale and commitments to sell real estate loans. Such commitments are accounted for as derivative financial instruments and, therefore, are carried at estimated fair value on the Consolidated Balance Sheet. The estimated fair values of such commitments were generally calculated by reference to quoted prices in secondary markets for commitments to sell real estate loans to certain government-sponsored entities and other parties. The fair valuations of commitments to sell real estate loans generally result in a Level 2 classification. The estimated fair value of commitments to originate real estate loans for sale is adjusted to reflect the Company’s anticipated commitment expirations. The estimated commitment expirations are considered significant unobservable inputs contributing to the Level 3 classification of commitments to originate real estate loans for sale. Significant unobservable inputs used in the determination of estimated fair value of commitments to originate real estate loans for sale are included in the accompanying table of significant unobservable inputs to Level 3 measurements.

Interest rate swap agreements used for interest rate risk management

The Company utilizes interest rate swap agreements as part of the management of interest rate risk to modify the repricing characteristics of certain portions of its portfolios of earning assets and interest-bearing liabilities. The Company generally determines the fair value of its interest rate swap agreements using externally developed pricing models based on market observable inputs and, therefore, classifies such valuations as Level 2. The Company has considered counterparty credit risk in the valuation of its interest rate swap agreement assets and has considered its own credit risk in the valuation of its interest rate swap agreement liabilities.

Other non-hedging derivatives

Other non-hedging derivatives consist primarily of interest rate contracts and foreign exchange contracts with customers who require such services with offsetting positions with third parties to minimize the Company's risk with respect to such transactions. The Company generally determines the fair value of its other non-hedging derivative assets and liabilities using externally developed pricing models based on market observable inputs and, therefore, classifies such valuations as Level 2.

The following tables present assets and liabilities at December 31, 2023 and 2022 measured at estimated fair value on a recurring basis:


(Dollars in millions)	Fair Value Measurements		Level 1		Level 2		Level 3
December 31, 2023
Trading account	$	106	$	101	$	5	$	—
Investment securities available for sale:
U.S. Treasury and federal agencies		7,705		—		7,705		—
Mortgage-backed securities:
Government issued or guaranteed
Commercial		416		—		416		—
Residential		2,154		—		2,154		—
Other debt securities		165		—		165		—
		10,440		—		10,440		—
Equity securities		268		258		10		—
Real estate loans held for sale		379		—		379		—
Other assets (a)		324		—		309		15
Total assets	$	11,517	$	359	$	11,143	$	15
Other liabilities (a)	$	943	$	—	$	911	$	32
Total liabilities	$	943	$	—	$	911	$	32

December 31, 2022
Trading account	$	118	$	118	$	—	$	—
Investment securities available for sale:
U.S. Treasury and federal agencies		7,671		—		7,671		—
Mortgage-backed securities:
Government issued or guaranteed
Commercial		574		—		574		—
Residential		2,330		—		2,330		—
Other debt securities		174		—		174		—
		10,749		—		10,749		—
Equity securities		151		145		6		—
Real estate loans held for sale		162		—		162		—
Other assets (a)		435		—		435		—
Total assets	$	11,615	$	263	$	11,352	$	—
Other liabilities (a)	$	1,355	$	—	$	1,309	$	46
Total liabilities	$	1,355	$	—	$	1,309	$	46

(a)

The changes in Level 3 assets and liabilities measured at estimated fair value on a recurring basis during the years ended December 31, 2023, 2022 and 2021 were as follows:


	Other Assets and Other Liabilities
(Dollars in millions)	2023			2022			2021
Beginning balance	$	(46	)	$	6		$	43
Total gains (losses) realized/unrealized:
Included in earnings (a)		36			(34	)		126
Transfers out of Level 3 (b)		(7	)		(18	)		(163	)
Ending balance	$	(17	)	$	(46	)	$	6
Changes in net unrealized gains (losses) included in earnings related to instruments still held at period end (a)	$	15		$	(46	)	$	9

(a)

Reported as "mortgage banking revenues" in the Consolidated Statement of Income and includes the fair value of commitment issuances and expirations.

(b)

Transfers out of Level 3 consist of interest rate locks transferred to closed loans.

The Company is required, on a nonrecurring basis, to adjust the carrying value of certain assets or provide valuation allowances related to certain assets using fair value measurements. The more significant of those assets follow.

Loans

Loans are generally not recorded at fair value on a recurring basis. Periodically, the Company records nonrecurring adjustments to the carrying value of loans based on fair value measurements for partial charge-offs of the uncollectable portions of those loans. Nonrecurring adjustments also include certain impairment amounts for collateral-dependent loans when establishing the allowance for credit losses. Such amounts are generally based on the fair value of the underlying collateral supporting the loan and, as a result, the carrying value of the loan less the calculated valuation amount does not necessarily represent the fair value of the loan. Real estate collateral is typically valued using appraisals or other indications of value based on recent comparable sales of similar properties or assumptions generally observable in the marketplace and the related nonrecurring fair value measurement adjustments have generally been classified as Level 2, unless significant adjustments have been made to the valuation that are not readily observable by market participants. Non-real estate collateral supporting commercial and industrial loans generally consists of business assets such as receivables, inventory and equipment. Fair value estimations are typically determined by discounting recorded values of those assets to reflect estimated net realizable value considering specific borrower facts and circumstances and the experience of credit personnel in their dealings with similar borrower collateral liquidations. Such discounts were generally in the range of 10% to 90% with a weighted-average of 46% at December 31, 2023. As these discounts are not readily observable and are considered significant, the valuations have been classified as Level 3. Automobile collateral is typically valued by reference to independent pricing sources based on recent sales transactions of similar vehicles and the related nonrecurring fair value measurement adjustments have been classified as Level 2. Collateral values for other consumer installment loans are generally estimated based on historical recovery rates for similar types of loans, which at December 31, 2023 was 49%. As these recovery rates are not readily observable by market participants, such valuation adjustments have been classified as Level 3. Loans subject to nonrecurring fair value measurement were $923 million at December 31, 2023 ($234 million and $689 million of which were classified as Level 2 and Level 3, respectively), $853 million at December 31, 2022 ($329 million and $524 million of which were classified as Level 2 and Level 3, respectively), and $574 million at December 31, 2021 ($340 million and $234 million of which were classified as Level 2 and Level 3, respectively). Changes in fair value recognized during the years ended December 31, 2023, 2022 and 2021 for partial charge-offs of loans and loan impairment reserves on loans held by the

Company at the end of each of those years were decreases of $381 million, $191 million and $53 million, respectively.

Assets taken in foreclosure of defaulted loans

Assets taken in foreclosure of defaulted loans are primarily comprised of commercial and residential real property and are generally measured at the lower of cost or fair value less costs to sell. The fair value of the real property is generally determined using appraisals or other indications of value based on recent comparable sales of similar properties or assumptions generally observable in the marketplace, and the related nonrecurring fair value measurement adjustments have generally been classified as Level 2. Assets taken in foreclosure of defaulted loans subject to nonrecurring fair value measurement were not material at each of December 31, 2023 and 2022. Changes in fair value recognized during the years ended December 31, 2023, 2022 and 2021 for foreclosed assets held by the Company at the end of each of those years were not material.

Capitalized servicing rights

Capitalized servicing rights are initially measured at fair value in the Company’s Consolidated Balance Sheet. The Company utilizes the amortization method to subsequently measure its capitalized servicing assets. In accordance with GAAP, the Company must record impairment charges, on a nonrecurring basis, when the carrying value of certain strata exceed their estimated fair value. To estimate the fair value of servicing rights, the Company considers market prices for similar assets, if available, and the present value of expected future cash flows associated with the servicing rights calculated using assumptions that market participants would use in estimating future servicing income and expense. Such assumptions include estimates of the cost of servicing loans, loan default rates, an appropriate discount rate and prepayment speeds. For purposes of evaluating and measuring impairment of capitalized servicing rights, the Company stratifies such assets based on the predominant risk characteristics of the underlying financial instruments that are expected to have the most impact on projected prepayments, cost of servicing and other factors affecting future cash flows associated with the servicing rights. Such factors may include financial asset or loan type, note rate and term. The amount of impairment recognized is the amount by which the carrying value of the capitalized servicing rights for a stratum exceed estimated fair value. Impairment is recognized through a valuation allowance. The determination of fair value of capitalized servicing rights is considered a Level 3 valuation. Capitalized servicing rights related to residential mortgage loans required no valuation allowance at each of December 31, 2023 and 2022. Changes in fair value recognized for impairment of capitalized servicing rights related to residential mortgage loans were decreases in the valuation allowance of $24 million and $6 million in 2022 and 2021, respectively.

Significant unobservable inputs to Level 3 measurements

The following tables present quantitative information about significant unobservable inputs used in the fair value measurements for Level 3 assets and liabilities at December 31, 2023 and 2022:


(Dollars in millions)	Fair Value			Valuation Technique	Unobservable Inputs / Assumptions	Range (Weighted- Average)
December 31, 2023
Recurring fair value measurements
Net other assets (liabilities) (a)	$	(17	)	Discounted cash flow	Commitment expirations	0% - 99% (5%)

December 31, 2022
Recurring fair value measurements
Net other assets (liabilities) (a)	$	(46	)	Discounted cash flow	Commitment expirations	0% - 97% (3%)

(a)

Other Level 3 assets (liabilities) consist of commitments to originate real estate loans.

Sensitivity of fair value measurements to changes in unobservable inputs

An increase (decrease) in the estimate of expirations for commitments to originate real estate loans would generally result in a lower (higher) fair value measurement. Estimated commitment expirations are derived considering loan type, changes in interest rates and remaining length of time until closing.

Disclosures of fair value of financial instruments

The carrying amounts and estimated fair value for financial instrument assets (liabilities) are presented in the following tables:


	December 31, 2023
(Dollars in millions)	Carrying Amount			Estimated Fair Value			Level 1		Level 2			Level 3
Financial assets:
Cash and cash equivalents	$	1,731		$	1,731		$	1,668	$	63		$	—
Interest-bearing deposits at banks		28,069			28,069			—		28,069			—
Trading account		106			106			101		5			—
Investment securities		26,897			25,875			258		25,571			46
Loans and leases, net		131,939			129,138			—		7,240			121,898
Accrued interest receivable		786			786			—		786			—
Financial liabilities:
Noninterest-bearing deposits	$	(49,294	)	$	(49,294	)	$	—	$	(49,294	)	$	—
Savings and interest-checking deposits		(93,221	)		(93,221	)		—		(93,221	)		—
Time deposits		(20,759	)		(20,715	)		—		(20,715	)		—
Short-term borrowings		(5,316	)		(5,316	)		—		(5,316	)		—
Long-term borrowings		(8,201	)		(8,107	)		—		(8,107	)		—
Accrued interest payable		(482	)		(482	)		—		(482	)		—
Other financial instruments:
Commitments to originate real estate loans for sale	$	(17	)	$	(17	)	$	—	$	—		$	(17	)
Commitments to sell real estate loans		30			30			—		30			—
Other credit-related commitments		(154	)		(154	)		—		—			(154	)
Interest rate swap agreements used for interest rate risk management		10			10			—		10			—
Interest rate and foreign exchange contracts not designated as hedging instruments		(642	)		(642	)		—		(642	)		—


	December 31, 2022
(Dollars in millions)	Carrying Amount			Estimated Fair Value			Level 1		Level 2			Level 3
Financial assets:
Cash and cash equivalents	$	1,517		$	1,517		$	1,372	$	145		$	—
Interest-bearing deposits at banks		24,959			24,959			—		24,959			—
Federal funds sold		3			3			—		3			—
Trading account		118			118			118		—			—
Investment securities		25,211			24,056			145		23,860			51
Loans and leases, net		129,639			126,228			—		7,180			119,048
Accrued interest receivable		646			646			—		646			—
Financial liabilities:
Noninterest-bearing deposits	$	(65,502	)	$	(65,502	)	$	—	$	(65,502	)	$	—
Savings and interest-checking deposits		(87,911	)		(87,911	)		—		(87,911	)		—
Time deposits		(10,102	)		(10,143	)		—		(10,143	)		—
Short-term borrowings		(3,555	)		(3,555	)		—		(3,555	)		—
Long-term borrowings		(3,965	)		(3,926	)		—		(3,926	)		—
Accrued interest payable		(81	)		(81	)		—		(81	)		—
Other financial instruments:
Commitments to originate real estate loans for sale	$	(46	)	$	(46	)	$	—	$	—		$	(46	)
Commitments to sell real estate loans		54			54			—		54			—
Other credit-related commitments		(149	)		(149	)		—		—			(149	)
Interest rate swap agreements used for interest rate risk management		(8	)		(8	)		—		(8	)		—
Interest rate and foreign exchange contracts not designated as hedging instruments		(920	)		(920	)		—		(920	)		—

With the exception of marketable securities, certain off-balance sheet financial instruments and mortgage loans originated for sale, the Company’s financial instruments are not readily marketable and market prices do not exist. The Company, in attempting to comply with the provisions of GAAP that require disclosures of fair value of financial instruments, has not attempted to market its financial instruments to potential buyers, if any exist. Since negotiated prices in illiquid markets depend greatly upon the then present motivations of the buyer and seller, it is reasonable to assume that actual sales prices could vary widely from any estimate of fair value made without the benefit of negotiations. Additionally, changes in market interest rates can dramatically impact the value of financial instruments in a short period of time.

The Company does not believe that the estimated information presented herein is representative of the earnings power or value of the Company. The preceding analysis, which is inherently limited in depicting fair value, also does not consider any value associated with existing customer relationships nor the ability of the Company to create value through loan origination, deposit gathering or fee generating activities. Many of the estimates presented herein are based upon the use of highly subjective information and assumptions and, accordingly, the results may not be precise. Furthermore, because the disclosed fair value amounts were estimated as of the balance sheet date, the amounts actually realized or paid upon maturity or settlement of the various financial instruments could be significantly different.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Segment Information - Intersegment Activity Eliminated in Arriving at Consolidated Totals was Included in "All Other" Category (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Segment Reporting Information [Line Items]
Revenues	$ 9,643	$ 8,179	$ 5,992
Income taxes	878	620	596
Net Income (Loss)	2,741	1,992	1,859
Intersegment Activity Eliminated in Consolidated Totals [Member]
Segment Reporting Information [Line Items]
Revenues	(12)	(14)	(17)
Expenses	(2)	(2)	(3)
Income taxes	(3)	(3)	(4)
Net Income (Loss)	$ (7)	$ (9)	$ (10)

- Definition

Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

+ References + Details

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

+ Details

- Definition

Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

+ References

+ Details

Derivative financial instruments (Tables)

12 Months Ended

Dec. 31, 2023

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Information about Interest Rate Swap Agreements


			Average		Weighted-						Estimated
	Notional		Maturity		Average Rate						Fair Value
(Dollars in millions)	Amount		(In years)		Fixed			Variable			Gain (Loss) (a)
December 31, 2023
Fair value hedges:
Fixed rate long-term borrowings (b) (c)	$	3,000		5.8		3.45	%		5.62	%	$	(1	)
Cash flow hedges:
Interest payments on variable rate commercial real estate loans (b) (d)		23,977		1.7	3.45			5.36				11
Total	$	26,977		2.2							$	10
December 31, 2022
Fair value hedges:
Fixed rate long-term borrowings (b)	$	1,500		3.3		2.98	%		4.52	%	$	(1	)
Cash flow hedges:
Interest payments on variable rate commercial real estate loans (b) (e)		15,900		1.4	1.91			4.38				(7	)
Total	$	17,400		1.6							$	(8	)

(a)

(b)

Under the terms of these agreements, the Company receives settlement amounts at a fixed rate and pays at a variable rate.

(c)

Includes notional amount and terms of $1.0 billion of forward-starting interest rate swap agreements that become effective in 2025.

(d)

Includes notional amount and terms of $9.0 billion of forward-starting interest rate swap agreements that become effective in 2024.

(e)

Includes notional amount and terms of $4.7 billion of forward-starting interest rate swap agreements that became effective in 2023.

Notional Amount of Interest Rate Swap Agreements Outstanding Maturity

The notional amount of interest rate swap agreements entered into for risk management purposes that were outstanding at December 31, 2023 mature as follows:


(Dollars in millions)
Year ending December 31:
2024	$	3,158
2025		10,369
2026		10,450
2027		1,000
2028		1,000
2033		1,000
	$	26,977

Information about Fair Values of Derivative Instruments in Consolidated Balance Sheet

Information about the fair values of derivative instruments in the Company’s Consolidated Balance Sheet and Consolidated Statement of Income follows:


	Asset Derivatives				Liability Derivatives
	Fair Value				Fair Value
	December 31,		December 31,		December 31,		December 31,
(Dollars in millions)	2023		2022		2023		2022
Derivatives designated and qualifying as hedging instruments (a)
Interest rate swap agreements	$	12	$	1	$	2	$	9
Commitments to sell real estate loans		6		3		8		—
		18		4		10		9
Derivatives not designated and qualifying as hedging instruments (a)
Mortgage banking:
Commitments to originate real estate loans for sale		15		—		32		46
Commitments to sell real estate loans		35		51		3		—
		50		51		35		46
Other:
Interest rate contracts (b)		237		356		879		1,278
Foreign exchange and other option and futures contracts		19		24		19		22
		256		380		898		1,300
Total derivatives	$	324	$	435	$	943	$	1,355

(a)

Asset derivatives are reported in "accrued interest and other assets" and liability derivatives are reported in "accrued interest and other liabilities".


	Carrying Amount of the Hedged Item				Cumulative Amount of Fair Value Hedging Adjustment Increasing (Decreasing) the Carrying Amount of the Hedged Item
(Dollars in millions)	December 31, 2023		December 31, 2022		December 31, 2023			December 31, 2022
Location in the Consolidated Balance Sheet of the Hedged Items in Fair Value Hedges
Long-term borrowings	$	2,954	$	1,434	$	(44	)	$	(65	)

Information about Fair Values of Derivative Instruments in Consolidated Statement of Income


	Amount of Gain (Loss) Recognized
	Year ended December 31,
	2023					2022					2021
(Dollars in millions)	Derivative		Hedged Item			Derivative			Hedged Item		Derivative			Hedged Item
Derivatives in fair value hedging relationships
Interest rate swap agreements:
Fixed rate long-term borrowings (a)	$	22	$	(21	)	$	(109	)	$	109	$	(59	)	$	58
Derivatives not designated as hedging instruments
Interest rate contracts (b)	$	31				$	28				$	12
Foreign exchange and other option and futures contracts (b)		15					14					9
Total	$	46				$	42				$	21

(a)

Reported as an adjustment to "interest expense" in the Consolidated Statement of Income.

(b)

Reported as "trading account and other non-hedging derivative gains" in the Consolidated Statement of Income.

Loans and Leases - Summary of Payment Status of Loans Modified (Detail) $ in Millions	Dec. 31, 2023 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	$ 1,414
30-89 Days Past Due	123
Past Due 90 Days or More	49
Total	1,586
Commercial and Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	182
30-89 Days Past Due	7
Past Due 90 Days or More	9
Total	198
Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	618
30-89 Days Past Due	21
Past Due 90 Days or More	12
Total	651
Residential Builder and Developer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	71
Total	71
Other Commercial Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	440
30-89 Days Past Due	48
Total	488
Residential [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	93
30-89 Days Past Due	45
Past Due 90 Days or More	27
Total	165
Residential Limited Documentation [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	9
30-89 Days Past Due	2
Past Due 90 Days or More	1
Total	12
Home Equity Lines and Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	1
Total	$ 1

Pension Plans and Other Postretirement Benefits - Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Net gain	$ (125)	$ (84)
Net prior service cost		13
Amortization of prior service (cost) credit	2	2	$ 4
Amortization of actuarial (loss) gain	5	(18)	$ (88)
Total recognized in other comprehensive income, pre-tax	(118)	(87)
Pension Benefits [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Net gain	(120)	(62)
Amortization of prior service (cost) credit		(1)
Amortization of actuarial (loss) gain	2	(20)
Total recognized in other comprehensive income, pre-tax	118	(83)
Other Postretirement Benefits [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Net gain	(5)	(22)
Net prior service cost		13
Amortization of prior service (cost) credit	2	3
Amortization of actuarial (loss) gain	$ 3	2
Total recognized in other comprehensive income, pre-tax		$ (4)

Loans and Leases

12 Months Ended

Dec. 31, 2023

Receivables [Abstract]

Loans and leases

4. Loans and leases

Total loans and leases outstanding were comprised of the following:


	December 31,
(Dollars in millions)	2023			2022
Loans:
Commercial and industrial	$	55,000		$	49,775
Commercial real estate		33,065			35,364
Residential real estate		23,277			23,774
Consumer		20,780			20,579
Total loans		132,122			129,492
Leases:
Commercial		2,814			2,582
Total loans and leases		134,936			132,074
Less: unearned discount		(868	)		(510	)
Total loans and leases, net of unearned discount	$	134,068		$	131,564

One-to-four family residential mortgage loans held for sale were $190 million at December 31, 2023 and $32 million at December 31, 2022. Commercial real estate loans held for sale were $189 million at December 31, 2023 and $131 million at December 31, 2022.

The amount of foreclosed property held by the Company, predominantly consisting of residential real estate, was $39 million and $41 million at December 31, 2023 and 2022, respectively. There were $170 million and $201 million at December 31, 2023 and 2022, respectively, in loans secured by residential real estate that were in the process of foreclosure. Of all loans in the process of foreclosure at December 31, 2023, approximately 35% were government guaranteed.

Borrowings by directors and certain officers of M&T and its banking subsidiaries, and by associates of such persons, exclusive of loans aggregating less than $60,000, amounted to $116 million and $102 million at December 31, 2023 and 2022, respectively. During 2023, new borrowings by such persons amounted to $49 million (including any borrowings of new directors or officers that were outstanding at the time of their election) and repayments and other reductions (including reductions resulting from individuals ceasing to be directors or officers) were $35 million.

At December 31, 2023, approximately $13.4 billion of commercial and industrial loans, including leases, $16.4 billion of commercial real estate loans, $18.8 billion of one-to-four family residential real estate loans, $2.6 billion of home equity loans and lines of credit and $11.0 billion of other consumer loans were pledged to secure outstanding borrowings and available lines of credit from the FHLB and the FRB of New York as described in note 9. Additionally, at December 31, 2023, approximately $599 million of equipment finance loans and leases remain in a special purpose trust as collateral for certain asset-backed notes issued by M&T Bank in August 2023 as further described in notes 9 and 20.

A summary of current, past due and nonaccrual loans as of December 31, 2023 and 2022 follows:


(Dollars in millions)	Current		30-89 Days Past Due		Accruing Loans Past Due 90 Days or More		Nonaccrual		Total
December 31, 2023
Commercial and industrial	$	56,091	$	238	$	11	$	670	$	57,010
Real estate:
Commercial		24,072		311		25		869		25,277
Residential builder and developer		1,065		5		—		3		1,073
Other commercial construction		6,322		159		1		171		6,653
Residential		21,080		763		295		215		22,353
Residential — limited documentation		825		31		—		55		911
Consumer:
Home equity lines and loans		4,528		40		—		81		4,649
Recreational finance		9,935		87		—		36		10,058
Automobile		3,918		60		—		14		3,992
Other		2,003		30		7		52		2,092
Total	$	129,839	$	1,724	$	339	$	2,166	$	134,068

December 31, 2022
Commercial and industrial	$	50,842	$	498	$	76	$	504	$	51,920
Real estate:
Commercial		25,113		261		65		1,240		26,679
Residential builder and developer		1,305		9		—		1		1,315
Other commercial construction		6,937		240		—		125		7,302
Residential		21,492		596		345		272		22,705
Residential — limited documentation		951		22		—		78		1,051
Consumer:
Home equity lines and loans		4,891		31		—		85		5,007
Recreational finance		8,974		55		—		45		9,074
Automobile		4,393		44		—		40		4,477
Other		1,957		23		5		49		2,034
Total	$	126,855	$	1,779	$	491	$	2,439	$	131,564

Loan modifications

The table that follows summarizes the Company’s loan modification activities to borrowers experiencing financial difficulty for the year ended December 31, 2023:


	Amortized cost at December 31, 2023
(Dollars in millions)	Payment Deferral		Interest Rate Reduction		Other		Combination of Modification Types (a)		Total (b) (c)		Percent of Total Loan Class
Year Ended December 31, 2023
Commercial and industrial	$	179	$	18	$	—	$	1	$	198		.35	%
Real estate:
Commercial		610		—		—		41		651	2.57
Residential builder and developer		71		—		—		—		71	6.63
Other commercial construction		480		—		—		8		488	7.34
Residential		160		—		—		5		165		.74
Residential — limited documentation		11		—		—		1		12	1.25
Consumer:
Home equity lines and loans		—		—		—		1		1		.03
Recreational finance		—		—		—		—		—		—
Automobile		—		—		—		—		—		—
Other		—		—		—		—		—		—
Total	$	1,511	$	18	$	—	$	57	$	1,586		1.18	%

(a)

Predominantly payment deferrals combined with interest rate reductions.

(b)

Includes approximately $124 million of loans guaranteed by government-related entities (predominantly first lien residential mortgage loans).

(c)

Excludes unfunded commitments to extend credit totaling $128 million.

The financial effects of the modifications for the year ended December 31, 2023 include an increase in the weighted-average remaining term for commercial and industrial loans of 1.3 years, for commercial real estate loans, inclusive of residential builder and development loans and other commercial construction loans, of 1.1 years and for residential real estate loans, of 10.6 years.

Modified loans to borrowers experiencing financial difficulty are subject to the allowance for credit losses methodology described herein, including the use of models to inform credit loss estimates and, to the extent larger balance commercial and industrial and commercial real estate loans are in nonaccrual status, a loan-by-loan analysis of expected credit losses on those individual loans. The following table summarizes the payment status, at December 31, 2023, of loans that were modified during 2023.


	Payment status at December 31, 2023 (amortized cost)
(Dollars in millions)	Current		30-89 Days Past Due		Past Due 90 Days or More (a)		Total
Year Ended December 31, 2023
Commercial and industrial	$	182	$	7	$	9	$	198
Real estate:
Commercial		618		21		12		651
Residential builder and developer		71		—		—		71
Other commercial construction		440		48		—		488
Residential (b)		93		45		27		165
Residential — limited documentation		9		2		1		12
Consumer:
Home equity lines and loans		1		—		—		1
Recreational finance		—		—		—		—
Automobile		—		—		—		—
Other		—		—		—		—
Total	$	1,414	$	123	$	49	$	1,586

(a)

Predominantly loan modifications with payment deferrals.

(b)

Includes loans guaranteed by government-related entities classified as 30-89 days past due of $40 million and as past due 90 days or more of $24 million.

Prior to January 1, 2023, if a borrower was experiencing financial difficulty such that the Company did not expect to collect the contractual cash flows owed under the original loan agreement and a concession in loan terms was granted, the Company considered the loan modification as a troubled debt restructuring. The table that follows summarizes the Company’s loan modification activities that were considered troubled debt restructurings for the years ended December 31, 2022 and 2021. The table is not comparative to the preceding table. The Company no longer designates modified loans as a troubled debt restructuring in conjunction with the adoption of amended accounting guidance on January 1, 2023.


					Post-modification (a)
(Dollars in millions)	Number		Pre- modification Recorded Investment		Principal Deferral		Interest Rate Reduction		Other		Combination of Concession Types		Total
Year Ended December 31, 2022
Commercial and industrial		231	$	98	$	58	$	—	$	3	$	37	$	98
Real estate:
Commercial		12		25		9		—		—		16		25
Residential builder and developer		1		—		—		—		—		—		—
Other commercial construction		1		—		—		—		—		—		—
Residential		274		71		55		—		—		20		75
Residential — limited documentation		8		1		1		—		—		—		1
Consumer:
Home equity lines and loans		144		10		9		—		—		1		10
Recreational finance		729		28		28		—		—		—		28
Automobile		2,092		42		42		—		—		—		42
Other		149		1		1		—		—		—		1
Total		3,641	$	276	$	203	$	—	$	3	$	74	$	280

Year Ended December 31, 2021
Commercial and industrial		348	$	205	$	58	$	—	$	45	$	99	$	202
Real estate:
Commercial		35		184		57		—		27		98		182
Residential builder and developer		1		—		—		—		—		—		—
Other commercial construction		3		—		—		—		—		—		—
Residential		373		108		95		—		—		13		108
Residential — limited documentation		21		3		3		—		—		—		3
Consumer:
Home equity lines and loans		89		6		6		—		—		—		6
Recreational finance		281		10		10		—		—		—		10
Automobile		807		15		15		—		—		—		15
Other		362		3		3		—		—		—		3
Total		2,320	$	534	$	247	$	—	$	72	$	210	$	529

(a)

The Company’s loan and lease portfolio includes commercial lease financing receivables for construction and industrial equipment and machinery, railroad cars, commercial trucks and trailers, and aircraft. Certain leases contain payment schedules that are tied to variable interest rate indices. In general, early termination options are provided if the lessee is not in default, returns the leased equipment and pays an early termination fee. Additionally, options to purchase the underlying asset by the lessee are generally at the fair market value of the equipment. A summary of lease financing receivables follows.


	December 31,
(Dollars in millions)	2023			2022
Commercial leases:
Financing:
Lease payments receivable	$	2,431		$	2,175
Estimated residual value of leased assets		274			262
Unearned income		(248	)		(145	)
Investment in financing leases		2,457			2,292
Leveraged:
Lease payments receivable		57			71
Estimated residual value of leased assets		52			74
Unearned income		(15	)		(22	)
Investment in leveraged leases		94			123
Total investment in leases	$	2,551		$	2,415
Deferred taxes payable arising from leveraged leases	$	36		$	52

Included within the estimated residual value of leased assets at December 31, 2023 and 2022 were $96 million and $93 million, respectively, in residual value associated with financing leases that are guaranteed by the lessees or others.

At December 31, 2023, the minimum future lease payments to be received from lease financings were as follows:


(Dollars in millions)
Year ending December 31:
2024	$	823
2025		677
2026		468
2027		290
2028		136
Later years		94
	$	2,488

Earnings per common share

12 Months Ended

Dec. 31, 2023

Earnings Per Share [Abstract]

Earnings per common share

15. Earnings per common share

The computations of basic earnings per common share follow:


	Year Ended December 31,
(Dollars in millions, except per share, shares in thousands)	2023			2022			2021
Income available to common shareholders:
Net income	$	2,741		$	1,992		$	1,859
Less: Preferred stock dividends		(100	)		(97	)		(73	)
Net income available to common equity		2,641			1,895			1,786
Less: Income attributable to unvested stock-based compensation awards		(5	)		(4	)		(9	)
Net income available to common shareholders	$	2,636		$	1,891		$	1,777
Weighted-average shares outstanding:
Common shares outstanding (including common stock issuable) and unvested stock-based compensation awards		166,662			163,489			129,539
Less: Unvested stock-based compensation awards		(301	)		(315	)		(890	)
Weighted-average shares outstanding		166,361			163,174			128,649

Basic earnings per common share	$	15.85		$	11.59		$	13.81

The computations of diluted earnings per common share follow:


	Year Ended December 31,
(Dollars in millions, except per share, shares in thousands)	2023			2022			2021
Net income available to common equity	$	2,641		$	1,895		$	1,786
Less: Income attributable to unvested stock-based compensation awards		(5	)		(4	)		(9	)
Net income available to common shareholders	$	2,636		$	1,891		$	1,777
Adjusted weighted-average shares outstanding:
Common shares outstanding (including common stock issuable) and unvested stock-based compensation awards		166,662			163,489			129,539
Less: Unvested stock-based compensation awards		(301	)		(315	)		(890	)
Plus: Incremental shares from assumed conversion of stock-based compensation awards and warrants to purchase common stock		641			856			163
Adjusted weighted-average shares outstanding		167,002			164,030			128,812

Diluted earnings per common share	$	15.79		$	11.53		$	13.80

GAAP defines unvested share-based awards that contain nonforfeitable rights to dividends or dividend equivalents (whether paid or unpaid) as participating securities that shall be included in the computation of earnings per common share pursuant to the two-class method. The Company has issued stock-based compensation awards in the form of restricted stock and restricted stock units, which, in accordance with GAAP, are considered participating securities.

Stock-based compensation awards to purchase common stock of M&T representing common shares of 1,834,000 in 2023, 453,000 in 2022 and 461,000 in 2021 were not included in the computations of diluted earnings per common share because the effect on those years would have been antidilutive.

Commitments and contingencies (Tables)

12 Months Ended

Dec. 31, 2023

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingent Liabilities Outstanding

The following table presents the Company’s significant commitments. Certain of these commitments are not included in the Company’s Consolidated Balance Sheet.


	December 31,		December 31,
(Dollars in millions)	2023		2022
Commitments to extend credit:
Commercial and industrial	$	28,566	$	27,471
Commercial real estate loans to be sold		916		349
Other commercial real estate		5,019		5,084
Residential real estate loans to be sold		163		31
Other residential real estate		331		505
Home equity lines of credit		8,109		8,262
Credit cards		5,578		5,465
Other		413		382
Standby letters of credit		2,289		2,377
Commercial letters of credit		62		65
Financial guarantees and indemnification contracts		4,036		4,022
Commitments to sell real estate loans		1,400		533

Borrowings - Amounts and Interest Rates of Short-term Borrowings (Detail) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Schedule Of Borrowings [Line Items]
Weighted-average interest rate	5.23%	4.24%
Repurchase agreements and short term borrowings	$ 5,316	$ 3,555
Repurchase Agreements [Member]
Schedule Of Borrowings [Line Items]
Weighted-average interest rate	3.26%	1.01%
Repurchase Agreements	$ 316	$ 355
FHLB Advances [Member]
Schedule Of Borrowings [Line Items]
Weighted-average interest rate	5.35%	4.59%
Other Short-Term Borrowings	$ 5,000	$ 3,200

- Definition

Amount, after the effects of master netting arrangements, of funds outstanding borrowed in the form of a security repurchase agreement between the entity and another party for the sale and repurchase of identical or substantially the same securities at a date certain for a specified price. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 320
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SX 210.12-12A(Column A)(Footnote 2))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480032/946-320-S99-2

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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-Section S99
-Paragraph 1
-Subparagraph (SX 210.12-12(Column A)(Footnote 2))
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-Section S99
-Paragraph 1
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-URI https://asc.fasb.org//1943274/2147479853/942-210-S99-1

+ Details

Recent accounting developments

12 Months Ended

Dec. 31, 2023

Accounting Changes and Error Corrections [Abstract]

Recent accounting developments

27. Recent accounting developments

The following table provides a description of accounting standards that were adopted by the Company in 2023 as well as standards that are not effective that could have an impact to M&T’s consolidated financial statements upon adoption.


Standard	Description	Required date of adoption	Effect on consolidated financial statements
Standards Adopted in 2023
Fair Value Hedging of Multiple Hedge Layers under Portfolio Layer Method	The amendments allow multiple hedged layers to be designated for a single closed portfolio of financial assets or one or more beneficial interests secured by a portfolio of financial instruments. If multiple hedged layers are designated, the amendments require an analysis to be performed to support the expectation that the aggregate amount of the hedged layers is anticipated to be outstanding for the designated hedge periods. Only closed portfolios may be hedged under the portfolio layer method (that is, no assets can be added to the closed portfolio once established), however designating new hedging relationships and dedesignating existing hedging relationships associated with the closed portfolio any time after the closed portfolio is established is permitted.	January 1, 2023	The Company did not have any designated hedging relationships under the portfolio layer method in 2023 and, therefore, the adoption had no impact on its consolidated financial statements.
Accounting for Troubled Debt Restructurings and Expansion of Vintage Disclosures Applicable to Credit Losses	The amendments (1) eliminate the accounting guidance for troubled debt restructurings and require enhanced disclosure for certain loan refinancings by creditors when a borrower is experiencing financial difficulty and (2) require disclosure of current period gross write-offs by year of origination for financing receivables and net investments in leases within credit loss disclosures.	January 1, 2023	The Company adopted the amended guidance effective January 1, 2023 using a prospective transition method and is no longer required to identify troubled debt restructurings and apply specialized accounting to such loans. The Company has complied with the modified disclosure requirements in notes 4 and 5.
Standards Not Yet Adopted as of December 31, 2023
Accounting for Investments in Tax Credit Structures Using the Proportional Amortization Method	The amendments permit an election to account for tax equity investments, regardless of the tax credit program from which the income tax credits are received, using the proportional amortization method if certain conditions are met. Under the proportional amortization method, the initial cost of the investment is amortized in proportion to the income tax credits and other income tax benefits received and the net amortization and income tax credits and other income tax benefits are recognized in the income statement as a component of income tax expense (benefit).	January 1, 2024 Early adoption permitted	The Company adopted the amended guidance effective January 1, 2024 using a modified retrospective transition. The guidance did not have a material impact on the Company’s consolidated financial statements.

- Definition

The entire disclosure for change in accounting principle. Includes, but is not limited to, nature, reason, and method of adopting amendment to accounting standards or other change in accounting principle.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
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+ Details

Income Taxes - Reconciliation of Beginning and Ending Amount of Unrecognized Tax Benefits (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Federal, State and Local Tax [Member]
Reconciliation Of Unrecognized Tax Benefits [Line Items]
Beginning Balance	$ 30	$ 38	$ 49
Increases as a result of tax positions taken in prior years	5
Decreases as a result of tax positions taken in prior years	(13)	(11)	(11)
Unrecognized tax benefits assumed in a business combination		3
Ending Balance	22	30	38
Accrued Interest [Member]
Reconciliation Of Unrecognized Tax Benefits [Line Items]
Beginning Balance	8	8	8
Increases as a result of tax positions taken in prior years	1	3	3
Decreases as a result of tax positions taken in prior years	(3)	(4)	(3)
Unrecognized tax benefits assumed in a business combination		1
Ending Balance	6	8	8
Unrecognized Income Tax Benefits [Member]
Reconciliation Of Unrecognized Tax Benefits [Line Items]
Beginning Balance	38	45	56
Increases as a result of tax positions taken in prior years	6	3	3
Decreases as a result of tax positions taken in prior years	(16)	(15)	(14)
Unrecognized tax benefits assumed in a business combination		5
Ending Balance	28	$ 38	$ 45
Less: Federal, state and local income tax benefits	(6)
Net unrecognized tax benefits that, if recognized, would impact the effective income tax rate	$ 22

Premises and Equipment - Summary of Minimum Lease Payments Under Noncancelable Operating Leases (Detail) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Property Plant And Equipment Capitalized Interest Costs [Abstract]
2024	$ 162
2025	145
2026	122
2027	101
2028	75
Later years	208
Total lease payments	813
Less: imputed interest	96
Operating lease liabilities	$ 717	$ 709

Revenue from Contracts with Customers - Additional Information (Detail) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Disaggregation Of Revenue [Line Items]
Uncollected amounts receivable	$ 68	$ 74
Accrued interest and other liabilities [Member]
Disaggregation Of Revenue [Line Items]
Deferred revenue	$ 54	$ 48

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References + Details

Capitalized servicing assets (Tables)

12 Months Ended

Dec. 31, 2023

Transfers and Servicing [Abstract]

Servicing Asset at Amortized Cost

Changes in capitalized servicing assets were as follows:


	Year Ended December 31,
	Residential Mortgage Loans									Commercial Mortgage Loans
(Dollars in millions)	2023			2022			2021			2023			2022			2021
Beginning balance	$	194		$	241		$	231		$	126		$	133		$	134
Originations		13			7			66			27			24			33
Purchases		350			—			—			—			—			—
Acquired in business combination		—			12			—			—			—			—
Amortization		(101	)		(66	)		(56	)		(30	)		(31	)		(34	)
		456			194			241			123			126			133
Valuation allowance		—			—			(24	)		—			—			—
Ending balance, net	$	456		$	194		$	217		$	123		$	126		$	133


	Residential Mortgage Loans				Commercial Mortgage Loans
(Dollars in millions)	2023		2022		2023		2022
Balances at period end
Loans serviced for others	$	40,021	$	22,365	$	24,157	$	22,166
Loans sub-serviced for others		115,321		96,027		3,873		3,841
Total loans serviced for others	$	155,342	$	118,392	$	28,030	$	26,007

Economic Assumptions Used to Determine Fair Value of Capitalized Servicing Rights and Sensitivity of Value to Changes in Assumptions


(Dollars in millions)	Residential			Commercial
Weighted-average prepayment speeds		6.93	%
Impact on fair value of 10% adverse change	$	(16	)
Impact on fair value of 20% adverse change		(31	)
Weighted-average OAS		7.90	%
Impact on fair value of 10% adverse change	$	(18	)
Impact on fair value of 20% adverse change		(35	)
Weighted-average discount rate					14.43	%
Impact on fair value of 10% adverse change				$	(6	)
Impact on fair value of 20% adverse change					(12	)

Significant accounting policies (Policies)	12 Months Ended
Significant accounting policies (Policies)	Dec. 31, 2023
Accounting Policies [Abstract]
Consolidation	Consolidation The consolidated financial statements include M&T and all of its subsidiaries. All significant intercompany accounts and transactions of consolidated subsidiaries have been eliminated in consolidation. The financial statements of M&T included in note 26 report investments in subsidiaries under the equity method. Information about some limited purpose entities that are affiliates of the Company but are not included in the consolidated financial statements appears in note 20.
Consolidated Statement of Cash Flows	Consolidated Statement of Cash Flows For purposes of this statement, cash and due from banks and federal funds sold are considered cash and cash equivalents.
Securities purchased under agreements to resell and securities sold under agreements to repurchase	Securities purchased under agreements to resell and securities sold under agreements to repurchase Securities purchased under agreements to resell and securities sold under agreements to repurchase are treated as collateralized financing transactions and are recorded at amounts equal to the cash or other consideration exchanged. It is generally the Company’s policy to take possession of collateral pledged to secure agreements to resell.
Trading account	Trading account Financial instruments used for trading purposes are stated at fair value. Realized gains and losses and unrealized changes in fair value of financial instruments utilized in trading activities are included in “trading account and other non-hedging derivative gains” in the Consolidated Statement of Income.
Investment securities	Investment securities Investments in debt securities are classified as held to maturity and stated at amortized cost when management has the positive intent and ability to hold such securities to maturity. Investments in other debt securities are classified as available for sale and stated at estimated fair value with unrealized changes in fair value included in “accumulated other comprehensive income (loss), net.” Amortization of premiums and accretion of discounts for investment securities available for sale and held to maturity are included in interest income. Investments in equity securities having readily determinable fair values are stated at fair value and unrealized changes in fair value are included in earnings. Investments in equity securities that do not have readily determinable fair values are stated at cost minus impairment, if any, plus or minus changes resulting from observable price changes in orderly transactions for the identical or a similar investment of the same issuer. Other equity securities include stock of the FRB of New York and the FHLB of New York. GAAP requires an allowance for credit losses be deducted from the amortized cost basis of financial assets, including investment securities held to maturity, to present the net carrying value at the amount that is expected to be collected over the contractual term. In cases where fair value of an available-for-sale debt security is less than its amortized cost basis and the Company does not intend to sell the available-for-sale debt security and it is not more likely than not that the Company will be required to sell the security before recovery of the amortized cost basis, the difference between the fair value and the amortized cost basis is separated into (a) the amount representing the credit loss and (b) the amount related to all other factors. The amount related to the credit loss is recognized as an allowance for credit losses while the amount related to other factors is recognized in other comprehensive income, net of applicable income taxes. If the Company intends to sell the security or it is more likely than not to be required to sell the security before recovery of the amortized cost basis, the security is written down to fair value with the entire amount recognized in earnings. Subsequently, the Company accounts for the debt security as if the security had been purchased on the measurement date of the write down at an amortized cost basis equal to the previous amortized cost basis less the amount of the write down recognized in earnings. Realized gains and losses on the sales of investment securities are determined using the specific identification method.
Loans and leases	Loans and leases The Company’s accounting methods for loans depend on whether the loans were originated or acquired by the Company. Originated loans and leases Loan fees and certain direct loan origination costs are deferred and recognized as an interest yield adjustment over the life of the loan. Net deferred fees have been included in unearned discount as a reduction of loans outstanding. Interest income on loans is accrued on a level yield method. Loans are placed on nonaccrual status and previously accrued interest thereon is charged against income when it is probable that the Company will be unable to collect all amounts according to the contractual terms of the loan agreement or when principal or interest is delinquent 90 days. Certain loans greater than 90 days delinquent continue to accrue interest if they are well-secured and in the process of collection. Loans less than 90 days delinquent are deemed to have an insignificant delay in payment and generally continue to accrue interest. Interest received on loans placed on nonaccrual status is generally applied to reduce the carrying value of the loan or, if principal is considered fully collectable, recognized as interest income. Nonaccrual commercial and industrial loans and commercial real estate loans are returned to accrual status when borrowers have demonstrated an ability to repay their loans and there are no delinquent principal and interest payments. Loans secured by residential real estate are returned to accrual status when they are deemed to have an insignificant delay in payments of 90 days or less. Consumer loans not secured by residential real estate are returned to accrual status when all past due principal and interest payments have been paid by the borrower. Loan balances are charged-off when it becomes evident that such balances are not fully collectable. For commercial and industrial loans and commercial real estate loans, charge-offs are recognized after an assessment by credit personnel of the capacity and willingness of the borrower to repay, the estimated value of any collateral, and any other potential sources of repayment. A charge-off is recognized when, after such assessment, it becomes evident that the loan balance is not fully collectable. For loans secured by residential real estate, the excess of the loan balances over the net realizable value of the property collateralizing the loan is charged-off when the loan becomes 150 days delinquent. Consumer loans are generally charged-off when the loans are 91 to 180 days past due, depending on whether the loan is collateralized and the status of repossession activities with respect to such collateral. During the normal course of business, the Company modifies loans to maximize recovery efforts from borrowers experiencing financial difficulty. Such loan modifications typically include payment deferrals and interest rate reductions but may also include other modified terms. Those modified loans may be considered nonaccrual if the Company does not expect to collect the contractual cash flows owed under the loan agreement. On January 1, 2023, the Company adopted amended guidance that eliminated the accounting guidance for troubled debt restructurings while expanding disclosure requirements for certain loan refinancings and restructurings by creditors when a borrower is experiencing financial difficulty. The amended guidance also requires disclosure of current period gross charge-offs by year of origination. Prior to January 1, 2023, if the borrower was experiencing financial difficulty such that the Company did not expect to collect the contractual cash flows owed under the original loan agreement and a concession in loan terms was granted, the Company considered the loan modification as a troubled debt restructuring and such loans were classified as either nonaccrual or renegotiated loans. Commitments to sell real estate loans are utilized by the Company to hedge the exposure to changes in fair value of real estate loans held for sale. The carrying value of hedged real estate loans held for sale recorded in the Consolidated Balance Sheet includes changes in estimated fair value during the hedge period, typically from the date of close through the sale date. Valuation adjustments made on these loans and commitments are included in “mortgage banking revenues” in the Consolidated Statement of Income. Acquired loans and leases Expected credit losses for PCD loans are initially recognized as an allowance for credit losses and are added to the purchase price to determine the amortized cost basis of the loans. Any non-credit discount or premium resulting from acquiring such loans is recognized as an adjustment to interest income over the remaining lives of the loans. Subsequent changes in the amount of expected credit losses on such loans are recognized in the allowance for credit losses in the same manner as originated loans. For all other acquired loans, the difference between the fair value and outstanding principal balance of the loans is recognized as an adjustment to interest income over the lives of those loans. Those loans are then accounted for in a manner that is similar to originated loans.
Allowance for credit losses	Allowance for credit losses The allowance for credit losses is deducted from the amortized cost basis of financial assets to present the net carrying value at the amount that is expected to be collected over the contractual term of the asset considering relevant information about past events, current conditions, and reasonable and supportable forecasts that affect the collectability of the reported amount. In estimating expected losses in the loan and lease portfolio, borrower-specific financial data and macro-economic assumptions are utilized to project losses over a reasonable and supportable forecast period. Assumptions and judgment are applied to measure amounts and timing of expected future cash flows, collateral values and other factors used to determine the borrowers’ abilities to repay obligations. Subsequent to the forecast period, the Company utilizes longer-term historical loss experience to estimate losses over the remaining contractual life of the loans.
Assets taken in foreclosure of defaulted loans	Assets taken in foreclosure of defaulted loans Assets taken in foreclosure of defaulted loans are primarily comprised of commercial and residential real property and are included in “accrued interest and other assets” in the Consolidated Balance Sheet. An in-substance repossession or foreclosure occurs and a creditor is considered to have received physical possession of real estate property collateralizing a mortgage loan upon either (i) the creditor obtaining legal title to the real estate property upon completion of a foreclosure or (ii) the borrower conveying all interest in the real estate property to the creditor to satisfy that loan through completion of a deed in lieu of foreclosure or through a similar legal agreement. Upon acquisition of assets taken in satisfaction of a defaulted loan, the excess of the remaining loan balance over the asset’s estimated fair value less costs to sell is charged-off against the allowance for credit losses. Subsequent declines in value of the assets are recognized as “other costs of operations” in the Consolidated Statement of Income.
Premises and equipment	Premises and equipment Premises and equipment are stated at cost less accumulated depreciation. Depreciation expense is computed principally using the straight-line method over the estimated useful lives of the assets.
Capitalized servicing rights	Capitalized servicing rights Capitalized servicing assets are included in “accrued interest and other assets” in the Consolidated Balance Sheet. Separately recognized servicing assets are initially measured at fair value. The Company uses the amortization method to subsequently measure servicing assets. Under that method, capitalized servicing assets are charged to expense in proportion to and over the period of estimated net servicing income. To estimate the fair value of servicing rights, the Company considers market prices for similar assets and the present value of expected future cash flows associated with the servicing rights calculated using assumptions that market participants would use in estimating future servicing income and expense. Such assumptions include estimates of the cost of servicing loans, loan default rates, an appropriate discount rate, and prepayment speeds. For purposes of evaluating and measuring impairment of capitalized servicing rights, the Company stratifies such assets based on the predominant risk characteristics of the underlying financial instruments that are expected to have the most impact on projected prepayments, cost of servicing and other factors affecting future cash flows associated with the servicing rights. Such factors may include financial asset or loan type, note rate and term. The amount of impairment recognized is the amount by which the carrying value of the capitalized servicing rights for a stratum exceeds estimated fair value. Impairment is recognized through a valuation allowance.
Sales and securitizations of financial assets	Sales and securitizations of financial assets Transfers of financial assets for which the Company has surrendered control of the financial assets are accounted for as sales. Interests in a sale of financial assets that continue to be held by the Company, including servicing rights, are initially measured at fair value. The fair values of retained debt securities are generally determined through reference to independent pricing information. The fair values of retained servicing rights and any other retained interests are determined based on the present value of expected future cash flows associated with those interests and by reference to market prices for similar assets. Securitization structures and other financial vehicles oftentimes require the use of special-purpose trusts that are considered variable interest entities. A variable interest entity is included in the consolidated financial statements if the Company has the power to direct the activities that most significantly impact the variable interest entity’s economic performance and has the obligation to absorb losses or the right to receive benefits of the variable interest entity that could potentially be significant to that entity. The recognition or de-recognition in the Company’s consolidated financial statements of assets and liabilities held by variable interest entities is subject to the interpretation and application of complex accounting pronouncements or interpretations that require management to estimate and assess the relative significance of the Company’s financial interests in those entities and the degree to which the Company can influence the most important activities of the entities.
Goodwill and core deposit and other intangible assets	Goodwill and core deposit and other intangible assets Goodwill represents the excess of the cost of an acquired entity over the fair value of the identifiable net assets acquired. Goodwill is not amortized, but rather is tested for impairment at least annually at the reporting unit level, which is either at the same level or one level below an operating segment. Other acquired intangible assets with finite lives, such as core deposit intangibles, are initially recorded at estimated fair value and are amortized over their estimated lives. Core deposit and other intangible assets are generally amortized using accelerated methods over estimated useful lives, which are generally three to seven years. The Company periodically assesses whether events or changes in circumstances indicate that the carrying amounts of core deposit and other intangible assets may be impaired.
Derivative financial instruments	Derivative financial instruments The Company accounts for derivative financial instruments at fair value. If certain conditions are met, a derivative may be specifically designated as (i) a hedge of the exposure to changes in the fair value of a recognized asset or liability or an unrecognized firm commitment, (ii) a hedge of the exposure to variable cash flows of a forecasted transaction or (iii) a hedge of the foreign currency exposure of a net investment in a foreign operation, an unrecognized firm commitment, an available-for-sale security, or a foreign currency denominated forecasted transaction. The Company utilizes interest rate swap agreements as part of the management of interest rate risk to modify the repricing characteristics of certain portions of its portfolios of earning assets and interest-bearing liabilities. For such agreements, amounts receivable or payable are recognized as accrued under the terms of the agreement and the net differential is recorded as an adjustment to interest income or expense of the related asset or liability. Interest rate swap agreements may be designated as either fair value hedges or cash flow hedges. In a fair value hedge, the fair values of the interest rate swap agreements and changes in the fair values of the hedged items are recorded in the Company’s Consolidated Balance Sheet with the corresponding gain or loss recognized in current earnings. The difference between changes in the fair values of interest rate swap agreements and the hedged items represents hedge ineffectiveness and is recorded in the same income statement line item that is used to present the earnings effect of the hedged item in the Consolidated Statement of Income. In a cash flow hedge, the derivative’s unrealized gain or loss is initially recorded as a component of other comprehensive income and subsequently reclassified into earnings when the forecasted transaction affects earnings. The Company utilizes commitments to sell real estate loans to hedge the exposure to changes in the fair value of real estate loans held for sale. Commitments to originate real estate loans to be held for sale and commitments to sell real estate loans are generally recorded in the Consolidated Balance Sheet at estimated fair value. Valuation adjustments made on these commitments are included in “mortgage banking revenues” in the Consolidated Statement of Income. Derivative instruments not related to mortgage banking activities, including financial futures commitments and interest rate swap agreements, that do not satisfy the hedge accounting requirements are recorded at fair value and are generally classified as other assets or other liabilities with resultant changes in fair value being recognized in “trading account and other non-hedging derivative gains” in the Consolidated Statement of Income.
Revenue from contracts with customers	Revenue from contracts with customers A significant amount of the Company’s revenues are derived from net interest income on financial assets and liabilities, mortgage banking revenues, trading account and other non-hedging derivative gains, investment securities gains, loan and letter of credit fees, income from bank-owned life insurance, and certain other revenues that are generally excluded from the scope of accounting guidance for revenue from contracts with customers. For other noninterest income revenue streams, the Company generally recognizes the expected amount of consideration as revenue when the performance obligations related to the services under the terms of a contract are satisfied. The Company’s contracts generally do not contain terms that necessitate significant judgment to determine the amount of revenue to recognize.
Stock-based compensation	Stock-based compensation Compensation expense is recognized over the vesting period of stock-based awards based on estimated grant date value, except that the recognition of compensation costs is accelerated for stock-based awards granted to retirement-eligible employees and employees who will become retirement-eligible prior to full vesting of the award because the Company’s incentive compensation plan allows for vesting at the time an employee retires.
Income taxes	Income taxes Deferred tax assets and liabilities are recognized for the future tax effects attributable to differences between the financial statement value of existing assets and liabilities and their respective tax bases and carryforwards. Deferred tax assets and liabilities are measured using enacted tax rates and laws. The Company evaluates uncertain tax positions using the two-step process required by GAAP. The first step requires a determination of whether it is more likely than not that a tax position will be sustained upon examination, including resolution of any related appeals or litigation processes, based on the technical merits of the position. Under the second step, a tax position that meets the more-likely-than-not recognition threshold is measured at the largest amount of benefit that is greater than fifty percent likely of being realized upon ultimate settlement. The Company accounts for its investments in qualified affordable housing projects using the proportional amortization method. Under that method, the Company amortizes the initial cost of the investment in proportion to the tax credits and other tax benefits received and recognizes the net investment performance in the income statement as a component of income tax expense.
Earnings per common share	Earnings per common share Basic earnings per common share exclude dilution and are computed by dividing income available to common shareholders by the weighted-average number of common shares outstanding (exclusive of shares represented by the unvested portion of restricted stock and restricted stock unit grants) and common shares issuable under deferred compensation arrangements during the period. Diluted earnings per common share reflect shares represented by the unvested portion of restricted stock and restricted stock unit grants and the potential dilution that could occur if securities or other contracts to issue common stock were exercised or converted into common stock or resulted in the issuance of common stock that then shared in earnings. Proceeds assumed to have been received on such exercise or conversion are assumed to be used to purchase shares of M&T common stock at the average market price during the period, as required by the “treasury stock method” of accounting. GAAP requires that unvested share-based payment awards that contain nonforfeitable rights to dividends or dividend equivalents (whether paid or unpaid) shall be considered participating securities and shall be included in the computation of earnings per common share pursuant to the two-class method. The Company has issued stock-based compensation awards in the form of restricted stock and restricted stock units that contain such rights and, accordingly, the Company’s earnings per common share are calculated using the two-class method.
Treasury stock	Treasury stock Repurchases of shares of M&T common stock are recorded at cost as a reduction of shareholders’ equity. Reissuances of shares of treasury stock are recorded at average cost.

Shareholders' Equity - Additional Information (Detail) - $ / shares	Dec. 31, 2023	Dec. 31, 2022
Equity [Abstract]
Preferred stock, shares authorized	20,000,000	20,000,000
Preferred stock, par value	$ 1.00	$ 1.00

Derivative Financial Instruments - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Derivative [Line Items]
Notional amounts of derivative contracts entered into for trading account purposes	$ 26,977	$ 17,400
Unrealized gain recognized in other comprehensive income related to cash flow hedges	203
Aggregate fair value of derivative financial instruments in asset position	179	314
Collateral relating to net asset positions	179	312
Clearinghouse Credit Facilities [Member]
Derivative [Line Items]
Amount of initial margin posted	129	205
Interest Income [Member]
Derivative [Line Items]
Changes in Cash Flow Hedges Derivative Instruments At Fair Value Net	250	36
Interest Rate Swap Agreements [Member]
Derivative [Line Items]
Increase decrease in net interest income due to interest rate swap agreements	$ 302	$ 26	$ 287
Derivative Instrument, Gain (Loss) Reclassified from AOCI into Income, Effective Portion, Statement of Income or Comprehensive Income [Extensible Enumeration]	Interest and Dividend Income, Operating	Interest and Dividend Income, Operating	Interest and Dividend Income, Operating
Interest Rate Swap Agreements [Member] \| Maturity Period 2024 [Member]
Derivative [Line Items]
Unrealized gain recognized in other comprehensive income related to cash flow hedges	$ 5
Interest Rate Swap Agreements [Member] \| Maturity Period 2025 [Member]
Derivative [Line Items]
Unrealized gain recognized in other comprehensive income related to cash flow hedges	211
Interest Rate Swap Agreements [Member] \| Maturity Period 2026 [Member]
Derivative [Line Items]
Unrealized gain recognized in other comprehensive income related to cash flow hedges	13
Interest Rate Contracts [Member]
Derivative [Line Items]
Notional amounts of derivative contracts entered into for trading account purposes	44,400	$ 45,100
Foreign Currency and Other Option and Futures Contracts [Member]
Derivative [Line Items]
Notional amounts of derivative contracts entered into for trading account purposes	$ 1,500	$ 1,700

Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Loss Contingencies [Line Items]
Commitments to extend credit to commercial customers	$ 12,300	$ 11,700
Maximum credit risk for recourse associated with loans sold under Federal National Mortgage Association Delegated Underwriting and Servicing program	3,900	$ 3,900
Minimum [Member]
Loss Contingencies [Line Items]
Range of reasonably possible losses	0
Maximum [Member]
Loss Contingencies [Line Items]
Range of reasonably possible losses	$ 25

Investment Securities - Investment Securities in Continuous Unrealized Loss Position (Detail) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Estimated fair value, Less than 12 months	$ 460	$ 9,670
Available For Sale Securities Continuous Unrealized Losses Position Less Than Twelve Months Aggregate Losses	4	378
Estimated fair value, 12 months or more	9,917	944
Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or More Aggregate Losses	247	67
Held to maturity, Estimated fair value, Less than 12 months	1,551	10,559
Held To Maturity Securities Continuous Unrealized Loss Position Less Than12 Months Aggregate Losses	23	885
Held to maturity, Estimated fair value, 12 months or more	11,844	1,355
Held To Maturity Securities Continuous Unrealized Loss Position12 Months Or Longer Aggregate Losses	1,012	280
Total investment securities, fair value less than 12 months	2,011	20,229
Investment Securities Continuous Unrealized Loss Position Less Than Twelve Months Aggregate Losses	27	1,263
Total of investment securities, fair value, 12 Months or More	21,761	2,299
Investment Securities Continuous Unrealized Loss Position Twelve Months or Longer Aggregate Losses	1,259	347
U.S. Treasury and Federal Agencies [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Estimated fair value, Less than 12 months	229	6,707
Available For Sale Securities Continuous Unrealized Losses Position Less Than Twelve Months Aggregate Losses	1	184
Estimated fair value, 12 months or more	7,474	842
Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or More Aggregate Losses	112	59
Held to maturity, Estimated fair value, Less than 12 months	50	1,008
Held To Maturity Securities Continuous Unrealized Loss Position Less Than12 Months Aggregate Losses		46
Held to maturity, Estimated fair value, 12 months or more	924
Held To Maturity Securities Continuous Unrealized Loss Position12 Months Or Longer Aggregate Losses	31
Commercial [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Estimated fair value, Less than 12 months	74	574
Available For Sale Securities Continuous Unrealized Losses Position Less Than Twelve Months Aggregate Losses	1	21
Estimated fair value, 12 months or more	330
Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or More Aggregate Losses	8
Held to maturity, Estimated fair value, Less than 12 months	328	809
Held To Maturity Securities Continuous Unrealized Loss Position Less Than12 Months Aggregate Losses	9	103
Held to maturity, Estimated fair value, 12 months or more	1,575
Held To Maturity Securities Continuous Unrealized Loss Position12 Months Or Longer Aggregate Losses	121
Residential [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Estimated fair value, Less than 12 months	151	2,296
Available For Sale Securities Continuous Unrealized Losses Position Less Than Twelve Months Aggregate Losses	2	169
Estimated fair value, 12 months or more	1,959	29
Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or More Aggregate Losses	116	2
Held to maturity, Estimated fair value, Less than 12 months	955	6,293
Held To Maturity Securities Continuous Unrealized Loss Position Less Than12 Months Aggregate Losses	11	619
Held to maturity, Estimated fair value, 12 months or more	7,139	1,319
Held To Maturity Securities Continuous Unrealized Loss Position12 Months Or Longer Aggregate Losses	791	272
Obligations of States and Political Subdivisions [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Held to maturity, Estimated fair value, Less than 12 months	218	2,449
Held To Maturity Securities Continuous Unrealized Loss Position Less Than12 Months Aggregate Losses	3	117
Held to maturity, Estimated fair value, 12 months or more	2,172
Held To Maturity Securities Continuous Unrealized Loss Position12 Months Or Longer Aggregate Losses	64
Other Debt Securities [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Estimated fair value, Less than 12 months	6	93
Available For Sale Securities Continuous Unrealized Losses Position Less Than Twelve Months Aggregate Losses		4
Estimated fair value, 12 months or more	154	73
Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or More Aggregate Losses	11	6
Privately Issued [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Held to maturity, Estimated fair value, 12 months or more	34	36
Held To Maturity Securities Continuous Unrealized Loss Position12 Months Or Longer Aggregate Losses	$ 5	$ 8

Parent Company Financial Statements - Condensed Balance Sheet (Detail) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Investments in consolidated subsidiaries
Total assets	$ 208,264	$ 200,730
Liabilities
Long-term borrowings	8,201	3,965
Total liabilities	181,307	175,412
Shareholders’ equity	26,957	25,318	$ 17,903	$ 16,187
Total liabilities and shareholders’ equity	208,264	200,730
Parent Company [Member]
Assets
Cash in subsidiary bank	176	130
Due from consolidated bank subsidiaries
Money-market savings	3,223	1,690
Current income tax receivable	5	4
Total due from consolidated bank subsidiaries	3,228	1,694
Investments in consolidated subsidiaries
Banks	26,290	25,005
Other	391	380
Investments in trust preferred entities (note 20)	22	22
Other assets	100	93
Total assets	30,207	27,324
Liabilities
Accrued expenses and other liabilities	152	172
Long-term borrowings	3,098	1,834
Total liabilities	3,250	2,006
Shareholders’ equity	26,957	25,318
Total liabilities and shareholders’ equity	$ 30,207	$ 27,324

Loans and Leases - Summary of Lease Financing Receivables (Detail) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Financing:
Lease payments receivable	$ 2,431	$ 2,175
Estimated residual value of leased assets	274	262
Unearned income	(248)	(145)
Investment in financing leases	2,457	2,292
Leveraged:
Lease payments receivable	57	71
Estimated residual value of leased assets	52	74
Unearned income	(15)	(22)
Investment in leveraged leases	94	123
Total investment in leases	2,551	2,415
Deferred taxes payable arising from leveraged leases	$ 36	$ 52

Pension Plans and Other Postretirement Benefits - Defined Benefit Plan Estimated Future Benefit Payments (Detail) $ in Millions	Dec. 31, 2023 USD ($)
Pension Benefits [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
2024	$ 150
2025	154
2026	157
2027	160
2028	164
2029 through 2033	838
Other Postretirement Benefits [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
2024	4
2025	4
2026	4
2027	4
2028	4
2029 through 2033	$ 19

Derivative Financial Instruments - Information about Fair Values of Derivative Instruments in Consolidated Statement of Income (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives not designated as hedging instruments, Derivatives	$ 46	$ 42	$ 21
Interest Rate Swap Agreements [Member] \| Fixed Rate Long-Term Borrowings [Member] \| Derivatives Designated and Qualifying as Hedging Instruments [Member] \| Fair Value Hedges [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives in fair value hedging relationships, Derivatives	$ 22	$ (109)	$ (59)
Derivative, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Noninterest Expense	Other Noninterest Expense	Other Noninterest Expense
Derivatives in fair value hedging relationships, Hedged item	$ (21)	$ 109	$ 58
Interest Rate Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives not designated as hedging instruments, Derivatives	31	28	12
Foreign Exchange and Other Option and Futures Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives not designated as hedging instruments, Derivatives	$ 15	$ 14	$ 9

Derivative Financial Instruments - Information about Hedged Items Included in Consolidated Balance Sheet (Detail) - Long-term Borrowings [Member] - Derivatives Designated and Qualifying as Hedging Instruments [Member] - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Carrying Amount [Member]
Derivatives, Fair Value [Line Items]
Hedged Item	$ 2,954	$ 1,434
Cumulative Amount of Fair Value Hedging Adjustment Increasing (Decreasing) the Carrying Amount [Member]
Derivatives, Fair Value [Line Items]
Hedged Item	$ (44)	$ (65)

Revenue from Contracts with Customers - Additional Information (Detail1)	Dec. 31, 2023
Maximum [Member] \| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2022-01-01
Disaggregation Of Revenue [Line Items]
Period of satisfaction of contract with customer	1 year

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References + Details

Acquisition and Divestitures - Summary of Identifiable Assets Acquired, Liabilities Assumed and Preferred Stock Exchanged as of Acquisition (Parenthetical) (Details)	Apr. 01, 2022 shares
Peoples United Financial Inc [Member]
Business Acquisition [Line Items]
Common shares issued, Shares	50,325,004

Acquisition and divestitures

12 Months Ended

Dec. 31, 2023

Business Combinations [Abstract]

Acquisition and divestitures

2. Acquisition and divestitures

Acquisition

On April 1, 2022, M&T completed the acquisition of People's United. Through subsidiaries, People's United provided commercial banking, retail banking and wealth management services to individual, corporate and municipal customers through a network of branches located in Connecticut, southeastern New York, Massachusetts, Vermont, New Hampshire and Maine. Following the merger, People's United Bank, National Association, a national banking association and a wholly owned subsidiary of People's United, merged with and into M&T Bank, the principal banking subsidiary of M&T, with M&T Bank as the surviving entity. The results of operations acquired from People's United have been included in the Company's financial results since April 1, 2022.

Pursuant to the terms of the merger agreement dated February 22, 2021, People’s United shareholders received consideration valued at .118 of an M&T common share in exchange for each common share of People’s United. The purchase price totaled approximately $8.4 billion (with the price based on M&T’s closing price of $164.66 per share as of April 1, 2022). M&T issued 50,325,004 common shares in completing the transaction. Additionally, People’s United outstanding preferred stock was converted into new shares of Series H Preferred Stock of M&T. The acquisition of People's United expanded the Company's geographical footprint and management expects the Company will benefit from greater geographical diversity and the advantages of scale associated with a larger company.

The People’s United transaction has been accounted for using the acquisition method of accounting and, accordingly, assets acquired, liabilities assumed and preferred stock converted were recorded at estimated fair value on the acquisition date. The consideration paid for People’s United common equity and the preliminary amounts of identifiable assets acquired, liabilities assumed and preferred stock converted as of the acquisition date follows.


(Dollars in millions)
Consideration:
Common stock issued (50,325,004 shares)	$	8,286
Common stock awards converted		105
Cash		2
Total consideration		8,393

Net assets acquired:
Identifiable assets:
Cash and due from banks		396
Interest-bearing deposits at banks		9,193
Investment securities		11,575
Loans and leases		35,841
Core deposit and other intangible assets		261
Other assets		2,979
Total identifiable assets acquired		60,245
Liabilities and preferred stock:
Deposits		52,968
Borrowings		1,389
Other liabilities		1,142
Total liabilities assumed		55,499
Preferred stock		261
Total liabilities and preferred stock		55,760
Net assets acquired		4,485
Goodwill	$	3,908

The following is a description of the methodologies used to estimate the fair values of the significant assets acquired, liabilities assumed and preferred stock converted at the acquisition date:

Cash and due from banks and interest-bearing deposits in banks: Given the short-term nature of these assets, the carrying amount was determined to be a reasonable estimate of fair value.

Investment securities: Investment securities have been determined using quoted market prices, if available. If quoted market prices were not available, investment securities were valued by reference to quoted prices for similar securities or through model-based techniques.

Loans and leases: The fair values of loans and leases were generally based on a discounted cash flow methodology that considered market interest rates, expected credit losses, prepayment assumptions and other market factors for loans with similar characteristics including loan type, collateral, fixed or variable interest rate and credit risk characteristics. Expected credit losses were determined based on credit characteristics and other factors such as default and recovery rates of similar products.

Core deposit and other intangible assets: The core deposit intangible asset represents the value of certain customer deposit relationships. The fair value of the core deposit intangible asset was based on a discounted cash flow methodology that considered expected customer attrition rates, costs associated with maintaining the deposit relationships and alternative funding costs. Other intangible assets were also valued using expected and contractual cash flows.

Deposits: The fair value of deposits with no maturity date was determined to be the amount payable on demand at the acquisition date. The fair value of time deposits was determined by discounting contractual cash flows using market interest rates for instruments with like remaining maturities.

Borrowings: The fair value of borrowings was determined using quoted market prices for the instrument, if available. If quoted market prices for the instrument were not available, similar instruments with quoted market prices were referenced.

Preferred stock: The fair value of preferred stock converted was determined using quoted market prices.

GAAP requires loans and leases obtained through an acquisition that have experienced a more-than-insignificant deterioration in credit quality since origination be considered PCD. The Company considered several factors in the determination of PCD loans, including loan grades assigned to acquired commercial loans and leases and commercial real estate loans utilizing the Company's loan grading system and delinquency status and history for acquired loans backed by residential real estate. For PCD loans and leases, the initial estimate of expected credit losses of $99 million was established through an adjustment to increase both the initial carrying value and allowance for credit losses. GAAP also provides that an allowance for credit losses on loans acquired, but not classified as PCD, also be recognized above and beyond the impact of forecasted losses used in determining fair value. Accordingly, the Company recorded $242 million of provision for credit losses for non-PCD acquired loans and leases at the acquisition date. The following table reconciles the unpaid principal balance to the fair value of loans and leases at April 1, 2022:


(Dollars in millions)	PCD				Non-PCD
Unpaid principal balance	$	3,411		(a)	$	32,896
Allowance for credit losses at acquisition		(99	)	(a)		—
Other discount		(107	)			(260	)	(b)
Fair value	$	3,205			$	32,636

(a)

The unpaid principal balance and allowance for credit losses at acquisition is net of charge-offs of $33 million recognized on the PCD loans.

(b)

Includes approximately $242 million of principal balances not expected to be collected.

In connection with the acquisition, the Company recorded approximately $3.9 billion of goodwill, which represents the excess of the purchase price over the fair value of the net assets acquired, and $261 million of core deposit and other intangible assets. The core deposit and other intangible assets are being amortized over periods of three to seven years. Information regarding the allocation of goodwill to the Company’s reportable segments, as well as the carrying amounts and amortization of core deposit and other intangible assets, is provided in note 8.

Due to the integration of People's United operating systems and activities with those of the Company, the Company's ability to report on the former operations of People's United is inherently limited. The Company estimates that included in the Consolidated Statement of Income from the acquisition date through December 31, 2022 are total revenues of approximately $1.6 billion and net income of approximately $165 million related to the acquisition of People's United.

The following table presents certain pro forma information as if People’s United had been acquired on January 1, 2021. These results combine the historical results of People’s United into the Company’s Consolidated Statement of Income and, while adjustments were made for the estimated impact of certain fair valuation adjustments and other acquisition-related activity, they are not indicative of what would have occurred had the acquisition taken place as indicated. For example, merger-related expenses noted below are included in the periods where such expenses were incurred. Additionally, the Company expects to achieve operating cost savings and other business synergies as a result of the acquisition which are not reflected in the pro forma amounts that follow:


	Pro forma (Unaudited)
(Dollars in millions)	2022		2021
Total revenues (a)	$	8,631	$	8,076
Net income		2,158		2,391

(a)

Represents the total of net interest income and other income.

In connection with the People’s United acquisition, the Company incurred merger-related expenses related to systems conversions and other costs of integrating and conforming acquired operations with and into the Company. Those expenses consisted largely of professional services, temporary help fees and other costs associated with actual or planned systems conversions and/or integration of operations and the introduction of the Company to its new customers; costs related to termination of existing contractual arrangements for various services; initial marketing and promotion expenses designed to introduce M&T Bank to its new customers; severance (for former People’s United employees); and other costs of completing the transaction and commencing operations in new markets and offices. The Company did not incur any People's United merger-related expenses during 2023. A summary of merger-related expenses included in the Consolidated Statement of Income in 2022 and 2021 follows.


(Dollars in millions)	2022		2021
Salaries and employee benefits	$	102	$	—
Equipment and net occupancy		7		—
Outside data processing software		5		1
Professional and other services		72		37
Advertising and marketing		9		1
Other cost of operations		143		5
Other expense	$	338	$	44

The Company also recognized a $242 million provision for credit losses on acquired loans that were not deemed to be PCD on April 1, 2022. GAAP requires that acquired loans be recorded at estimated fair value, which includes the use of interest rate and expected credit loss assumptions to forecast estimated cash flows. GAAP also provides that an allowance for credit losses on loans acquired, but not classified as PCD also be recognized above and beyond the impact of forecasted losses used in determining the fair value of acquired loans. Accordingly, the Company recorded a $242 million provision for credit losses related to such loans obtained in the People's United transaction.

Divestitures

On April 29, 2023, Wilmington Trust, N.A., a wholly owned subsidiary of M&T, sold its CIT business to a private equity firm. The transaction resulted in a pre-tax gain of $225 million ($157 million after-tax effect) that has been included in "other revenues from operations" in the Consolidated Statement of Income for the year ended December 31, 2023. Prior to the sale, the CIT business contributed $60 million, $165 million and $151 million to trust income in 2023, 2022 and 2021, respectively. After considering expenses, the results of operations from the CIT business were not material to the Company's consolidated results of operations in any of those years.

On October 31, 2022, M&T Bank sold MTIA, a wholly owned insurance agency subsidiary of M&T Bank, to Arthur J. Gallagher & Co. The Company recognized a pre-tax gain on the sale of $136 million ($98 million after-tax effect) that has been included in "other revenue from operations" in the Consolidated Statement of Income for the year ended December 31, 2022. MTIA had assets of $18 million and shareholders' equity of $6 million at the time of the divestiture. Prior to the sale, MTIA recorded revenues of $34 million in 2022 and $37 million in 2021. After considering expenses, the results of operations from MTIA were not material to the Company's consolidated results of operations in each of 2022 and 2021.

Capitalized Servicing Assets - Economic Assumptions Used to Determine Fair Value of Capitalized Servicing Rights and Sensitivity of Value to Changes in Assumptions (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Sensitivity Analysis of Fair Value of Interests Continued to be Held by Transferor, Servicing Assets or Liabilities, Impact of Adverse Change in Assumption [Line Items]
Weighted-average discount rate	14.43%	18.00%
Residential Mortgage Loans [Member]
Sensitivity Analysis of Fair Value of Interests Continued to be Held by Transferor, Servicing Assets or Liabilities, Impact of Adverse Change in Assumption [Line Items]
Weighted-average prepayment speeds	6.93%
Impact on fair value of 10% adverse change	$ (16)
Impact on fair value of 20% adverse change	$ (31)
Weighted-average OAS	7.90%
Impact on fair value of 10% adverse change	$ (18)
Impact on fair value of 20% adverse change	$ (35)
Weighted-average discount rate	11.45%	12.29%
Commercial Mortgage Loans [Member]
Sensitivity Analysis of Fair Value of Interests Continued to be Held by Transferor, Servicing Assets or Liabilities, Impact of Adverse Change in Assumption [Line Items]
Weighted-average discount rate	14.43%
Impact on fair value of 10% adverse change	$ (6)
Impact on fair value of 20% adverse change	$ (12)

Allowance for Credit Losses - Loan and Leases Considered Nonaccrual and Interest Income Recognized on Loans (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Jan. 01, 2023	Jan. 01, 2022	Jan. 01, 2021	Dec. 31, 2020
Financing Receivable, Impaired [Line Items]
Amortized Cost with Allowance	$ 986	$ 997	$ 789
Amortized Cost without Allowance	1,180	1,442	1,271
Total	2,166	2,439	2,060
Amortized Cost				$ 2,439	$ 2,060	$ 1,893
Interest Income Recognized	78	77	59
Commercial and Industrial [Member]
Financing Receivable, Impaired [Line Items]
Amortized Cost with Allowance	397	212					$ 153
Amortized Cost without Allowance	273	292					218
Total	670	504					371
Amortized Cost				504	371	433
Interest Income Recognized	22	26	23
Commercial [Member]
Financing Receivable, Impaired [Line Items]
Amortized Cost with Allowance	288	366	199
Amortized Cost without Allowance	581	874	720
Total	869	1,240	919
Amortized Cost				1,240	919	650
Interest Income Recognized	29	14	5
Residential Builder and Developer [Member]
Financing Receivable, Impaired [Line Items]
Amortized Cost with Allowance	3	1	1
Amortized Cost without Allowance			2
Total	3	1	3
Amortized Cost				1	3	1
Interest Income Recognized		2	1
Other Commercial Construction [Member]
Financing Receivable, Impaired [Line Items]
Amortized Cost with Allowance	71	59					30
Amortized Cost without Allowance	100	66					81
Total	171	125					111
Amortized Cost				125	111	114
Interest Income Recognized	2	4	1
Residential [Member]
Financing Receivable, Impaired [Line Items]
Amortized Cost with Allowance	81	147					198
Amortized Cost without Allowance	134	125					158
Total	215	272					356
Amortized Cost				272	356	366
Interest Income Recognized	15	25	24
Residential Limited Documentation [Member]
Financing Receivable, Impaired [Line Items]
Amortized Cost with Allowance	19	48					80
Amortized Cost without Allowance	36	30					43
Total	55	78					123
Amortized Cost				78	123	147
Interest Income Recognized	2	1
Home Equity Lines and Loans [Member]
Financing Receivable, Impaired [Line Items]
Amortized Cost with Allowance	42	43	32
Amortized Cost without Allowance	39	42	38
Total	81	85	70
Amortized Cost				85	70	79
Interest Income Recognized	7	4	4
Recreational Finance [Member]
Financing Receivable, Impaired [Line Items]
Amortized Cost with Allowance	24	37	22
Amortized Cost without Allowance	12	8	6
Total	36	45	28
Amortized Cost				45	28	26
Interest Income Recognized	1	1	$ 1
Automobile [Member]
Financing Receivable, Impaired [Line Items]
Amortized Cost with Allowance	9	35					29
Amortized Cost without Allowance	5	5					5
Total	14	40					34
Amortized Cost				40	34	39
Other [Member]
Financing Receivable, Impaired [Line Items]
Amortized Cost with Allowance	52	49					45
Total	$ 52	$ 49					$ 45
Amortized Cost				$ 49	$ 45	$ 38

Shareholders' equity

12 Months Ended

Dec. 31, 2023

Equity [Abstract]

Shareholders' equity

10. Shareholders’ equity

M&T is authorized to issue 20,000,000 shares of preferred stock with a $1.00 par value per share. Preferred shares outstanding rank senior to common shares both as to dividends and liquidation preference, but have no general voting rights. Issued and outstanding preferred stock of M&T at each of December 31, 2023 and 2022 is presented below:


(Dollars in millions)	Shares Issued and Outstanding		Carrying Value
Series E (a)
Fixed-to-Floating Rate Non-cumulative Perpetual Preferred Stock $1,000 liquidation preference per share		350,000	$	350
Series F (b)
Fixed-to-Floating Rate Non-cumulative Perpetual Preferred Stock $10,000 liquidation preference per share		50,000		500
Series G (c)
Fixed-Rate Reset Non-cumulative Perpetual Preferred Stock $10,000 liquidation preference per share		40,000		400
Series H (d)
Fixed-to-Floating Rate Non-cumulative Perpetual Preferred Stock $25 liquidation preference per share		10,000,000		261
Series I (e)
Fixed-Rate Reset Non-cumulative Perpetual Preferred Stock $10,000 liquidation preference per share		50,000		500

(a)

(b)

(c)

(d)

(e)

- Definition

The entire disclosure for equity.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (h)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 14
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-14

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 235
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481062/946-235-50-2

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 235
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481062/946-235-50-2

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 505
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481004/946-505-50-6

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480237/815-40-50-6

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480008/505-10-S99-1

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(e)(1))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480678/235-10-S99-1

Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 505
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org//505/tableOfContent

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (g)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (i)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 14
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-14

Reference 15: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 14
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-14

Reference 16: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 16
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-16

Reference 17: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 18
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-18

Reference 18: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 18
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-18

Reference 19: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 18
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-18

+ Details

Pension Plans and Other Postretirement Benefits - Data Relating to Funding Position of Defined Benefit Plans (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Change in plan assets:
Fair value of plan assets at beginning of year	$ 2,938
Fair value of plan assets at end of year	3,141	$ 2,938
Pension Benefits [Member]
Change in benefit obligation:
Benefit obligation at beginning of year	2,379	2,420
Service cost	11	18	$ 20
Interest cost	$ 115	$ 82	$ 62
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Excluding Service Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Noninterest Expense	Other Noninterest Expense	Other Noninterest Expense
Actuarial (gain) loss	$ 13	$ (636)
Business combinations		633
Benefits paid	(149)	(138)
Benefit obligation at end of year	2,369	2,379	$ 2,420
Change in plan assets:
Fair value of plan assets at beginning of year	2,942	2,596
Actual return on plan assets	334	(386)
Employer contributions	18	14
Business combinations		856
Benefits paid	(149)	(138)
Fair value of plan assets at end of year	3,145	2,942	2,596
Funded status	776	563
Prepaid asset recognized in the Consolidated Balance Sheet	922	715
Accrued liability recognized in the Consolidated Balance Sheet	(146)	(152)
Net accrued asset (liability) recognized in the Consolidated Balance Sheet	776	563
Net loss (gain)	191	309
Pre-tax adjustment to accumulated other comprehensive income	191	309
Taxes	(49)	(80)
Net adjustment to accumulated other comprehensive income	142	229
Other Postretirement Benefits [Member]
Change in benefit obligation:
Benefit obligation at beginning of year	60	52
Service cost	2	3	1
Interest cost	$ 3	$ 2	$ 1
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Excluding Service Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Noninterest Expense	Other Noninterest Expense	Other Noninterest Expense
Plan participants’ contributions	$ 1	$ 2
Actuarial (gain) loss	(5)	(22)
Plan amendment		13
Business combinations		15
Medicare Part D reimbursement		1
Benefits paid	(4)	(6)
Benefit obligation at end of year	57	60	$ 52
Change in plan assets:
Employer contributions	3	3
Plan participants’ contributions	1	2
Medicare Part D reimbursement		1
Benefits paid	(4)	(6)
Funded status	(57)	(60)
Accrued liability recognized in the Consolidated Balance Sheet	(57)	(60)
Net accrued asset (liability) recognized in the Consolidated Balance Sheet	(57)	(60)
Net loss (gain)	(37)	(35)
Net prior service cost (credit)	1	(1)
Pre-tax adjustment to accumulated other comprehensive income	(36)	(36)
Taxes	9	9
Net adjustment to accumulated other comprehensive income	$ (27)	$ (27)

Income Taxes - Schedule of Income Taxes Expenses Benefit Reconciliation (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Income taxes at statutory federal income tax rate	$ 760	$ 548	$ 516
Increase (decrease) in taxes:
Tax-exempt income	(51)	(37)	(21)
State and local income taxes, net of federal income tax effect	161	110	101
Qualified affordable housing project tax benefits, net	(26)	(22)	(15)
Other	34	21	15
Income taxes	$ 878	$ 620	$ 596

- Definition

Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

+ References + Details

Goodwill and Other Intangible Assets - Summary of Estimated Amortization Expense (Detail) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Finite-Lived Intangible Assets, Net, Amortization Expense, Rolling Maturity [Abstract]
2024	$ 53
2025	38
2026	27
2027	18
2028	9
Later years	2
Net Carrying Amount	$ 147	$ 209

Stock-based compensation plans

12 Months Ended

Dec. 31, 2023

Share-Based Payment Arrangement [Abstract]

Stock-based compensation plans

12. Stock-based compensation plans

Stock-based compensation expense was $118 million in 2023, $111 million in 2022 and $85 million in 2021. The Company recognized income tax benefits related to stock-based compensation of $24 million in 2023, $26 million in 2022 and $16 million in 2021.

The Company’s equity incentive compensation plan allows for the issuance of various forms of stock-based compensation, including stock options, restricted stock and restricted stock units, including performance-based awards. At December 31, 2023 and 2022, respectively, there were 4,218,093 and 1,650,696 shares available for future grant under the Company’s equity incentive compensation plan.

Stock awards

Stock awards granted to employees are comprised of restricted stock and restricted stock units. Stock awards generally vest over three years. The Company may issue shares from treasury stock to the extent available or issue new shares. There were no restricted shares issued in 2023, 2022 or 2021. The number of restricted stock units issued was 752,534 in 2023, 548,926 in 2022 and 636,956 in 2021, with a weighted-average grant date fair value of $116 million, $93 million and $84 million, respectively. Unrecognized compensation expense associated with restricted stock and restricted stock units, inclusive of those awards assumed in the acquisition of People's United, was $42 million as of December 31, 2023 and is expected to be recognized over a weighted-average period of approximately one year.

A summary of restricted stock and restricted stock unit activity follows:


	Restricted Stock Units Outstanding			Weighted- Average Grant Price		Restricted Stock Outstanding			Weighted- Average Grant Price
Unvested at January 1, 2023		1,167,582		$	156.23		75,006		$	164.65
Granted		752,534			153.86		—			—
Vested		(543,987	)		156.97		(35,777	)		164.66
Cancelled		(45,851	)		159.73		(7,514	)		164.66
Unvested at December 31, 2023		1,330,278		$	154.46		31,715		$	164.63

Stock option awards

Stock options granted to employees generally vest over three years and are exercisable over terms not exceeding ten years and one day. The Company granted 179,551, 138,825 and 178,441 stock options in 2023, 2022 and 2021, respectively. The weighted-average grant date fair value of options granted was $9 million in 2023, $6 million in 2022 and $5 million in 2021. The Company used an option pricing model to estimate the grant date present value of stock options granted.

A summary of stock option activity follows:


				Weighted-Average
	Stock Options Outstanding			Exercise Price		Life (In Years)		Aggregate Intrinsic Value (In millions)
Outstanding at January 1, 2023		2,340,062		$	148.78
Granted		179,551			156.00
Exercised		(262,837	)		122.45
Expired		(58,112	)		155.87
Outstanding at December 31, 2023		2,198,664		$	152.33		5.6	$	6
Exercisable at December 31, 2023		1,807,515		$	151.67		5.0	$	5

For 2023, 2022 and 2021 M&T received $32 million, $37 million and $305 thousand, respectively, in cash from the exercise of stock options. The intrinsic value of stock options exercised and the related tax benefit realized by the Company were not material in any of those three years. As of December 31, 2023, the amount of unrecognized compensation cost related to non-vested stock options was not material. The total grant date fair value of stock options vested during 2023, 2022 and 2021 was not material. Upon the exercise of stock options, the Company may issue shares from treasury stock to the extent available or issue new shares.

Stock purchase plan

The stock purchase plan provides eligible employees of the Company with the right to purchase shares of M&T common stock at a discount through accumulated payroll deductions. In connection with the employee stock purchase plan, shares of M&T common stock issued were 90,575 in 2023, 75,232 in 2022 and 95,147 in 2021. As of December 31, 2023, there were 1,972,627 shares available for issuance under the plan. M&T received cash for shares purchased through the employee stock purchase plan of $13 million in 2023 and $11 million in each of 2022 and 2021. Compensation expense recognized for the stock purchase plan was not material in 2023, 2022 or 2021.

Deferred bonus plan

The Company provided a deferred bonus plan pursuant to which eligible employees could elect to defer all or a portion of their annual incentive compensation awards and allocate such awards to several investment options, including M&T common stock. The deferred bonus plan was frozen effective January 1, 2010 and did not allow any additional deferrals after that date. Participants could elect the timing of distributions from the plan. Such distributions are payable in cash with the exception of balances allocated to M&T common stock which are distributable in the form of M&T common stock. Shares of M&T common stock distributable pursuant to the terms of the deferred bonus plan were 10,238 and 11,725 at December 31, 2023 and 2022, respectively. The obligation to issue shares is included in “common stock issuable” in the Consolidated Balance Sheet.

Directors’ stock compensation programs

The Company maintains compensation programs for members of the Company’s boards of directors and its regional director advisory councils that provides for a portion of their compensation to be received in shares or restricted stock units. In 2023 and 2022, 27,027 and 22,068 shares, respectively, were granted under such programs.

Through acquisitions, the Company assumed obligations to issue shares of M&T common stock related to deferred directors' compensation plans. Shares of common stock issuable under such plans were 1,979 and 2,306 at December 31, 2023 and 2022, respectively. The obligation to issue shares is included in “common stock issuable” in the Consolidated Balance Sheet.

Premises and Equipment - Summary of Premises and Equipment (Detail) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Property, Plant and Equipment [Line Items]
Land	$ 148	$ 149
Buildings	685	654
Leasehold improvements	413	387
Furniture and equipment	1,097	1,004
Premises and equipment, gross	2,343	2,194
Less: accumulated depreciation and amortization	1,220	1,156
Right-of-use assets - operating leases	$ 616	$ 616
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]	Premises and equipment, net	Premises and equipment, net
Premises and equipment, net	$ 1,739	$ 1,654

Investment Securities - Additional Information (Detail)	12 Months Ended
Investment Securities - Additional Information (Detail)	Dec. 31, 2023 USD ($) Security Investment	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Summary of Investment Holdings [Line Items]
Gross realized gains(loss) on sale of investment securities	$ 0	$ 0	$ 0
Number of debt securities with aggregate gross unrealized losses \| Security	4,022
Unrealized losses on individual debt securities	$ (1,300,000,000)
Cost method investment securities	859,000,000
Investment securities pledged to secure debt carrying value	8,200,000,000	7,900,000,000
Carrying value of investment securities pledged related to repurchase transactions	393,000,000	567,000,000
Available-for-Sale Securities [Member]
Summary of Investment Holdings [Line Items]
Allowance for credit losses	$ 0	$ 0
Government Issued or Guaranteed [Member]
Summary of Investment Holdings [Line Items]
Number of investment securities that exceeded ten percent of shareholders' equity \| Investment	0

Loans and Leases - Summary of Current, Past Due and Nonaccrual Loans (Detail) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	$ 132,122	$ 129,492
30-89 Days Past Due	1,724	1,779
Accruing Loans Past Due 90 Days or More	339	491
Nonaccrual	2,166	2,439
Loans and leases, net of unearned discount	134,068	131,564
Current [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	129,839	126,855
Commercial and Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
30-89 Days Past Due	238	498
Accruing Loans Past Due 90 Days or More	11	76
Nonaccrual	670	504
Loans and leases, net of unearned discount	57,010	51,920
Commercial and Industrial [Member] \| Current [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	56,091	50,842
Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
30-89 Days Past Due	311	261
Accruing Loans Past Due 90 Days or More	25	65
Nonaccrual	869	1,240
Loans and leases, net of unearned discount	25,277	26,679
Commercial [Member] \| Current [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	24,072	25,113
Residential Builder and Developer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
30-89 Days Past Due	5	9
Nonaccrual	3	1
Loans and leases, net of unearned discount	1,073	1,315
Residential Builder and Developer [Member] \| Current [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	1,065	1,305
Other Commercial Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
30-89 Days Past Due	159	240
Accruing Loans Past Due 90 Days or More	1
Nonaccrual	171	125
Loans and leases, net of unearned discount	6,653	7,302
Other Commercial Construction [Member] \| Current [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	6,322	6,937
Residential [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
30-89 Days Past Due	763	596
Accruing Loans Past Due 90 Days or More	295	345
Nonaccrual	215	272
Loans and leases, net of unearned discount	22,353	22,705
Residential [Member] \| Current [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	21,080	21,492
Residential Limited Documentation [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
30-89 Days Past Due	31	22
Nonaccrual	55	78
Loans and leases, net of unearned discount	911	1,051
Residential Limited Documentation [Member] \| Current [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	825	951
Home Equity Lines and Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
30-89 Days Past Due	40	31
Nonaccrual	81	85
Loans and leases, net of unearned discount	4,649	5,007
Home Equity Lines and Loans [Member] \| Current [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	4,528	4,891
Recreational Finance [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	9,935
30-89 Days Past Due	87	55
Nonaccrual	36	45
Loans and leases, net of unearned discount	10,058	9,074
Recreational Finance [Member] \| Current [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	9,935	8,974
Automobile [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
30-89 Days Past Due	60	44
Nonaccrual	14	40
Loans and leases, net of unearned discount	3,992	4,477
Automobile [Member] \| Current [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	3,918	4,393
Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	2,003
30-89 Days Past Due	30	23
Accruing Loans Past Due 90 Days or More	7	5
Nonaccrual	52	49
Loans and leases, net of unearned discount	2,092	2,034
Other [Member] \| Current [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	$ 2,003	$ 1,957

Segment Information - Additional Information (Detail) - ReportableSegment	3 Months Ended	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2023
Segment Reporting [Abstract]
Number of reportable segments	3	3

Allowance for credit losses (Tables)

12 Months Ended

Dec. 31, 2023

Receivables [Abstract]

Changes in Allowance for Credit Losses

Changes in the allowance for credit losses for the years ended December 31, 2023, 2022 and 2021 were as follows:


	Commercial			Real Estate
(Dollars in millions)	and industrial			Commercial			Residential			Consumer			Total
2023
Beginning balance	$	568		$	611		$	115		$	631		$	1,925
Provision for credit losses		132			394			4			115			645
Net charge-offs:
Charge-offs		(132	)		(253	)		(10	)		(175	)		(570	)
Recoveries		52			12			7			58			129
Net charge-offs		(80	)		(241	)		(3	)		(117	)		(441	)
Ending balance	$	620		$	764		$	116		$	629		$	2,129

2022
Beginning balance	$	335		$	506		$	72		$	556		$	1,469
Allowance on acquired PCD loans		48			49			2			—			99
Provision for credit losses (a)		244			93			43			137			517
Net charge-offs:
Charge-offs (b)		(119	)		(60	)		(12	)		(112	)		(303	)
Recoveries		60			23			10			50			143
Net charge-offs		(59	)		(37	)		(2	)		(62	)		(160	)
Ending balance	$	568		$	611		$	115		$	631		$	1,925

2021
Beginning balance	$	469		$	607		$	104		$	556		$	1,736
Provision for credit losses		(58	)		(25	)		(30	)		38			(75	)
Net charge-offs:
Charge-offs		(124	)		(100	)		(11	)		(103	)		(338	)
Recoveries		48			24			9			65			146
Net charge-offs		(76	)		(76	)		(2	)		(38	)		(192	)
Ending balance	$	335		$	506		$	72		$	556		$	1,469

________________________________________________

(a)

Includes $242 million related to non-PCD acquired loans recorded on April 1, 2022.

(b)

For the year ended December 31, 2022, net charge-offs do not reflect $33 million of charge-offs related to PCD loans acquired on April 1, 2022.

Loan and Leases Considered Nonaccrual and Interest Income Recognized on Loans


	Amortized Cost with Allowance		Amortized Cost without Allowance		Total		Amortized Cost			Interest Income Recognized
(Dollars in millions)	December 31, 2023							January 1, 2023		Year Ended December 31, 2023
Commercial and industrial	$	397	$	273	$	670		$	504	$	22
Real estate:
Commercial		288		581		869			1,240		29
Residential builder and developer		3		—		3			1		—
Other commercial construction		71		100		171			125		2
Residential		81		134		215			272		15
Residential — limited documentation		19		36		55			78		2
Consumer:
Home equity lines and loans		42		39		81			85		7
Recreational finance		24		12		36			45		1
Automobile		9		5		14			40		—
Other		52		—		52			49		—
Total	$	986	$	1,180	$	2,166		$	2,439	$	78

(Dollars in millions)	December 31, 2022							January 1, 2022		Year Ended December 31, 2022
Commercial and industrial	$	212	$	292	$	504		$	371	$	26
Real estate:
Commercial		366		874		1,240			919		14
Residential builder and developer		1		—		1			3		2
Other commercial construction		59		66		125			111		4
Residential		147		125		272			356		25
Residential — limited documentation		48		30		78			123		1
Consumer:
Home equity lines and loans		43		42		85			70		4
Recreational finance		37		8		45			28		1
Automobile		35		5		40			34		—
Other		49		—		49			45		—
Total	$	997	$	1,442	$	2,439		$	2,060	$	77

(Dollars in millions)	December 31, 2021							January 1, 2021		Year Ended December 31, 2021
Commercial and industrial	$	153	$	218	$	371		$	433	$	23
Real estate:
Commercial		199		720		919			650		5
Residential builder and developer		1		2		3			1		1
Other commercial construction		30		81		111			114		1
Residential		198		158		356			366		24
Residential — limited documentation		80		43		123			147		—
Consumer:
Home equity lines and loans		32		38		70			79		4
Recreational finance		22		6		28			26		1
Automobile		29		5		34			39		—
Other		45		—		45			38		—
Total	$	789	$	1,271	$	2,060		$	1,893	$	59

Summary of Loan grades applied various classes of Commercial and Industrial Loans and Commercial Real Estate Loans


	Term Loans by Origination Year												Revolving		Revolving Loans Converted to Term
(Dollars in millions)	2023		2022		2021		2020		2019		Prior		Loans		Loans		Total
Commercial and industrial:
Loan grades:
Pass	$	8,689	$	8,087	$	4,800	$	2,248	$	2,169	$	4,843	$	22,345	$	70	$	53,251
Criticized accrual		292		279		277		142		127		481		1,460		31		3,089
Criticized nonaccrual		29		68		56		75		36		150		243		13		670
Total commercial and industrial	$	9,010	$	8,434	$	5,133	$	2,465	$	2,332	$	5,474	$	24,048	$	114	$	57,010
Gross charge-offs year ended December 31, 2023	$	10	$	45	$	18	$	13	$	10	$	19	$	17	$	—	$	132
Real estate:
Commercial:
Loan grades:
Pass	$	2,048	$	1,742	$	1,367	$	2,011	$	3,059	$	8,491	$	440	$	—	$	19,158
Criticized accrual		227		891		465		456		966		2,238		7		—		5,250
Criticized nonaccrual		—		46		3		113		93		611		3		—		869
Total commercial real estate	$	2,275	$	2,679	$	1,835	$	2,580	$	4,118	$	11,340	$	450	$	—	$	25,277
Gross charge-offs year ended December 31, 2023	$	—	$	—	$	—	$	—	$	112	$	129	$	—	$	—	$	241
Residential builder and developer:
Loan grades:
Pass	$	530	$	252	$	41	$	6	$	2	$	12	$	116	$	—	$	959
Criticized accrual		1		18		30		—		59		—		3		—		111
Criticized nonaccrual		—		—		3		—		—		—		—		—		3
Total residential builder and developer	$	531	$	270	$	74	$	6	$	61	$	12	$	119	$	—	$	1,073
Gross charge-offs year ended December 31, 2023	$	—	$	—	$	—	$	—	$	—	$	—	$	2	$	—	$	2
Other commercial construction:
Loan grades:
Pass	$	813	$	1,366	$	651	$	373	$	646	$	187	$	30	$	—	$	4,066
Criticized accrual		53		391		390		691		565		326		—		—		2,416
Criticized nonaccrual		—		14		10		46		50		49		2		—		171
Total other commercial construction	$	866	$	1,771	$	1,051	$	1,110	$	1,261	$	562	$	32	$	—	$	6,653
Gross charge-offs year ended December 31, 2023	$	—	$	—	$	—	$	—	$	3	$	7	$	—	$	—	$	10


	Term Loans by Origination Year												Revolving		Revolving Loans Converted to Term
(Dollars in millions)	2022		2021		2020		2019		2018		Prior		Loans		Loans		Total
Commercial and industrial:
Loan grades:
Pass	$	10,217	$	6,582	$	3,110	$	2,989	$	1,752	$	4,615	$	19,794	$	41	$	49,100
Criticized accrual		259		237		234		170		98		527		774		17		2,316
Criticized nonaccrual		21		55		67		51		55		147		101		7		504
Total commercial and industrial	$	10,497	$	6,874	$	3,411	$	3,210	$	1,905	$	5,289	$	20,669	$	65	$	51,920

Real estate:
Commercial:
Loan grades:
Pass	$	2,493	$	1,752	$	2,303	$	3,365	$	2,359	$	8,262	$	521	$	—	$	21,055
Criticized accrual		314		449		424		635		910		1,610		42		—		4,384
Criticized nonaccrual		9		19		155		282		151		601		23		—		1,240
Total commercial real estate	$	2,816	$	2,220	$	2,882	$	4,282	$	3,420	$	10,473	$	586	$	—	$	26,679

Residential builder and developer:
Loan grades:
Pass	$	682	$	230	$	11	$	22	$	13	$	10	$	150	$	—	$	1,118
Criticized accrual		3		28		10		109		15		—		31		—		196
Criticized nonaccrual		—		1		—		—		—		—		—		—		1
Total residential builder and developer	$	685	$	259	$	21	$	131	$	28	$	10	$	181	$	—	$	1,315

Other commercial construction:
Loan grades:
Pass	$	1,033	$	1,080	$	1,226	$	1,186	$	367	$	296	$	16	$	—	$	5,204
Criticized accrual		38		145		321		1,025		299		145		—		—		1,973
Criticized nonaccrual		—		10		44		36		11		22		2		—		125
Total other commercial construction	$	1,071	$	1,235	$	1,591	$	2,247	$	677	$	463	$	18	$	—	$	7,302

Summary of loans in Accrual and Nonaccrual Status

A summary of loans in accrual and nonaccrual status at December 31, 2023 for the various classes of the Company’s residential real estate loans and consumer loans by origination year is as follows:


	Term Loans by Origination Year												Revolving		Revolving Loans Converted to Term
(Dollars in millions)	2023		2022		2021		2020		2019		Prior		Loans		Loans		Total
Residential:
Current	$	1,726	$	4,709	$	3,732	$	2,543	$	1,215	$	7,060	$	95	$	—	$	21,080
30-89 days past due		18		120		88		52		28		457		—		—		763
Accruing loans past due 90 days or more		1		30		28		17		14		205		—		—		295
Nonaccrual		1		17		10		3		4		179		1		—		215
Total residential	$	1,746	$	4,876	$	3,858	$	2,615	$	1,261	$	7,901	$	96	$	—	$	22,353
Gross charge-offs year ended December 31, 2023	$	—	$	—	$	1	$	—	$	3	$	4	$	—	$	—	$	8
Residential - limited documentation:
Current	$	—	$	—	$	—	$	—	$	—	$	825	$	—	$	—	$	825
30-89 days past due		—		—		—		—		—		31		—		—		31
Accruing loans past due 90 days or more		—		—		—		—		—		—		—		—		—
Nonaccrual		—		—		—		—		—		55		—		—		55
Total residential - limited documentation	$	—	$	—	$	—	$	—	$	—	$	911	$	—	$	—	$	911
Gross charge-offs year ended December 31, 2023	$	—	$	—	$	—	$	—	$	—	$	2	$	—	$	—	$	2
Consumer:
Home equity lines and loans:
Current	$	—	$	—	$	2	$	2	$	13	$	98	$	3,022	$	1,391	$	4,528
30-89 days past due		—		—		—		—		—		3		—		37		40
Accruing loans past due 90 days or more		—		—		—		—		—		—		—		—		—
Nonaccrual		—		—		—		—		—		5		3		73		81
Total home equity lines and loans	$	—	$	—	$	2	$	2	$	13	$	106	$	3,025	$	1,501	$	4,649
Gross charge-offs year ended December 31, 2023	$	—	$	—	$	—	$	—	$	—	$	—	$	1	$	5	$	6
Recreational finance:
Current	$	2,653	$	2,338	$	1,857	$	1,286	$	781	$	1,020	$	—	$	—	$	9,935
30-89 days past due		11		16		19		14		11		16		—		—		87
Accruing loans past due 90 days or more		—		—		—		—		—		—		—		—		—
Nonaccrual		3		5		8		6		5		9		—		—		36
Total recreational finance	$	2,667	$	2,359	$	1,884	$	1,306	$	797	$	1,045	$	—	$	—	$	10,058
Gross charge-offs year ended December 31, 2023	$	4	$	13	$	14	$	12	$	9	$	16	$	—	$	—	$	68
Automobile:
Current	$	1,063	$	1,096	$	1,047	$	427	$	198	$	87	$	—	$	—	$	3,918
30-89 days past due		8		15		17		9		6		5		—		—		60
Accruing loans past due 90 days or more		—		—		—		—		—		—		—		—		—
Nonaccrual		2		3		3		2		2		2		—		—		14
Total automobile	$	1,073	$	1,114	$	1,067	$	438	$	206	$	94	$	—	$	—	$	3,992
Gross charge-offs year ended December 31, 2023	$	2	$	6	$	7	$	3	$	2	$	3	$	—	$	—	$	23
Other:
Current	$	250	$	176	$	118	$	33	$	13	$	18	$	1,392	$	3	$	2,003
30-89 days past due		3		3		2		—		—		1		20		1		30
Accruing loans past due 90 days or more		—		—		—		—		—		—		7		—		7
Nonaccrual		2		1		1		—		—		—		48		—		52
Total other	$	255	$	180	$	121	$	33	$	13	$	19	$	1,467	$	4	$	2,092
Gross charge-offs year ended December 31, 2023	$	18	$	17	$	7	$	3	$	3	$	10	$	20	$	—	$	78

Total loans and leases at December 31, 2023	$	18,423	$	21,683	$	15,025	$	10,555	$	10,062	$	27,464	$	29,237	$	1,619	$	134,068
Total gross charge-offs for the year ended December 31, 2023	$	34	$	81	$	47	$	31	$	142	$	190	$	40	$	5	$	570

A summary of loans in accrual and nonaccrual status at December 31, 2022 for the various classes of the Company’s residential real estate loans and consumer loans by origination year follows.


	Term Loans by Origination Year												Revolving		Revolving Loans Converted to Term
(Dollars in millions)	2022		2021		2020		2019		2018		Prior		Loans		Loans		Total
Residential:
Current	$	5,071	$	4,002	$	2,717	$	1,393	$	754	$	7,524	$	31	$	—	$	21,492
30-89 days past due		60		51		40		22		23		399		1		—		596
Accruing loans past due 90 days or more		12		40		20		14		14		245		—		—		345
Nonaccrual		6		11		3		10		5		231		6		—		272
Total residential	$	5,149	$	4,104	$	2,780	$	1,439	$	796	$	8,399	$	38	$	—	$	22,705

Residential - limited documentation:
Current	$	—	$	—	$	—	$	—	$	—	$	951	$	—	$	—	$	951
30-89 days past due		—		—		—		—		—		22		—		—		22
Accruing loans past due 90 days or more		—		—		—		—		—		—		—		—		—
Nonaccrual		—		—		—		—		—		78		—		—		78
Total residential - limited documentation	$	—	$	—	$	—	$	—	$	—	$	1,051	$	—	$	—	$	1,051

Consumer:
Home equity lines and loans:
Current	$	1	$	2	$	2	$	15	$	23	$	97	$	3,264	$	1,487	$	4,891
30-89 days past due		—		—		—		—		1		2		—		28		31
Accruing loans past due 90 days or more		—		—		—		—		—		—		—		—		—
Nonaccrual		—		—		—		1		—		6		3		75		85
Total home equity lines and loans	$	1	$	2	$	2	$	16	$	24	$	105	$	3,267	$	1,590	$	5,007

Recreational finance:
Current	$	2,842	$	2,281	$	1,588	$	964	$	487	$	812	$	—	$	—	$	8,974
30-89 days past due		9		10		12		8		5		11		—		—		55
Accruing loans past due 90 days or more		—		—		—		—		—		—		—		—		—
Nonaccrual		3		7		9		8		6		12		—		—		45
Total recreational finance	$	2,854	$	2,298	$	1,609	$	980	$	498	$	835	$	—	$	—	$	9,074

Automobile:
Current	$	1,491	$	1,558	$	703	$	379	$	167	$	95	$	—	$	—	$	4,393
30-89 days past due		7		13		7		7		6		4		—		—		44
Accruing loans past due 90 days or more		—		—		—		—		—		—		—		—		—
Nonaccrual		2		11		7		8		6		6		—		—		40
Total automobile	$	1,500	$	1,582	$	717	$	394	$	179	$	105	$	—	$	—	$	4,477

Other:
Current	$	274	$	173	$	58	$	39	$	8	$	23	$	1,374	$	8	$	1,957
30-89 days past due		4		1		—		—		—		1		16		1		23
Accruing loans past due 90 days or more		—		—		—		—		—		—		5		—		5
Nonaccrual		3		1		—		—		—		—		45		—		49
Total other	$	281	$	175	$	58	$	39	$	8	$	24	$	1,440	$	9	$	2,034

Total loans and leases at December 31, 2022	$	24,854	$	18,749	$	13,071	$	12,738	$	7,535	$	26,754	$	26,199	$	1,664	$	131,564

Insider Trading Arrangements	12 Months Ended
Insider Trading Arrangements	Dec. 31, 2023
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

Derivative Financial Instruments - Information about Fair Values of Derivative Instruments in Consolidated Balance Sheet (Detail) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value	$ 324	$ 435
Liability Derivatives, Fair Value	943	1,355
Derivatives Not Designated and Qualifying as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value	256	380
Liability Derivatives, Fair Value	898	1,300
Fair Value Hedges [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value	18	4
Liability Derivatives, Fair Value	10	9
Fair Value Hedges [Member] \| Derivatives Not Designated and Qualifying as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value	50	51
Liability Derivatives, Fair Value	35	46
Interest Rate Swap Agreements [Member] \| Fair Value Hedges [Member] \| Derivatives Designated and Qualifying as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value	12	1
Liability Derivatives, Fair Value	2	9
Commitments to Sell Real Estate Loans [Member] \| Fair Value Hedges [Member] \| Derivatives Designated and Qualifying as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value	6	3
Liability Derivatives, Fair Value	8
Commitments to Sell Real Estate Loans [Member] \| Fair Value Hedges [Member] \| Derivatives Not Designated and Qualifying as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value	35	51
Liability Derivatives, Fair Value	3
Commitments to Originate Real Estate Loans for Sale [Member] \| Fair Value Hedges [Member] \| Derivatives Not Designated and Qualifying as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value	15
Liability Derivatives, Fair Value	32	46
Interest Rate Contracts [Member] \| Fair Value Hedges [Member] \| Derivatives Not Designated and Qualifying as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value	237	356
Liability Derivatives, Fair Value	879	1,278
Foreign Exchange and Other Option and Futures Contracts [Member] \| Fair Value Hedges [Member] \| Derivatives Not Designated and Qualifying as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value	19	24
Liability Derivatives, Fair Value	$ 19	$ 22

Parent Company Financial Statements - Condensed Statement of Cash Flows (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Cash flows from operating activities
Net Income (Loss)	$ 2,741	$ 1,992	$ 1,859
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for deferred income taxes	(97)	(30)	87
Net cash provided by operating activities	3,905	4,574	2,715
Cash flows from investing activities
Other, net	(440)	(620)	(511)
Cash flows from financing activities
Proceeds from long-term borrowings	5,035	999	10
Payments on long-term borrowings	(824)	(907)	(853)
Purchases of treasury stock	(594)	(1,800)
Dividends paid — common	(868)	(784)	(580)
Dividends paid — preferred	(100)	(97)	(68)
Proceeds from issuance of Series I preferred stock			495
Other, net	18	(14)	(28)
Net increase (decrease) in cash, cash equivalents and restricted cash	211	182	(215)
Supplemental disclosure of cash flow information
Interest received during the year	10,092	6,135	3,977
Income taxes received during the year	452	488	314
Parent Company [Member]
Cash flows from operating activities
Net Income (Loss)	2,741	1,992	1,859
Adjustments to reconcile net income to net cash provided by operating activities:
Equity in undistributed income of subsidiaries	(847)	448	(855)
Provision for deferred income taxes	(5)	7	10
Net change in accrued income and expense	32	8	(23)
Net cash provided by operating activities	1,921	2,455	991
Cash flows from investing activities
Net investment in consolidated subsidiaries	(1)	54	(199)
Acquisition, net of cash consideration		538
Other, net	(41)	24	(3)
Net cash provided (used) by investing activities	(42)	616	(202)
Cash flows from financing activities
Repayment of short-term borrowings assumed in acquisition		(500)
Proceeds from long-term borrowings	1,998	499
Payments on long-term borrowings	(750)
Purchases of treasury stock	(594)	(1,800)
Dividends paid — common	(868)	(784)	(580)
Dividends paid — preferred	(100)	(97)	(68)
Other, net	14	2	(7)
Net cash used by financing activities	(300)	(2,680)	(160)
Net increase (decrease) in cash, cash equivalents and restricted cash	1,579	391	629
Cash and cash equivalents at beginning of year	1,820	1,429	800
Cash and cash equivalents at end of year	3,399	1,820	1,429
Supplemental disclosure of cash flow information
Interest received during the year	6	1	1
Interest paid during the year	135	49	20
Income taxes received during the year	$ 43	$ 28	53
Parent Company [Member] \| Series I Preferred Stock [Member]
Cash flows from financing activities
Proceeds from issuance of Series I preferred stock			$ 495

Income taxes (Tables)

12 Months Ended

Dec. 31, 2023

Income Tax Disclosure [Abstract]

Components of Income Tax Expense

The components of income tax expense were as follows:


	Year Ended December 31,
(Dollars in millions)	2023			2022			2021
Current:
Federal	$	580		$	367		$	332
State and local		228			143			85
Total current		808			510			417
Deferred:
Federal		(64	)		(18	)		72
State and local		(33	)		(12	)		15
Total deferred		(97	)		(30	)		87
Amortization of investments in qualified affordable housing projects		167			140			92
Total income taxes applicable to pre-tax income	$	878		$	620		$	596

Schedule of Income Tax Expense Benefit Reconciliation

Total income taxes differed from the amount computed by applying the statutory federal income tax rate to pre-tax income as follows:


	Year Ended December 31,
(Dollars in millions)	2023			2022			2021
Income taxes at statutory federal income tax rate	$	760		$	548		$	516
Increase (decrease) in taxes:
Tax-exempt income		(51	)		(37	)		(21	)
State and local income taxes, net of federal income tax effect		161			110			101
Qualified affordable housing project tax benefits, net		(26	)		(22	)		(15	)
Other		34			21			15
	$	878		$	620		$	596

Deferred Tax Assets (Liabilities)

Deferred tax assets (liabilities) were comprised of the following at December 31:


(Dollars in millions)	2023			2022			2021
Losses on loans and other assets	$	686		$	641		$	396
Operating lease liabilities		182			183			110
Postretirement and other employee benefits		47			—			32
Incentive and other compensation plans		30			34			25
Unrealized losses		64			115			—
Interest on loans		42			54			—
Losses on cash flow hedges		52			87			—
Stock-based compensation		54			51			33
Other		153			81			52
Gross deferred tax assets		1,310			1,246			648
Right-of-use assets and other leasing transactions		(336	)		(367	)		(249	)
Unrealized gains		—			—			(27	)
Retirement benefits		(198	)		(88	)		(46	)
Capitalized servicing rights		(38	)		(51	)		(53	)
Postretirement and other employee benefits		—			(29	)		—
Depreciation and amortization		(157	)		(155	)		(93	)
Interest on loans		—			—			(7	)
Gains on cash flow hedges		—			—			(23	)
Other		(59	)		(69	)		(88	)
Gross deferred tax liabilities		(788	)		(759	)		(586	)
Net deferred tax asset	$	522		$	487		$	62

Reconciliation of Beginning and Ending Amount of Unrecognized Tax Benefits

A reconciliation of the beginning and ending amount of unrecognized tax benefits follows:


(Dollars in millions)	Federal, State and Local Tax			Accrued Interest			Unrecognized Income Tax Benefits
Gross unrecognized tax benefits at January 1, 2021	$	49		$	8		$	56
Increases as a result of tax positions taken in prior years		—			3			3
Decreases as a result of tax positions taken in prior years		(11	)		(3	)		(14	)
Gross unrecognized tax benefits at December 31, 2021		38			8			45
Increases as a result of tax positions taken in prior years		—			3			3
Unrecognized tax benefits assumed in a business combination		3			1			5
Decreases as a result of tax positions taken in prior years		(11	)		(4	)		(15	)
Gross unrecognized tax benefits at December 31, 2022		30			8			38
Increases as a result of tax positions taken in prior years		5			1			6
Decreases as a result of tax positions taken in prior years		(13	)		(3	)		(16	)
Gross unrecognized tax benefits at December 31, 2023	$	22		$	6		$	28
Less: Federal, state and local income tax benefits								(6	)
Net unrecognized tax benefits at December 31, 2023 that, if recognized, would impact the effective income tax rate							$	22

Segment information

12 Months Ended

Dec. 31, 2023

Segment Reporting [Abstract]

Segment information

23. Segment information

Reportable segments have been determined based upon the Company’s organizational structure and its internal profitability reporting system. In the fourth quarter of 2023 the Company completed modifications to its internal profitability reporting system to conform its internal management reporting with certain organizational changes that resulted in the realignment of its business operations into three reportable segments: Commercial Bank, Retail Bank and Institutional Services and Wealth Management. All other business activities that are not included in the three reportable segments results have been included in the "All Other" category. The reportable segments have been determined consistent with the Company's customer types and the manner of delivery of its products and services and is reflective of the financial information reviewed by the Company's Chief Executive Officer in evaluating operating decisions and business performance. Beginning in the fourth quarter of 2023, the realigned reportable segments reflect: (1) combining the previously reported Commercial Banking and Commercial Real Estate segments and certain other related activities previously reported in the "All Other" category into one business segment called Commercial Bank; (2) combining the previously reported Retail Banking, Business Banking and Residential Mortgage Banking segments into one business segment called Retail Bank; (3) combining the Institutional Client Services, Wealth Advisory Services and certain other trust-related activities, each previously reported within the "All Other" category, into one new business segment called Institutional Services and Wealth Management; and (4) allocating residential real estate loans previously reported within the Discretionary Portfolio segment into the business segments of Retail Bank and Institutional Services and Wealth Management, with the remainder of such activities being included in the "All Other" category. Certain changes to allocation methodologies for internal transfers for funding charges and credits associated with earning assets and interest-bearing liabilities and other revenues and expenses were also made in conjunction with these reportable segment revisions. Prior period reportable segment results disclosed herein have been presented in conformity with the new segment reporting structure.

The financial information of the Company’s segments was compiled utilizing the accounting policies described in note 1 with certain exceptions. The more significant of these exceptions are described herein. The Company allocates interest income or interest expense using a methodology that

charges users of funds (assets) interest expense and credits providers of funds (liabilities) with income based on the maturity, prepayment and/or repricing characteristics of the assets and liabilities. A provision for credit losses is allocated to segments in an amount based largely on actual net charge-offs incurred by the segment during the period plus or minus an amount necessary to adjust the segment’s allowance for credit losses due to changes in loan balances. In contrast, the level of the consolidated provision for credit losses is determined using the methodologies described in notes 1 and 5. The net effects of these allocations are recorded in the “All Other” category. Indirect fixed and variable expenses incurred by certain centralized support areas are allocated to segments based on actual usage (for example, volume measurements) and other criteria. Certain types of administrative expenses and bankwide expense accruals (including amortization of core deposit and other intangible assets associated with acquisitions of financial institutions) are generally not allocated to segments. Income taxes are allocated to segments based on the Company’s marginal statutory tax rate adjusted for any tax-exempt income or non-deductible expenses. Equity is allocated to the segments based on regulatory capital requirements and in proportion to an assessment of the inherent risks associated with the business of the segment (including interest, credit and operating risk). The management accounting policies and processes utilized in compiling segment financial information are highly subjective and, unlike financial accounting, are not based on authoritative guidance similar to GAAP. As a result, reported segment results are not necessarily comparable with similar information reported by other financial institutions. Furthermore, changes in management structure or allocation methodologies and procedures may result in changes in reported segment financial data.

Information about the Company’s segments is presented in the accompanying table.


	For the Years Ended December 31,
	Commercial Bank									Retail Bank							Institutional Services and Wealth Management
(Dollars in millions)	2023			2022			2021			2023		2022		2021			2023		2022			2021
Net interest income (a)	$	2,409		$	2,302		$	1,558		$	4,352	$	3,008	$	1,929		$	700	$	403		$	156
Noninterest income		658			588			509			762		703		831			1,005		1,007			766
		3,067			2,890			2,067			5,114		3,711		2,760			1,705		1,410			922
Provision for credit losses		297			66			169			173		101		69			—		(1	)		—
Amortization of core deposit and other intangible assets		—			—			1			—		—		—			—		—			—
Depreciation and other amortization		39			39			39			249		198		152			8		8			9
Other noninterest expense		1,307			1,085			748			2,208		2,009		1,508			859		859			768
Income (loss) before taxes		1,424			1,700			1,110			2,484		1,403		1,031			838		544			145
Income tax expense (benefit)		385			458			297			646		364		266			218		142			38
Net income (loss)	$	1,039		$	1,242		$	813		$	1,838	$	1,039	$	765		$	620	$	402		$	107
Average total assets	$	80,243		$	69,960		$	53,578		$	51,213	$	49,059	$	43,736		$	3,675	$	3,598		$	3,260
Capital expenditures	$	2		$	2		$	3		$	104	$	122	$	55		$	6	$	2		$	12

	All Other									Total
(Dollars in millions)	2023			2022			2021			2023		2022		2021
Net interest income (a)	$	(346	)	$	109		$	182		$	7,115	$	5,822	$	3,825
Noninterest income		103			59			61			2,528		2,357		2,167
		(243	)		168			243			9,643		8,179		5,992
Provision for credit losses		175			351			(313	)		645		517		(75	)
Amortization of core deposit and other intangible assets		62			56			9			62		56		10
Depreciation and other amortization		139			134			114			435		379		314
Other noninterest expense		508			662			264			4,882		4,615		3,288
Income (loss) before taxes		(1,127	)		(1,035	)		169			3,619		2,612		2,455
Income tax expense (benefit)		(371	)		(344	)		(5	)		878		620		596
Net income (loss)	$	(756	)	$	(691	)	$	174		$	2,741	$	1,992	$	1,859
Average total assets	$	70,266		$	67,635		$	52,095		$	205,397	$	190,252	$	152,669
Capital expenditures	$	144		$	88		$	79		$	256	$	214	$	149

(a)

The Commercial Bank segment provides a wide range of credit products and banking services to middle-market and large commercial customers, mainly within the markets served by the Company. Services provided by this segment include commercial lending and leasing, credit facilities which are secured by various types of commercial real estate, letters of credit, deposit products and cash management services. Commercial real estate loans may be secured by multifamily residential buildings, hotels, office, retail and industrial space or other types of collateral. Activities of this segment include the origination, sales and servicing of commercial real estate loans through the Fannie Mae DUS program and other programs. Commercial real estate loans held for sale are included in this segment.

The Retail Bank segment provides a wide range of services to consumers and small businesses through the Company’s branch network and several other delivery channels such as telephone banking, internet banking and automated teller machines. The Company has branch offices in New York State, Maryland, New Jersey, Pennsylvania, Delaware, Connecticut, Massachusetts, Maine, Vermont, New Hampshire, Virginia, West Virginia and the District of Columbia. The segment offers to its customers deposit products, including demand, savings and time accounts, and other services. Credit services offered by this segment include automobile and recreational finance loans (originated both directly and indirectly through dealers), home equity loans and lines of credit, credit cards and other loan products. This segment also originates and services residential mortgage loans and either sells those loans in the secondary market to investors or retains them for investment purposes. Residential mortgage loans are also originated and serviced on behalf of the Institutional Services and Wealth Management segment. The Company periodically purchases the rights to service residential real estate loans that have been originated by other entities and also sub-services residential real estate loans for others. Residential

real estate loans held for sale are included in this segment. This segment also provides various business loans, including loans guaranteed by the SBA, business credit cards, deposit products and services such as cash management, payroll and direct deposit, merchant credit card and letters of credits to small businesses and professionals through the Company's branch network and other delivery channels.

The Institutional Services and Wealth Management segment provides a variety of trustee, agency, investment management and administrative services for corporations and institutions, investment bankers, corporate tax, finance and legal executives, and other institutional clients, as well as personal trust, planning, fiduciary, asset management, family office and other services designed to help high net worth individuals and families grow, preserve and transfer wealth. This segment also provides investment products, including mutual funds and annuities and other services to customers.

The “All Other” category reflects other activities of the Company that are not directly attributable to the reported segments. Reflected in this category are the difference between the provision for credit losses and the calculated provision allocated to the reportable segments; goodwill and core deposit and other intangible assets resulting from the acquisitions of financial institutions; merger-related gains and expenses related to acquisitions; the net impact of the Company’s internal funds transfer pricing methodology; eliminations of transactions between reportable segments; certain non-recurring transactions; and the residual effects of unallocated support systems and general and administrative expenses. The Company’s investment securities portfolio, brokered deposits and short-term and long-term borrowings are generally included in the “All Other” category. In its management of interest rate risk, the Company utilizes interest rate swap agreements to modify the repricing characteristics of certain portfolios of earning assets and interest-bearing liabilities. The results of such activities are captured in the "All Other" category.

The amount of intersegment activity eliminated in arriving at consolidated totals was included in the “All Other” category as follows:


	Year Ended December 31,
(Dollars in millions)	2023			2022			2021
Revenues	$	(17	)	$	(14	)	$	(12	)
Expenses		(3	)		(2	)		(2	)
Income taxes		(4	)		(3	)		(3	)
Net income		(10	)		(9	)		(7	)

There are no transactions with a single customer that in the aggregate result in revenues that exceed ten percent of consolidated total revenues.

- Definition

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 22
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-22

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 15
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-15

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 31
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-31

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 32
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-32

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 42
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-42

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 32
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-32

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 40
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-40

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org//280/tableOfContent

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 26
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-26

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 34
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-34

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
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-Name Accounting Standards Codification
-Section 50
-Paragraph 41
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-41

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 21
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-21

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 21
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-21

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 32
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-32

+ Details

Derivative Financial Instruments - Information about Fair Values of Derivative Instruments in Consolidated Balance Sheet (Parenthetical) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Offsetting [Abstract]
Reduction in estimated fair value of interest rate contracts in asset position	$ 783	$ 1,100
Reduction in estimated fair value of interest rate contracts in liability position	$ 32	$ 29

Regulatory matters (Tables)

12 Months Ended

Dec. 31, 2023

Broker-Dealer, Net Capital Requirement, SEC Regulation [Abstract]

Summary of Required Minimum and Well Capitalized Capital Ratios

Pursuant to the rules in effect as of December 31, 2023, the required minimum and well capitalized capital ratios are as follows:


				Well
	Minimum			Capitalized
M&T (Consolidated)
CET1 to RWA		4.5	%
Tier 1 capital to RWA		6.0			6.0	%
Total capital to RWA		8.0			10.0
Leverage — Tier 1 capital to average total assets, as defined		4.0

				Well
	Minimum			Capitalized
Bank Subsidiaries
CET1 to RWA		4.5	%		6.5	%
Tier 1 capital to RWA		6.0			8.0
Total capital to RWA		8.0			10.0
Leverage — Tier 1 capital to average total assets, as defined		4.0			5.0

Capital Ratios and Amounts of Company and its Banking Subsidiaries

The capital ratios and amounts of the Company and its banking subsidiaries as of December 31, 2023 and 2022 are presented below:


(Dollars in millions)	M&T (Consolidated)			M&T Bank			Wilmington Trust, N.A.
December 31, 2023:
CET1 capital
Amount	$	16,908		$	17,667		$	583
Ratio(a)		10.98	%		11.53	%		263.48	%
Tier 1 capital
Amount	$	18,918		$	17,667		$	583
Ratio(a)		12.29	%		11.53	%		263.48	%
Total capital
Amount	$	21,533		$	19,884		$	584
Ratio(a)		13.99	%		12.97	%		263.85	%
Leverage
Amount	$	18,918		$	17,667		$	583
Ratio(b)		9.43	%		8.83	%		86.00	%
December 31, 2022:
CET1 capital
Amount	$	15,562		$	16,674		$	586
Ratio(a)		10.44	%		11.23	%		254.50	%
Tier 1 capital
Amount	$	17,573		$	16,674		$	586
Ratio(a)		11.79	%		11.23	%		254.50	%
Total capital
Amount	$	20,260		$	18,888		$	587
Ratio(a)		13.60	%		12.72	%		254.90	%
Leverage
Amount	$	17,573		$	16,674		$	586
Ratio(b)		9.23	%		8.77	%		85.73	%

(a)

The ratio of capital to RWA, as defined by regulation.

(b)

The ratio of capital to average assets, as defined by regulation.

Stock-Based Compensation Plans - Summary of Restricted Stock and Restricted Stock Unit Activity (Detail)	12 Months Ended
	Dec. 31, 2023 $ / shares shares
Restricted Stock Units (RSUs) [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Restricted Stock Outstanding, Unvested, Beginning balance \| shares	1,167,582
Restricted Stock Outstanding, Granted \| shares	752,534
Restricted Stock Outstanding, Vested \| shares	(543,987)
Restricted Stock Outstanding, Cancelled \| shares	(45,851)
Restricted Stock Outstanding, Unvested, Ending balance \| shares	1,330,278
Weighted-Average Grant Price, Unvested, Beginning balance \| $ / shares	$ 156.23
Weighted-Average Grant Price, Granted \| $ / shares	153.86
Weighted-Average Grant Price, Vested \| $ / shares	156.97
Weighted-Average Grant Price, Cancelled \| $ / shares	159.73
Weighted-Average Grant Price, Unvested, Ending balance \| $ / shares	$ 154.46
Restricted Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Restricted Stock Outstanding, Unvested, Beginning balance \| shares	75,006
Restricted Stock Outstanding, Vested \| shares	(35,777)
Restricted Stock Outstanding, Cancelled \| shares	(7,514)
Restricted Stock Outstanding, Unvested, Ending balance \| shares	31,715
Weighted-Average Grant Price, Unvested, Beginning balance \| $ / shares	$ 164.65
Weighted-Average Grant Price, Vested \| $ / shares	164.66
Weighted-Average Grant Price, Cancelled \| $ / shares	164.66
Weighted-Average Grant Price, Unvested, Ending balance \| $ / shares	$ 164.63

Allowance for Credit Losses - Changes in Allowance for Credit Losses (Parenthetical) (Detail) - USD ($) $ in Millions		12 Months Ended
	Apr. 01, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Financing Receivable, Allowance for Credit Loss [Line Items]
Provision for credit losses		$ 645	$ 517	$ (75)
Charge-offs		$ (570)	$ (303)	$ (338)
Non PCD Acquired Loans [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Provision for credit losses	$ 242
Charge-offs	(242)
PCD Acquired Loans [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Charge-offs	$ (33)

Fair Value Measurements - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Weighted-average discount rates for fair value estimations	46.00%
Historical recovery rate of collateral values of consumer installment loans	49.00%
Residential Mortgage Loans [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Capitalized servicing rights	$ 456,000,000	$ 194,000,000	$ 241,000,000	$ 231,000,000
Capitalized servicing rights, valuation allowance			(24,000,000)
Weighted-average prepayment speeds	6.93%
Minimum [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Discount rates for fair value estimations	10.00%
Maximum [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Discount rates for fair value estimations	90.00%
Significant Unobservable Inputs (Level 3) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Change in fair value of nonrecurring fair value measured loans for charge-offs and impairment reserves	$ (381,000,000)	(191,000,000)	(53,000,000)
Significant Unobservable Inputs (Level 3) [Member] \| Residential Mortgage Loans [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Capitalized servicing rights, valuation allowance	0	0
Valuation Charge Recognized		24,000,000	6,000,000
Fair Value, Measurements, Nonrecurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Loans measured at fair value on nonrecurring basis	923,000,000	853,000,000	574,000,000
Fair Value, Measurements, Nonrecurring [Member] \| Significant Observable Inputs (Level 2) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Loans measured at fair value on nonrecurring basis	234,000,000	329,000,000	340,000,000
Fair Value, Measurements, Nonrecurring [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Loans measured at fair value on nonrecurring basis	$ 689,000,000	$ 524,000,000	$ 234,000,000

Borrowings

12 Months Ended

Dec. 31, 2023

Debt Disclosure [Abstract]

Borrowings

9. Borrowings

The amounts and interest rates of short-term borrowings were as follows:


(Dollars in millions)	Repurchase Agreements			FHLB Advances			Total
At December 31, 2023
Amount outstanding	$	316		$	5,000		$	5,316
Weighted-average interest rate		3.26	%		5.35	%		5.23	%
At December 31, 2022
Amount outstanding	$	355		$	3,200		$	3,555
Weighted-average interest rate		1.01	%		4.59	%		4.24	%

Short-term borrowings have a stated maturity of one year or less at the date the Company enters into the obligation. All outstanding short-term borrowings at December 31, 2023 are set to mature in the first quarter of 2024.

At December 31, 2023, M&T Bank had borrowing facilities available with the FHLB of New York whereby M&T Bank could borrow up to approximately $16.8 billion. Additionally, M&T Bank had an available line of credit with the FRB of New York totaling approximately $17.1 billion at December 31, 2023. Outstanding borrowings on such facilities totaled $5.0 billion at December 31, 2023. M&T Bank is required to pledge loans and investment securities as collateral for these borrowing facilities.

Long-term borrowings were as follows:


	December 31,
(Dollars in millions)	2023		2022
Senior notes of M&T:
Variable rate due 2023	$	—	$	250
3.55% due 2023		—		494
4.55% fixed/variable due 2028		484		477
7.41% fixed/variable due 2029		1,028		—
5.05% fixed/variable due 2034		970		—
Senior notes of M&T Bank:
2.90% due 2025		750		750
5.40% due 2025		499		499
4.65% due 2026		1,296		—
4.70% due 2028		1,196		—
Subordinated notes of M&T:
5.75% due 2024		76		77
Subordinated notes of M&T Bank:
4.00% due 2024		401		404
3.40% due 2027		472		463
Junior subordinated debentures of M&T associated with preferred capital securities:
Fixed rates:
BSB Capital Trust I — 8.125%, due 2028		16		16
Provident Trust I — 8.29%, due 2028		32		31
Southern Financial Statutory Trust I — 10.60%, due 2030		7		7
Variable rates:
First Maryland Capital I — due 2027		150		150
First Maryland Capital II — due 2027		153		152
Allfirst Asset Trust — due 2029		98		97
BSB Capital Trust III — due 2033		15		15
Provident Statutory Trust III — due 2033		60		59
Southern Financial Capital Trust III — due 2033		9		9
Asset-backed notes		474		—
Other		15		15
	$	8,201	$	3,965

The variable rate senior notes of M&T were repaid in 2023 and paid interest quarterly at a rate that was indexed to the three-month LIBOR. The contractual interest rate was 5.00% at December 31, 2022.

The Junior Subordinated Debentures are held by various trusts and were issued in connection with the issuance by those trusts of Preferred Capital Securities and Common Securities. The proceeds from the issuances of the Preferred Capital Securities and the Common Securities were used by the trusts to purchase the Junior Subordinated Debentures. The Common Securities of each of those trusts are wholly owned by M&T and are the only class of each trust’s securities possessing general voting powers. The Preferred Capital Securities represent preferred undivided interests in the assets of the corresponding trust. Under the Federal Reserve’s risk-based capital guidelines, the Preferred Capital Securities qualify for inclusion in Tier 2 regulatory capital. The variable rate Junior Subordinated Debentures pay interest quarterly at rates that are indexed to the three-month SOFR. Those rates ranged from 6.49% to 9.01% at December 31, 2023 and from 5.08% to 7.69% at December 31, 2022. The weighted-average variable rates payable on those Junior Subordinated Debentures were 7.07% at December 31, 2023 and 5.66% at December 31, 2022.

Holders of the Preferred Capital Securities receive preferential cumulative cash distributions unless M&T exercises its right to extend the payment of interest on the Junior Subordinated Debentures as allowed by the terms of each such debenture, in which case payment of distributions on the respective Preferred Capital Securities will be deferred for comparable periods. During an extended interest period, M&T may not pay dividends or distributions on, or repurchase, redeem or acquire any shares of its capital stock. In general, the agreements governing the Preferred Capital Securities, in the aggregate, provide a full, irrevocable and unconditional guarantee by M&T of the payment of distributions on, the redemption of, and any liquidation distribution with respect to the Preferred Capital Securities. The obligations under such guarantee and the Preferred Capital Securities are subordinate and junior in right of payment to all senior indebtedness of M&T.

The Preferred Capital Securities will remain outstanding until the Junior Subordinated Debentures are repaid at maturity, are redeemed prior to maturity or are distributed in liquidation to the trusts. The Preferred Capital Securities are mandatorily redeemable in whole, but not in part, upon repayment at the stated maturity dates (ranging from 2027 to 2033) of the Junior Subordinated Debentures or the earlier redemption of the Junior Subordinated Debentures in whole upon the occurrence of one or more events set forth in the indentures relating to the Preferred Capital Securities, and in whole or in part at any time after an optional redemption prior to contractual maturity contemporaneously with the optional redemption of the related Junior Subordinated Debentures in whole or in part, subject to possible regulatory approval.

In August 2023, a subsidiary of M&T Bank issued asset-backed notes secured by equipment finance loans and leases. A total of $550 million of such notes, representing the senior-most notes in the securitization, were purchased by third parties. At December 31, 2023, the outstanding asset-backed notes totaled $474 million and had a weighted-average estimated life of approximately two years and a weighted-average interest rate of 5.89%. Further information about this financing transaction is provided in note 20.

Long-term borrowings at December 31, 2023 mature as follows:


(Dollars in millions)
Year ending December 31:
2024	$	527
2025		1,251
2026		1,297
2027		775
2028		1,728
Later years		2,623
	$	8,201

- Definition

The entire disclosure for information about short-term and long-term debt arrangements, which includes amounts of borrowings under each line of credit, note payable, commercial paper issue, bonds indenture, debenture issue, own-share lending arrangements and any other contractual agreement to repay funds, and about the underlying arrangements, rationale for a classification as long-term, including repayment terms, interest rates, collateral provided, restrictions on use of assets and activities, whether or not in compliance with debt covenants, and other matters important to users of the financial statements, such as the effects of refinancing and noncompliance with debt covenants.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Subparagraph (h)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1B

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(c))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480678/235-10-S99-1

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 470
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org//470/tableOfContent

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1B

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Subparagraph (g)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1B

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Subparagraph (i)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1B

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1C
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1C

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1C
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1C

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1C
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1C

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1E
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1E

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1I
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1I

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1I
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1I

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1I
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1I

+ Details

Pension Plans and Other Postretirement Benefits - Assumed Weighted-Average Rates Used to Determine Net Benefit Expense (Detail)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Pension Benefits [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Discount rate	5.00%	2.75%	2.50%
Long-term rate of return on plan assets	6.25%	6.25%	6.25%
Rate of increase in future compensation levels	3.33%	3.35%	3.37%
Other Postretirement Benefits [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Discount rate	5.00%	2.75%	2.50%

Fair Value Measurements - Carrying Amounts and Estimated Fair Value for Financial Instrument Assets (Liabilities) (Detail) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Financial assets:
Interest-bearing deposits at banks	$ 28,069	$ 24,959
Federal funds sold		3
Investment securities	26,897	25,211
Loans and leases, net	131,939	129,639
Financial liabilities:
Noninterest-bearing deposits	(49,294)	(65,502)
Savings and interest-checking deposits	(93,221)	(87,911)
Time deposits	(20,759)	(10,102)
Long-term borrowings	(8,201)	(3,965)
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Financial assets:
Cash and cash equivalents	1,668	1,372
Trading account	101	118
Investment securities	258	145
Significant Observable Inputs (Level 2) [Member]
Financial assets:
Cash and cash equivalents	63	145
Interest-bearing deposits at banks	28,069	24,959
Federal funds sold		3
Trading account	5
Investment securities	25,571	23,860
Loans and leases, net	7,240	7,180
Accrued interest receivable	786	646
Financial liabilities:
Noninterest-bearing deposits	(49,294)	(65,502)
Savings and interest-checking deposits	(93,221)	(87,911)
Time deposits	(20,715)	(10,143)
Short-term borrowings	(5,316)	(3,555)
Long-term borrowings	(8,107)	(3,926)
Accrued interest payable	(482)	(81)
Other financial instruments:
Commitments to sell real estate loans	30	54
Interest rate swap agreements used for interest rate risk management	10	(8)
Interest rate and foreign exchange contracts not designated as hedging instruments	(642)	(920)
Significant Unobservable Inputs (Level 3) [Member]
Financial assets:
Investment securities	46	51
Loans and leases, net	121,898	119,048
Other financial instruments:
Commitments to originate real estate loans for sale	(17)	(46)
Other credit-related commitments	154	(149)
Carrying Amount [Member]
Financial assets:
Cash and cash equivalents	1,731	1,517
Interest-bearing deposits at banks	28,069	24,959
Federal funds sold		3
Trading account	106	118
Investment securities	26,897	25,211
Loans and leases, net	131,939	129,639
Accrued interest receivable	786	646
Financial liabilities:
Noninterest-bearing deposits	(49,294)	(65,502)
Savings and interest-checking deposits	(93,221)	87,911
Time deposits	(20,759)	(10,102)
Short-term borrowings	(5,316)	(3,555)
Long-term borrowings	(8,201)	(3,965)
Accrued interest payable	(482)	(81)
Other financial instruments:
Commitments to originate real estate loans for sale	(17)	(46)
Commitments to sell real estate loans	30	54
Other credit-related commitments	154	149
Interest rate swap agreements used for interest rate risk management	10	(8)
Interest rate and foreign exchange contracts not designated as hedging instruments	(642)	(920)
Cumulative Amount of Fair Value Hedging Adjustment Increasing (Decreasing) the Carrying Amount [Member]
Financial assets:
Cash and cash equivalents	1,731	1,517
Interest-bearing deposits at banks	28,069	24,959
Federal funds sold		3
Trading account	106	118
Investment securities	25,875	24,056
Loans and leases, net	129,138	126,228
Accrued interest receivable	786	646
Financial liabilities:
Noninterest-bearing deposits	(49,294)	(65,502)
Savings and interest-checking deposits	(93,221)	87,911
Time deposits	(20,715)	(10,143)
Short-term borrowings	(5,316)	(3,555)
Long-term borrowings	(8,107)	(3,926)
Accrued interest payable	(482)	(81)
Other financial instruments:
Commitments to originate real estate loans for sale	(17)	(46)
Commitments to sell real estate loans	30	54
Other credit-related commitments	(154)	149
Interest rate swap agreements used for interest rate risk management	10	(8)
Interest rate and foreign exchange contracts not designated as hedging instruments	$ (642)	$ (920)

Revenue from Contracts with Customers - Summary of Sources of Noninterest Income that are Subject to Revenue Recognition Guidance (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Disaggregation Of Revenue [Line Items]
Brokerage services income	$ 102	$ 88	$ 63
Other revenues from operations:
Total other income	2,528	2,357	2,167
Service Charges on Deposit Accounts [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	475	447	402
Trust Income [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	680	741	645
ASU 2014-09 [Member]
Disaggregation Of Revenue [Line Items]
Brokerage services income	102	88	63
Other revenues from operations:
Merchant discount and credit card interchange fees	161	159	131
Other	66	90	83
Total other income	1,484	1,525	1,324
ASU 2014-09 [Member] \| Service Charges on Deposit Accounts [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	475	447	402
ASU 2014-09 [Member] \| Trust Income [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	680	741	645
ASU 2014-09 [Member] \| Commercial Banking [Member] \| Service Charges on Deposit Accounts [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	144	130
ASU 2014-09 [Member] \| Commercial Banking [Member] \| Trust Income [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	2
ASU 2014-09 [Member] \| Commercial Bank [Member]
Disaggregation Of Revenue [Line Items]
Brokerage services income	6	5	2
Other revenues from operations:
Merchant discount and credit card interchange fees	77	73	58
Other	28	24	13
Total other income	257	232	188
ASU 2014-09 [Member] \| Commercial Bank [Member] \| Service Charges on Deposit Accounts [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer			115
ASU 2014-09 [Member] \| Institutional Services and Wealth Management [ Member]
Disaggregation Of Revenue [Line Items]
Brokerage services income	96	83	61
Other revenues from operations:
Other	8	38	40
Total other income	783	862	746
ASU 2014-09 [Member] \| Institutional Services and Wealth Management [ Member] \| Service Charges on Deposit Accounts [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	1
ASU 2014-09 [Member] \| Institutional Services and Wealth Management [ Member] \| Trust Income [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	678	741	645
ASU 2014-09 [Member] \| Retail Bank [Member]
Other revenues from operations:
Merchant discount and credit card interchange fees	84	86	73
Other	30	28	30
Total other income	444	431	390
ASU 2014-09 [Member] \| Retail Bank [Member] \| Service Charges on Deposit Accounts [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	$ 330	$ 317	$ 287

Commitments and contingencies

12 Months Ended

Dec. 31, 2023

Commitments and Contingencies Disclosure [Abstract]

Commitments and contingencies

22. Commitments and contingencies

In the normal course of business, various commitments and contingent liabilities are outstanding. The following table presents the Company’s significant commitments. Certain of these commitments are not included in the Company’s Consolidated Balance Sheet.


	December 31,		December 31,
(Dollars in millions)	2023		2022
Commitments to extend credit:
Commercial and industrial	$	28,566	$	27,471
Commercial real estate loans to be sold		916		349
Other commercial real estate		5,019		5,084
Residential real estate loans to be sold		163		31
Other residential real estate		331		505
Home equity lines of credit		8,109		8,262
Credit cards		5,578		5,465
Other		413		382
Standby letters of credit		2,289		2,377
Commercial letters of credit		62		65
Financial guarantees and indemnification contracts		4,036		4,022
Commitments to sell real estate loans		1,400		533

Commitments to extend credit are agreements to lend to customers, generally having fixed expiration dates or other termination clauses that may require payment of a fee. In addition to the amounts presented in the preceding table, the Company had discretionary funding commitments to commercial customers of $12.3 billion and $11.7 billion at December 31, 2023 and 2022, respectively, that the Company had the unconditional right to cancel prior to funding. Standby and commercial letters of credit are conditional commitments issued to guarantee the performance of a customer to a third party. Standby letters of credit generally are contingent upon the failure of the customer to perform according to the terms of the underlying contract with the third party, whereas commercial letters of credit are issued to facilitate commerce and typically result in the commitment being funded when the underlying transaction is consummated between the customer and a third party. The credit risk associated with commitments to extend credit and standby and commercial letters of credit is essentially the same as that involved with extending loans to customers and is subject to normal credit policies. Collateral may be obtained based on management’s assessment of the customer’s creditworthiness.

Financial guarantees and indemnification contracts are predominantly comprised of recourse obligations associated with sold loans and other guarantees and commitments. Included in financial guarantees and indemnification contracts are loan principal amounts sold with recourse in conjunction with the Company’s involvement in the Fannie Mae DUS program. The Company’s maximum credit risk for recourse associated with loans sold under this program totaled approximately $3.9 billion at each of December 31, 2023 and 2022. At December 31, 2023, the Company estimated that the recourse obligations described above were not material to the Company’s consolidated financial position. There have been no material losses incurred as a result of those credit recourse arrangements.

Since many loan commitments, standby letters of credit, and guarantees and indemnification contracts expire without being funded in whole or in part, the contract amounts are not necessarily indicative of future cash flows.

The Company utilizes commitments to sell real estate loans to hedge exposure to changes in the fair value of real estate loans held for sale. Such commitments are accounted for as derivatives and along with commitments to originate real estate loans to be held for sale are recorded in the Consolidated Balance Sheet at estimated fair market value.

The Company is contractually obligated to repurchase previously sold residential real estate loans that do not ultimately meet investor sale criteria related to underwriting procedures or loan

documentation. When required to do so, the Company may reimburse loan purchasers for losses incurred or may repurchase certain loans. The Company reduces residential mortgage banking revenues by an estimate for losses related to its obligations to loan purchasers. The amount of those charges is based on the volume of loans sold, the level of reimbursement requests received from loan purchasers and estimates of losses that may be associated with previously sold loans. At December 31, 2023, the Company believes that its obligation to loan purchasers was not material to the Company’s consolidated financial position.

M&T and its subsidiaries are subject in the normal course of business to various pending and threatened legal proceedings and other matters in which claims for monetary damages are asserted. On an on-going basis management, after consultation with legal counsel, assesses the Company’s liabilities and contingencies in connection with such proceedings. For those matters where it is probable that the Company will incur losses and the amounts of the losses can be reasonably estimated, the Company records an expense and corresponding liability in its consolidated financial statements. To the extent the pending or threatened litigation could result in exposure in excess of that liability, the amount of such excess is not currently estimable. Although not considered probable, the range of reasonably possible losses for such matters in the aggregate, beyond the existing recorded liability, was between $0 and $25 million at December 31, 2023. Although the Company does not believe that the outcome of pending litigations will be material to the Company’s consolidated financial position, it cannot rule out the possibility that such outcomes will be material to the consolidated results of operations for a particular reporting period in the future.

Allowance for Credit Losses - Summary of loans in Accrual and Nonaccrual Status (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Financing Receivable Recorded Investment [Line Items]
Total loans	$ 132,122	$ 129,492
30-89 Days Past Due	1,724	1,779
Accruing Loans Past Due 90 Days or More	339	491
Nonaccrual	2,166	2,439
Loans and leases, net of unearned discount	134,068	131,564
Gross charge-offs	570
Revolving Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	29,237	26,199
Gross charge-offs	40
Revolving Loans Converted to Term Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	1,619	1,664
Gross charge-offs	5
Residential [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due	763	596
Accruing Loans Past Due 90 Days or More	295	345
Nonaccrual	215	272
Loans and leases, net of unearned discount	22,353	22,705
Gross charge-offs	8
Residential [Member] \| Revolving Loans [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due		1
Nonaccrual	1	6
Loans and leases, net of unearned discount	96	38
Residential Limited Documentation [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due	31	22
Nonaccrual	55	78
Loans and leases, net of unearned discount	911	1,051
Gross charge-offs	2
Home Equity Lines and Loans [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due	40	31
Nonaccrual	81	85
Loans and leases, net of unearned discount	4,649	5,007
Gross charge-offs	6
Home Equity Lines and Loans [Member] \| Revolving Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Nonaccrual	3	3
Loans and leases, net of unearned discount	3,025	3,267
Gross charge-offs	1
Home Equity Lines and Loans [Member] \| Revolving Loans Converted to Term Loans [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due	37	28
Nonaccrual	73	75
Loans and leases, net of unearned discount	1,501	1,590
Gross charge-offs	5
Recreational Finance [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	9,935
30-89 Days Past Due	87	55
Nonaccrual	36	45
Loans and leases, net of unearned discount	10,058	9,074
Gross charge-offs	68
Automobile [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due	60	44
Nonaccrual	14	40
Loans and leases, net of unearned discount	3,992	4,477
Gross charge-offs	23
Other [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	2,003
30-89 Days Past Due	30	23
Accruing Loans Past Due 90 Days or More	7	5
Nonaccrual	52	49
Loans and leases, net of unearned discount	2,092	2,034
Gross charge-offs	78
Other [Member] \| Revolving Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	1,392
30-89 Days Past Due	20	16
Accruing Loans Past Due 90 Days or More	7	5
Nonaccrual	48	45
Loans and leases, net of unearned discount	1,467	1,440
Gross charge-offs	20
Other [Member] \| Revolving Loans Converted to Term Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	3
30-89 Days Past Due	1	1
Nonaccrual
Loans and leases, net of unearned discount	4	9
Current [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	129,839	126,855
Current [Member] \| Residential [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	21,080	21,492
Current [Member] \| Residential [Member] \| Revolving Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	95	31
Current [Member] \| Residential Limited Documentation [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	825	951
Current [Member] \| Home Equity Lines and Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	4,528	4,891
Current [Member] \| Home Equity Lines and Loans [Member] \| Revolving Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	3,022	3,264
Current [Member] \| Home Equity Lines and Loans [Member] \| Revolving Loans Converted to Term Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	1,391	1,487
Current [Member] \| Recreational Finance [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	9,935	8,974
Current [Member] \| Automobile [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	3,918	4,393
Current [Member] \| Other [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	2,003	1,957
Current [Member] \| Other [Member] \| Revolving Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		1,374
Current [Member] \| Other [Member] \| Revolving Loans Converted to Term Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		8
Term Loans 2023 [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	18,423
Gross charge-offs	34
Term Loans 2023 [Member] \| Residential [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due	18
Accruing Loans Past Due 90 Days or More	1
Nonaccrual	1
Loans and leases, net of unearned discount	1,746
Term Loans 2023 [Member] \| Recreational Finance [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	2,653
30-89 Days Past Due	11
Nonaccrual	3
Loans and leases, net of unearned discount	2,667
Gross charge-offs	4
Term Loans 2023 [Member] \| Automobile [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due	8
Nonaccrual	2
Loans and leases, net of unearned discount	1,073
Gross charge-offs	2
Term Loans 2023 [Member] \| Other [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	250
30-89 Days Past Due	3
Nonaccrual	2
Loans and leases, net of unearned discount	255
Gross charge-offs	18
Term Loans 2023 [Member] \| Current [Member] \| Residential [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	1,726
Term Loans 2023 [Member] \| Current [Member] \| Automobile [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	1,063
Term Loans 2022 [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	21,683	24,854
Gross charge-offs	81
Term Loans 2022 [Member] \| Residential [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due	120	60
Accruing Loans Past Due 90 Days or More	30	12
Nonaccrual	17	6
Loans and leases, net of unearned discount	4,876	5,149
Term Loans 2022 [Member] \| Home Equity Lines and Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount		1
Term Loans 2022 [Member] \| Recreational Finance [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	2,338
30-89 Days Past Due	16	9
Nonaccrual	5	3
Loans and leases, net of unearned discount	2,359	2,854
Gross charge-offs	13
Term Loans 2022 [Member] \| Automobile [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due	15	7
Nonaccrual	3	2
Loans and leases, net of unearned discount	1,114	1,500
Gross charge-offs	6
Term Loans 2022 [Member] \| Other [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	176
30-89 Days Past Due	3	4
Nonaccrual	1	3
Loans and leases, net of unearned discount	180	281
Gross charge-offs	17
Term Loans 2022 [Member] \| Current [Member] \| Residential [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	4,709	5,071
Term Loans 2022 [Member] \| Current [Member] \| Home Equity Lines and Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		1
Term Loans 2022 [Member] \| Current [Member] \| Recreational Finance [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		2,842
Term Loans 2022 [Member] \| Current [Member] \| Automobile [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	1,096	1,491
Term Loans 2022 [Member] \| Current [Member] \| Other [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		274
Term Loans 2021 [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	15,025	18,749
Gross charge-offs	47
Term Loans 2021 [Member] \| Residential [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due	88	51
Accruing Loans Past Due 90 Days or More	28	40
Nonaccrual	10	11
Loans and leases, net of unearned discount	3,858	4,104
Gross charge-offs	1
Term Loans 2021 [Member] \| Home Equity Lines and Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	2	2
Term Loans 2021 [Member] \| Recreational Finance [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	1,857
30-89 Days Past Due	19	10
Nonaccrual	8	7
Loans and leases, net of unearned discount	1,884	2,298
Gross charge-offs	14
Term Loans 2021 [Member] \| Automobile [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due	17	13
Nonaccrual	3	11
Loans and leases, net of unearned discount	1,067	1,582
Gross charge-offs	7
Term Loans 2021 [Member] \| Other [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	118
30-89 Days Past Due	2	1
Nonaccrual	1	1
Loans and leases, net of unearned discount	121	175
Gross charge-offs	7
Term Loans 2021 [Member] \| Current [Member] \| Residential [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	3,732	4,002
Term Loans 2021 [Member] \| Current [Member] \| Home Equity Lines and Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	2	2
Term Loans 2021 [Member] \| Current [Member] \| Recreational Finance [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		2,281
Term Loans 2021 [Member] \| Current [Member] \| Automobile [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	1,047	1,558
Term Loans 2021 [Member] \| Current [Member] \| Other [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		173
Term Loans 2020 [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	10,555	13,071
Gross charge-offs	31
Term Loans 2020 [Member] \| Residential [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due	52	40
Accruing Loans Past Due 90 Days or More	17	20
Nonaccrual	3	3
Loans and leases, net of unearned discount	2,615	2,780
Term Loans 2020 [Member] \| Home Equity Lines and Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	2	2
Term Loans 2020 [Member] \| Recreational Finance [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	1,286
30-89 Days Past Due	14	12
Nonaccrual	6	9
Loans and leases, net of unearned discount	1,306	1,609
Gross charge-offs	12
Term Loans 2020 [Member] \| Automobile [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due	9	7
Nonaccrual	2	7
Loans and leases, net of unearned discount	438	717
Gross charge-offs	3
Term Loans 2020 [Member] \| Other [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	33
Loans and leases, net of unearned discount	33	58
Gross charge-offs	3
Term Loans 2020 [Member] \| Current [Member] \| Residential [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	2,543	2,717
Term Loans 2020 [Member] \| Current [Member] \| Home Equity Lines and Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	2	2
Term Loans 2020 [Member] \| Current [Member] \| Recreational Finance [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		1,588
Term Loans 2020 [Member] \| Current [Member] \| Automobile [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	427	703
Term Loans 2020 [Member] \| Current [Member] \| Other [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		58
Term Loans 2019 [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	10,062	12,738
Gross charge-offs	142
Term Loans 2019 [Member] \| Residential [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due	28	22
Accruing Loans Past Due 90 Days or More	14	14
Nonaccrual	4	10
Loans and leases, net of unearned discount	1,261	1,439
Gross charge-offs	3
Term Loans 2019 [Member] \| Home Equity Lines and Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Nonaccrual		1
Loans and leases, net of unearned discount	13	16
Term Loans 2019 [Member] \| Recreational Finance [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	781
30-89 Days Past Due	11	8
Nonaccrual	5	8
Loans and leases, net of unearned discount	797	980
Gross charge-offs	9
Term Loans 2019 [Member] \| Automobile [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due	6	7
Nonaccrual	2	8
Loans and leases, net of unearned discount	206	394
Gross charge-offs	2
Term Loans 2019 [Member] \| Other [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	13
Loans and leases, net of unearned discount	13	39
Gross charge-offs	3
Term Loans 2019 [Member] \| Current [Member] \| Residential [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	1,215	1,393
Term Loans 2019 [Member] \| Current [Member] \| Home Equity Lines and Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	13	15
Term Loans 2019 [Member] \| Current [Member] \| Recreational Finance [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		964
Term Loans 2019 [Member] \| Current [Member] \| Automobile [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	198	379
Term Loans 2019 [Member] \| Current [Member] \| Other [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		39
Term Loans 2018 [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount		7,535
Term Loans 2018 [Member] \| Residential [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due		23
Accruing Loans Past Due 90 Days or More		14
Nonaccrual		5
Loans and leases, net of unearned discount		796
Term Loans 2018 [Member] \| Home Equity Lines and Loans [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due		1
Loans and leases, net of unearned discount		24
Term Loans 2018 [Member] \| Recreational Finance [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due		5
Nonaccrual		6
Loans and leases, net of unearned discount		498
Term Loans 2018 [Member] \| Automobile [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due		6
Nonaccrual		6
Loans and leases, net of unearned discount		179
Term Loans 2018 [Member] \| Other [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount		8
Term Loans 2018 [Member] \| Current [Member] \| Residential [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		754
Term Loans 2018 [Member] \| Current [Member] \| Home Equity Lines and Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		23
Term Loans 2018 [Member] \| Current [Member] \| Recreational Finance [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		487
Term Loans 2018 [Member] \| Current [Member] \| Automobile [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		167
Term Loans 2018 [Member] \| Current [Member] \| Other [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		8
Term Loans Prior Period [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	27,464	26,754
Gross charge-offs	190
Term Loans Prior Period [Member] \| Residential [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due	457	399
Accruing Loans Past Due 90 Days or More	205	245
Nonaccrual	179	231
Loans and leases, net of unearned discount	7,901	8,399
Gross charge-offs	4
Term Loans Prior Period [Member] \| Residential Limited Documentation [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due	31	22
Nonaccrual	55	78
Loans and leases, net of unearned discount	911	1,051
Gross charge-offs	2
Term Loans Prior Period [Member] \| Home Equity Lines and Loans [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due	3	2
Nonaccrual	5	6
Loans and leases, net of unearned discount	106	105
Term Loans Prior Period [Member] \| Recreational Finance [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	1,020
30-89 Days Past Due	16	11
Nonaccrual	9	12
Loans and leases, net of unearned discount	1,045	835
Gross charge-offs	16
Term Loans Prior Period [Member] \| Automobile [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due	5	4
Nonaccrual	2	6
Loans and leases, net of unearned discount	94	105
Gross charge-offs	3
Term Loans Prior Period [Member] \| Other [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	18
30-89 Days Past Due	1	1
Loans and leases, net of unearned discount	19	24
Gross charge-offs	10
Term Loans Prior Period [Member] \| Current [Member] \| Residential [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	7,060	7,524
Term Loans Prior Period [Member] \| Current [Member] \| Residential Limited Documentation [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	825	951
Term Loans Prior Period [Member] \| Current [Member] \| Home Equity Lines and Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	98	97
Term Loans Prior Period [Member] \| Current [Member] \| Recreational Finance [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		812
Term Loans Prior Period [Member] \| Current [Member] \| Automobile [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	$ 87	95
Term Loans Prior Period [Member] \| Current [Member] \| Other [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		$ 23

Pension Plans and Other Postretirement Benefits - Fair Values of Company's Pension Plan Assets by Asset Category (Detail) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	$ 3,141	$ 2,938
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	2,164	2,041
Significant Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	533	489
Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	444	408
Money-Market Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	65	90
Money-Market Investments [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	41	52
Money-Market Investments [Member] \| Significant Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	24	38
Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	1,449	1,343
Equity Securities [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	1,449	1,343
M&T Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	112	118
M&T Equity Securities [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	112	118
Domestic Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	512	450
Domestic Equity Securities [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	512	450
International Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	17	19
International Equity Securities [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	17	19
Domestic Mutual Fund Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	307	279
Domestic Mutual Fund Equity Securities [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	307	279
International Mutual Fund Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	501	477
International Mutual Fund Equity Securities [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	501	477
Total Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	959	873
Total Debt Securities [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	450	422
Total Debt Securities [Member] \| Significant Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	509	451
Corporate Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	227	200
Corporate Debt Securities [Member] \| Significant Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	227	200
Government Agency [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	276	236
Government Agency [Member] \| Significant Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	276	236
Non-U.S. Government [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	6	15
Non-U.S. Government [Member] \| Significant Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	6	15
Domestic Mutual Fund Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	450	422
Domestic Mutual Fund Debt Securities [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	450	422
Other Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	668	632
Other Securities [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	224	224
Other Securities [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	444	408
Other Diversified Mutual Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	110	108
Other Diversified Mutual Fund [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	110	108
Other Real Estate Partnerships [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	29	27
Other Real Estate Partnerships [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	7	7
Other Real Estate Partnerships [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	22	20
Other Private Equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	235	211
Other Private Equity [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	235	211
Other Hedge Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	285	276
Other Hedge Funds [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	107	109
Other Hedge Funds [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	178	167
Guaranteed Deposit Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	9	10
Guaranteed Deposit Fund [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	$ 9	$ 10

Investment Securities - Investment Ratings of All Privately Issued Mortgage-Backed Securities and Other Debt Securities (Detail) $ in Millions	Dec. 31, 2023 USD ($)
Obligations of States and Political Subdivisions [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Total securities with disclosed rating, Amortized Cost	$ 2,501
Total securities with disclosed rating, Estimated Fair Value	2,434
Obligations of States and Political Subdivisions [Member] \| A or Better [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Total securities with disclosed rating, Estimated Fair Value	2,426
Obligations of States and Political Subdivisions [Member] \| BBB [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Total securities with disclosed rating, Estimated Fair Value	1
Obligations of States and Political Subdivisions [Member] \| Not Rated [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Total securities with disclosed rating, Estimated Fair Value	7
Privately Issued [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Total securities with disclosed rating, Amortized Cost	42
Total securities with disclosed rating, Estimated Fair Value	46
Privately Issued [Member] \| B or Less [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Total securities with disclosed rating, Estimated Fair Value	1
Privately Issued [Member] \| Not Rated [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Total securities with disclosed rating, Estimated Fair Value	45
Other Debt Securities [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Total securities with disclosed rating, Amortized Cost	178
Total securities with disclosed rating, Estimated Fair Value	167
Other Debt Securities [Member] \| A or Better [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Total securities with disclosed rating, Estimated Fair Value	8
Other Debt Securities [Member] \| BBB [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Total securities with disclosed rating, Estimated Fair Value	73
Other Debt Securities [Member] \| BB [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Total securities with disclosed rating, Estimated Fair Value	31
Other Debt Securities [Member] \| Not Rated [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Total securities with disclosed rating, Estimated Fair Value	$ 55