Document and Entity Information - USD ($)	12 Months Ended
Document and Entity Information - USD ($)	Dec. 31, 2019	Jan. 31, 2020	Jun. 30, 2019
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2019
Document Fiscal Year Focus	2019
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			$ 22,178,197,910
Entity Common Stock, Shares Outstanding		130,436,633
Entity Shell Company	false
Entity Small Business	false
Entity Emerging Growth Company	false
Title of 12(b) Security	Common Stock, $.50 par value
Trading Symbol	MTB
Security Exchange Name	NYSE
Entity File Number	1-9861
Entity Incorporation, State or Country Code	NY
Entity Tax Identification Number	16-0968385
Entity Address, Address Line One	One M&T Plaza
Entity Address, City or Town	Buffalo
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
Documents Incorporated by Reference [Text Block]	(1) Portions of the Proxy Statement for the 2020 Annual Meeting of Shareholders of M&T Bank Corporation in Parts II and III.

Consolidated Balance Sheet - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Assets
Cash and due from banks	$ 1,432,805	$ 1,605,439
Interest-bearing deposits at banks	7,190,154	8,105,197
Federal funds sold	3,500
Trading account	470,129	185,584
Investment securities (includes pledged securities that can be sold or repledged of $200,339 at December 31, 2019; $487,365 at December 31, 2018)
Available for sale (cost: $6,258,276 at December 31, 2019; $8,869,423 at December 31, 2018)	6,318,776	8,682,509
Held to maturity (fair value: $2,699,206 at December 31, 2019; $3,255,483 at December 31, 2018)	2,656,917	3,316,640
Equity and other securities (cost: $487,041 at December 31, 2019; $677,187 at December 31, 2018)	521,558	693,664
Total investment securities	9,497,251	12,692,813
Loans and leases	91,188,525	88,733,492
Unearned discount	(265,656)	(267,015)
Loans and leases, net of unearned discount	90,922,869	88,466,477
Allowance for credit losses	(1,051,071)	(1,019,444)
Loans and leases, net	89,871,798	87,447,033
Premises and equipment	1,140,924	647,408
Goodwill	4,593,112	4,593,112
Core deposit and other intangible assets	29,034	47,067
Accrued interest and other assets	5,644,050	4,773,750
Total assets	119,872,757	120,097,403
Liabilities
Noninterest-bearing deposits	32,396,407	32,256,668
Savings and interest-checking deposits	54,932,162	50,963,744
Time deposits	5,757,456	6,124,254
Deposits at Cayman Islands office	1,684,044	811,906
Total deposits	94,770,069	90,156,572
Short-term borrowings	62,363	4,398,378
Accrued interest and other liabilities	2,337,490	1,637,348
Long-term borrowings	6,986,186	8,444,914
Total liabilities	104,156,108	104,637,212
Shareholders' equity
Preferred stock, $1.00 par, 1,000,000 shares authorized; Issued and outstanding: Liquidation preference of $1,000 per share: 350,000 shares at December 31, 2019 and 731,500 shares at December 31, 2018; Liquidation preference of $10,000 per share: 90,000 shares at December 31, 2019 and 50,000 shares at December 31, 2018	1,250,000	1,231,500
Common stock, $.50 par, 250,000,000 shares authorized, 159,741,898 shares issued at December 31, 2019; 159,765,044 shares issued at December 31, 2018	79,871	79,883
Common stock issuable, 21,534 shares at December 31, 2019; 24,563 shares at December 31, 2018	1,566	1,726
Additional paid-in capital	6,593,539	6,579,342
Retained earnings	12,820,916	11,516,672
Accumulated other comprehensive income (loss), net	(206,680)	(420,081)
Treasury stock — common, at cost — 29,174,402 shares at December 31, 2019; 21,255,275 shares at December 31, 2018	(4,822,563)	(3,528,851)
Total shareholders’ equity	15,716,649	15,460,191
Total liabilities and shareholders’ equity	$ 119,872,757	$ 120,097,403

Consolidated Balance Sheet (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Pledged securities that can be sold or repledged	$ 200,339	$ 487,365
Investment securities, available for sale, amortized cost	6,258,276	8,869,423
Investment securities, held to maturity, fair value	2,699,206	3,255,483
Equity and other securities, cost	$ 487,041	$ 677,187
Preferred stock, par value	$ 1.00	$ 1.00
Preferred stock, shares authorized	1,000,000	1,000,000
Common stock, par value	$ 0.50	$ 0.50
Common stock, shares authorized	250,000,000	250,000,000
Common stock, shares issued	159,741,898	159,765,044
Common stock issuable, shares	21,534	24,563
Treasury stock, common shares	29,174,402	21,255,275
Series A Series C Series And E Preferred Stock [Member]
Preferred stock, shares issued	350,000	731,500
Preferred stock, shares outstanding	350,000	731,500
Preferred stock, liquidation preference per share	$ 1,000	$ 1,000
Series F And Series G Preferred Stock [Member]
Preferred stock, shares issued	90,000	50,000
Preferred stock, shares outstanding	90,000	50,000
Preferred stock, liquidation preference per share	$ 10,000	$ 10,000

Consolidated Statement of Income - USD ($) $ in Thousands	12 Months Ended
Consolidated Statement of Income - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Interest income
Loans and leases, including fees	$ 4,442,182	$ 4,164,561	$ 3,742,867
Investment securities
Fully taxable	288,532	323,912	361,157
Exempt from federal taxes	321	665	1,431
Deposits at banks	141,397	108,182	61,326
Other	7,161	1,391	1,014
Total interest income	4,879,593	4,598,711	4,167,795
Interest expense
Savings and interest-checking deposits	368,003	215,411	133,177
Time deposits	95,426	51,423	61,505
Deposits at Cayman Islands office	21,917	5,633	1,186
Short-term borrowings	24,741	5,386	1,511
Long-term borrowings	239,242	248,556	189,372
Total interest expense	749,329	526,409	386,751
Net interest income	4,130,264	4,072,302	3,781,044
Provision for credit losses	176,000	132,000	168,000
Net interest income after provision for credit losses	3,954,264	3,940,302	3,613,044
Other income
Brokerage services income	48,922	51,069	61,445
Trading account and foreign exchange gains	62,044	32,547	35,301
Gain (loss) on bank investment securities	18,037	(6,301)	21,279
Other revenues from operations	469,320	451,321	440,538
Total other income	2,061,679	1,856,000	1,851,143
Other expense
Salaries and employee benefits	1,900,797	1,752,264	1,648,794
Equipment and net occupancy	324,079	298,828	295,084
Outside data processing and software	229,731	199,025	184,670
FDIC assessments	41,535	68,526	101,871
Advertising and marketing	93,472	85,710	69,203
Printing, postage and supplies	39,893	35,658	35,960
Amortization of core deposit and other intangible assets	19,490	24,522	31,366
Other costs of operations	819,685	823,529	773,377
Total other expense	3,468,682	3,288,062	3,140,325
Income before taxes	2,547,261	2,508,240	2,323,862
Income taxes	618,112	590,160	915,556
Net income	1,929,149	1,918,080	1,408,306
Net income available to common shareholders
Basic	1,849,509	1,836,028	1,327,503
Diluted	$ 1,849,511	$ 1,836,035	$ 1,327,517
Net income per common share
Basic	$ 13.76	$ 12.75	$ 8.72
Diluted	$ 13.75	$ 12.74	$ 8.70
Mortgage Banking Revenues [Member]
Other income
Revenue from contract with customer	$ 457,770	$ 360,442	$ 363,827
Service Charges on Deposit Accounts [Member]
Other income
Revenue from contract with customer	432,978	429,337	427,372
Trust Income [Member]
Other income
Revenue from contract with customer	$ 572,608	$ 537,585	$ 501,381

Consolidated Statement of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement Of Partners Capital [Abstract]
Net income	$ 1,929,149	$ 1,918,080	$ 1,408,306
Other comprehensive income (loss), net of tax and reclassification adjustments:
Net unrealized gains (losses) on investment securities	184,906	(86,523)	(19,766)
Cash flow hedges adjustments	108,520	6,091	(9,912)
Foreign currency translation adjustments	1,091	(2,225)	2,241
Defined benefit plans liability adjustments	(81,116)	43,243	22,288
Total other comprehensive income (loss)	213,401	(39,414)	(5,149)
Total comprehensive income	$ 2,142,550	$ 1,878,666	$ 1,403,157

- Definition

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

+ References + Details

Consolidated Statement of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities
Net income	$ 1,929,149	$ 1,918,080	$ 1,408,306
Adjustments to reconcile net income to net cash provided by operating activities
Provision for credit losses	176,000	132,000	168,000
Depreciation and amortization of premises and equipment	209,937	104,864	109,587
Amortization of capitalized servicing rights	71,888	49,619	56,172
Amortization of core deposit and other intangible assets	19,490	24,522	31,366
Provision for deferred income taxes	57,548	15,857	400,790
Asset write-downs	7,701	24,774	15,429
Net (gain) loss on sales of assets	31,526	(23,503)	(53,467)
Net change in accrued interest receivable, payable	30,923	(7,162)	(17,896)
Net change in other accrued income and expense	75,930	13,436	(201,981)
Net change in loans originated for sale	130,230	(150,695)	711,657
Net change in trading account assets and liabilities	(382,767)	(11,940)	153,972
Net cash provided by operating activities	2,357,555	2,089,852	2,781,935
Cash flows from investing activities
Proceeds from sales of investment securities Available for sale	107	418	534,160
Proceeds from sales of investment securities equity and other	1,169,876	650,858	178,468
Proceeds from maturities of investment securities Available for sale	2,621,603	1,997,263	2,131,118
Proceeds from maturities of investment securities Held to maturity	1,162,820	478,172	528,585
Purchases of investment securities Available for sale	(28,120)	(12,494)	(251,185)
Purchases of investment securities Held to maturity	(495,277)	(444,703)	(1,425,690)
Purchases of investment securities equity and other	(979,734)	(834,856)	(132,378)
Net (increase) decrease in loans and leases	(2,795,263)	(475,895)	1,931,492
Net (increase) decrease in interest-bearing deposits at banks	915,043	(3,026,294)	(78,265)
Capital expenditures, net	(178,049)	(97,676)	(78,966)
Net (increase) decrease in loan servicing advances	(470,078)	307,252	37,761
Other, net	(195,921)	47,904	19,825
Net cash provided (used) by investing activities	727,007	(1,410,051)	3,394,925
Cash flows from financing activities
Net increase (decrease) in deposits	4,616,082	(2,272,505)	(3,075,322)
Net increase (decrease) in short-term borrowings	(4,336,015)	4,223,279	11,657
Proceeds from long-term borrowings		1,773,189	2,145,950
Payments on long-term borrowings	(1,553,493)	(1,459,081)	(3,433,440)
Purchases of treasury stock	(1,349,785)	(2,194,396)	(1,205,905)
Dividends paid — common	(552,138)	(510,382)	(457,402)
Dividends paid — preferred	(67,454)	(72,521)	(72,734)
Redemption of Series A and Series C preferred stock	(381,500)
Other, net	(25,393)	17,167	10,675
Net cash used by financing activities	(3,253,696)	(495,250)	(6,076,521)
Net increase (decrease) in cash, cash equivalents and restricted cash	(169,134)	184,551	100,339
Cash, cash equivalents and restricted cash at beginning of period	1,605,439	1,420,888	1,320,549
Cash, cash equivalents and restricted cash at end of period	1,436,305	1,605,439	1,420,888
Supplemental disclosure of cash flow information
Interest received during the period	4,892,301	4,568,991	4,155,723
Interest paid during the period	735,787	516,230	405,290
Income taxes paid during the period	320,513	375,116	494,205
Supplemental schedule of noncash investing and financing activities
Real estate acquired in settlement of loans	90,072	72,408	121,292
Securitization of residential mortgage loans allocated to Available-for-sale investment securities	5,379	22,448	36,747
Securitization of residential mortgage loans allocated to capitalized servicing rights	83	$ 365	$ 422
Adoption of lease accounting standard - Right-of-use assets	393,877
Adoption of lease accounting standard - Other liabilities	398,810
Additions to right-of-use assets under operating leases	132,219
Series G Preferred Stock [Member]
Cash flows from financing activities
Proceeds from issuance of Series G preferred stock	$ 396,000

Consolidated Statement of Changes in Shareholders' Equity - USD ($)
$ in Thousands

Total

Series A And Series C [Member]

Series G Preferred Stock [Member]

Preferred Stock [Member]

Series A And Series C [Member]

Preferred Stock [Member]

Series G Preferred Stock [Member]

Common Stock [Member]

Common Stock Issuable [Member]

Additional Paid-in Capital [Member]

Series G Preferred Stock [Member]

Additional Paid-in Capital [Member]

Series A Warrants [Member]

Retained Earnings [Member]

Accumulated Other Comprehensive Income (Loss), Net [Member]

Treasury Stock [Member]

Series A Warrants [Member]

Beginning balance at Dec. 31, 2016

$ 16,486,622

$ 1,231,500

$ 79,973

$ 2,145

$ 6,676,948

$ 9,222,488

$ (294,636)

$ (431,796)

Total comprehensive income

1,403,157

1,408,306

(5,149)

Reclassification of income tax effects to retained earnings

64,029

(64,029)

Preferred stock cash dividends

(72,734)

Exercise of stock warrants into common stock

$ (28,746)

$ 28,746

Purchases of treasury stock

(1,205,905)

Stock-based compensation transactions, net

96,879

(64)

(298)

(57,347)

(85)

154,673

Common stock cash dividends

(457,200)

Ending balance at Dec. 31, 2017

16,250,819

1,231,500

79,909

1,847

6,590,855

10,164,804

(363,814)

(1,454,282)

Cumulative effect of change inaccounting principle — equity securities

(16,853)

^[1]

16,853

(16,853)

Total comprehensive income

1,878,666

1,918,080

(39,414)

Preferred stock cash dividends

(72,521)

Exercise of stock warrants into common stock

$ (22,394)

$ 22,394

Purchases of treasury stock

(2,194,396)

Stock-based compensation transactions, net

108,081

(26)

(121)

10,881

(86)

97,433

Common stock cash dividends

(510,458)

Ending balance at Dec. 31, 2018

15,460,191

1,231,500

79,883

1,726

6,579,342

11,516,672

(420,081)

(3,528,851)

Total comprehensive income

2,142,550

1,929,149

213,401

Preferred stock cash dividends

(72,482)

Redemption of Series A and Series C preferred stock

$ (381,500)

Issuance of Series G preferred stock

$ 396,000

$ 400,000

$ (4,000)

Purchases of treasury stock

(1,349,785)

Stock-based compensation transactions, net

73,891

(12)

(160)

18,197

(207)

56,073

Common stock cash dividends

(552,216)

Ending balance at Dec. 31, 2019

$ 15,716,649

$ 1,250,000

$ 79,871

$ 1,566

$ 6,593,539

$ 12,820,916

$ (206,680)

$ (4,822,563)

[1]

Beginning January 1, 2018, equity securities with readily determinable market values are required to be measured at fair value with changes in fair value recognized in the income statement. Prior to that date, such changes in fair value were reflected in other comprehensive income. Separate presentation of investment securities with an other-than-temporary impairment change is no longer required.

Significant accounting policies

12 Months Ended

Dec. 31, 2019

Accounting Policies [Abstract]

Significant accounting policies

1. Significant accounting policies

M&T Bank Corporation (“M&T”) is a bank holding company 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, trust, mortgage banking, asset management, insurance and other financial services. Banking activities are largely focused on consumers residing in New York State, Maryland, New Jersey, Pennsylvania, Delaware, Connecticut, 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 M&T and subsidiaries (“the Company”) are in accordance with accounting principles generally accepted in the United States of America (“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. The 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 25 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 19.

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 foreign exchange 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.”

Investments in equity securities having readily determinable fair values are stated at fair value and, beginning in 2018, 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. Prior to 2018, equity securities with readily determinable fair values were classified as available for sale. Amortization of premiums and accretion of discounts for investment securities available for sale and held to maturity are included in interest income.

Other securities are stated at cost and include stock of the Federal Reserve Bank of New York and the Federal Home Loan Bank (“FHLB”) of New York.

Individual debt securities are written down through a charge to earnings when declines in value below the cost basis of a security are considered to be other than temporary. In cases where fair value is less than amortized cost and the Company intends to sell a debt security, it is more likely than not to be required to sell a debt security before recovery of its amortized cost basis, or the Company does not expect to recover the entire amortized cost basis of a debt security, an other-than-temporary impairment is considered to have occurred. If the Company intends to sell the debt security or more likely than not will be required to sell the security before recovery of its amortized cost basis, the other-than-temporary impairment is recognized in earnings equal to the entire difference between the debt security’s amortized cost basis and its fair value. If the Company does not expect to recover the entire amortized cost basis of the security, the Company does not intend to sell the security and it is not more likely than not that the Company will be required to sell the security before recovery of its amortized cost basis, the other-than-temporary impairment is separated into (a) the amount representing the credit loss and (b) the amount related to all other factors. The amount of the other-than-temporary impairment related to the credit loss is recognized in earnings while the amount related to other factors is recognized in other comprehensive income, net of applicable taxes. Subsequently, the Company accounts for the other-than-temporarily impaired debt security as if the security had been purchased on the measurement date of the other-than-temporary impairment at an amortized cost basis equal to the previous amortized cost basis less the other-than-temporary impairment 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 depends on whether the loans were originated by the Company or were acquired in a business combination.

Originated loans and leases

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 principal or interest is delinquent 90 days, unless management determines that the loan status clearly warrants other treatment. Nonaccrual commercial 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. 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. 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. Loan balances are charged off when it becomes evident that such balances are not fully collectible. For commercial 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 collectible. 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. 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. 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 market 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.”

Except for consumer and residential mortgage loans that are considered smaller balance homogenous loans and are evaluated collectively, the Company considers a loan to be impaired for purposes of applying GAAP when, based on current information and events, it is probable that the Company will be unable to collect all amounts according to the contractual terms of the loan agreement or the loan is delinquent 90 days. Regardless of loan type, the Company considers a loan to be impaired if it qualifies as a troubled debt restructuring. Impaired loans are classified as either nonaccrual or as loans renegotiated at below market rates which continue to accrue interest, provided that a credit assessment of the borrower’s financial condition results in an expectation of full repayment under the modified contractual terms. Certain loans greater than 90 days delinquent are not considered impaired 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 are generally not considered impaired. Impairment of a loan is measured based on the present value of expected future cash flows discounted at the loan’s effective interest rate, the loan’s observable market price, or the fair value of collateral if the loan is collateral-dependent. Interest received on impaired loans placed on nonaccrual status is generally applied to reduce the carrying value of the loan or, if principal is considered fully collectible, recognized as interest income.

Residual value estimates for commercial leases are generally determined through internal or external reviews of the leased property. The Company reviews commercial lease residual values at least annually and recognizes residual value impairments deemed to be other than temporary.

Loans and leases acquired in a business combination

Loans acquired in a business combination subsequent to December 31, 2008 were initially recorded at fair value with no carry-over of an acquired entity’s previously established allowance for credit losses. Purchased impaired loans represent specifically identified loans with evidence of credit deterioration for which it was probable at acquisition that the Company would be unable to collect all contractual principal and interest payments. For purchased impaired loans and other loans acquired at a discount that was, in part, attributable to credit quality, the excess of cash flows expected at acquisition over the estimated fair value of acquired loans was recognized as interest income over the remaining lives of the loans. Subsequent decreases in the expected cash flows required the Company to evaluate the need for additions to the Company’s allowance for credit losses. Subsequent improvements in expected cash flows resulted first in the recovery of any related allowance for credit losses and then in recognition of additional interest income over the then-remaining lives of the 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 represents, in management’s judgment, the amount of losses inherent in the loan and lease portfolio as of the balance sheet date. The allowance is determined by management’s evaluation of the loan and lease portfolio based on such factors as the differing economic risks associated with each loan category, the current financial condition of specific borrowers, the economic environment in which borrowers operate, the level of delinquent loans, the value of any collateral and, where applicable, the existence of any guarantees or indemnifications. The effects of probable decreases in expected principal cash flows on loans acquired at a discount are also considered in the establishment of the allowance for credit losses.

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 “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 residential real estate property collateralizing a consumer mortgage loan upon either (1) the creditor obtaining legal title to the residential real estate property upon completion of a foreclosure or (2) the borrower conveying all interest in the residential 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 “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 typically 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.

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 of five to ten 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 (a) a hedge of the exposure to changes in the fair value of a recognized asset or liability or an unrecognized firm commitment, (b) a hedge of the exposure to variable cash flows of a forecasted transaction or (c) 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, beginning in 2018, 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. Prior to 2018, hedge ineffectiveness for fair value and cash flow hedges was recorded in “other revenues from operations” in the consolidated statement of income. In addition, for cash flow hedges, the effective portion of the derivative’s unrealized gain or loss was initially recorded as a component of other comprehensive income and subsequently reclassified into earnings when the forecasted transaction affected 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.

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 trading account assets or liabilities with resultant changes in fair value being recognized in “trading account and foreign exchange gains” in the consolidated statement of income.

Stock-based compensation

Stock-based compensation expense is recognized over the vesting period of the stock-based grant based on the estimated grant date value of the stock-based compensation, 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.

Investment securities

12 Months Ended

Dec. 31, 2019

Investments Debt And Equity Securities [Abstract]

Investment securities

2. Investment securities

On January 1, 2018, the Company adopted amended guidance requiring equity investments with readily determinable fair values to be measured at fair value with changes in fair value recognized in the consolidated statement of income. This amended guidance excludes equity method investments, investments in consolidated subsidiaries, exchange membership ownership interests, and Federal Home Loan Bank of New York and Federal Reserve Bank of New York capital stock. Upon adoption the Company reclassified $17 million, after-tax effect, from accumulated other comprehensive income to retained earnings, representing the difference between fair value and the cost basis of equity investments with readily determinable fair values at January 1, 2018. The amortized cost and estimated fair value of investment securities were as follows:

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
	(In thousands)
December 31, 2019
Investment securities available for sale:
U.S. Treasury and federal agencies	$	9,742	$	41	$	16	$	9,767
Obligations of states and political subdivisions		776		2		3		775
Mortgage-backed securities:
Government issued or guaranteed		6,113,913		88,634		21,607		6,180,940
Privately issued		16		—		—		16
Other debt securities		133,829		2,046		8,597		127,278
		6,258,276		90,723		30,223		6,318,776
Investment securities held to maturity:
U.S. Treasury and federal agencies		249,862		286		—		250,148
Obligations of states and political subdivisions		4,140		16		—		4,156
Mortgage-backed securities:
Government issued or guaranteed		2,306,180		50,381		1,992		2,354,569
Privately issued		93,496		11,779		18,181		87,094
Other debt securities		3,239		—		—		3,239
		2,656,917		62,462		20,173		2,699,206
Total debt securities	$	8,915,193	$	153,185	$	50,396	$	9,017,982
Equity and other securities:
Readily marketable equity — at fair value	$	105,524	$	34,786	$	269	$	140,041
Other — at cost		381,517		—		—		381,517
Total equity and other securities	$	487,041	$	34,786	$	269	$	521,558

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
	(In thousands)
December 31, 2018
Investment securities available for sale:
U.S. Treasury and federal agencies	$	1,346,782	$	—	$	9,851	$	1,336,931
Obligations of states and political subdivisions		1,660		4		5		1,659
Mortgage-backed securities:
Government issued or guaranteed		7,383,340		15,754		182,103		7,216,991
Privately issued		24		—		2		22
Other debt securities		137,617		770		11,481		126,906
		8,869,423		16,528		203,442		8,682,509
Investment securities held to maturity:
U.S. Treasury and federal agencies		446,542		—		239		446,303
Obligations of states and political subdivisions		7,494		22		12		7,504
Mortgage-backed securities:
Government issued or guaranteed		2,745,776		4,165		55,111		2,694,830
Privately issued		113,160		12,345		22,327		103,178
Other debt securities		3,668		—		—		3,668
		3,316,640		16,532		77,689		3,255,483
Total debt securities	$	12,186,063	$	33,060	$	281,131	$	11,937,992
Equity and other securities:
Readily marketable equity — at fair value	$	77,440	$	17,295	$	818	$	93,917
Other — at cost		599,747		—		—		599,747
Total equity and other securities	$	677,187	$	17,295	$	818	$	693,664

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, 2019.

As of December 31, 2019, 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
	Amortized Cost		Estimated Fair Value		A or Better		BBB		BB		B or Less		Not Rated
	(In thousands)

Obligations of states and political subdivisions	$	4,916	$	4,931	$	4,809	$	122	$	—	$	—	$	—
Privately issued mortgage-backed securities		93,512		87,110		8,015		8,768		—		20,671		49,656
Other debt securities		137,068		130,517		4,740		74,770		19,106		—		31,901
Total	$	235,496	$	222,558	$	17,564	$	83,660	$	19,106	$	20,671	$	81,557

The amortized cost and estimated fair value of collateralized mortgage obligations included in mortgage-backed securities were as follows:

	December 31
	2019		2018
	(In thousands)
Collateralized mortgage obligations:
Amortized cost	$	94,817	$	115,171
Estimated fair value		88,410		105,155

Gross realized gains on investment securities were $23 million in 2017. During 2017, the Company sold a portion of its Fannie Mae and Freddie Mac preferred stock holdings held in the available-for-sale investment securities portfolio for a gain of $18 million. There were no significant gross realized gains or losses from sales of investment securities in 2019 or 2018. There were no significant gross realized losses from sales of investment securities in 2017.

At December 31, 2019, the amortized cost and estimated fair value of debt securities by contractual maturity were as follows:

	Amortized Cost		Estimated Fair Value
	(In thousands)
Debt securities available for sale:
Due in one year or less	$	4,418		4,427
Due after one year through five years		10,717		10,777
Due after five years through ten years		99,212		98,616
Due after ten years		30,000		24,000
		144,347		137,820
Mortgage-backed securities available for sale		6,113,929		6,180,956
	$	6,258,276		6,318,776
Debt securities held to maturity:
Due in one year or less	$	251,457		251,749
Due after one year through five years		2,545		2,555
Due after ten years		3,239		3,239
		257,241		257,543
Mortgage-backed securities held to maturity		2,399,676		2,441,663
	$	2,656,917		2,699,206

A summary of investment securities that as of December 31, 2019 and 2018 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
	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
	(In thousands)
December 31, 2019
Investment securities available for sale:
U.S. Treasury and federal agencies	$	1,406		(7	)		2,893		(9	)
Obligations of states and political subdivisions		—		—			277		(3	)
Mortgage-backed securities:
Government issued or guaranteed		117,299		(222	)		2,002,364		(21,385	)
Other debt securities		6,600		(354	)		56,313		(8,243	)
		125,305		(583	)		2,061,847		(29,640	)
Investment securities held to maturity:
Mortgage-backed securities:
Government issued or guaranteed		2,727		(5	)		145,235		(1,987	)
Privately issued		—		—			49,656		(18,181	)
		2,727		(5	)		194,891		(20,168	)
Total	$	128,032		(588	)		2,256,738		(49,808	)

December 31, 2018
Investment securities available for sale:
U.S. Treasury and federal agencies	$	273		(2	)		1,335,559		(9,849	)
Obligations of states and political subdivisions		629		(5	)		—		—
Mortgage-backed securities:
Government issued or guaranteed		405,558		(2,892	)		5,646,773		(179,211	)
Privately issued		22		(2	)		—		—
Other debt securities		53,478		(2,187	)		66,014		(9,294	)
		459,960		(5,088	)		7,048,346		(198,354	)
Investment securities held to maturity:
U.S. Treasury and federal agencies		446,303		(239	)		—		—
Obligations of states and political subdivisions		—		—			3,126		(12	)
Mortgage-backed securities:
Government issued or guaranteed		179,354		(989	)		2,082,723		(54,122	)
Privately issued		—		—			51,943		(22,327	)
		625,657		(1,228	)		2,137,792		(76,461	)
Total	$	1,085,617		(6,316	)		9,186,138		(274,815	)

The Company owned 641 individual investment securities with aggregate gross unrealized losses of $50 million at December 31, 2019. Based on a review of each of the securities in the investment securities portfolio at December 31, 2019, the Company concluded that it expected to recover the amortized cost basis of its investment. As of December 31, 2019, 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, 2019, the Company has not identified events or changes in circumstances which may have a significant adverse effect on the fair value of the $382 million of cost method investment securities.

At December 31, 2019, investment securities with a carrying value of $1.9 billion, including $1.5 billion of investment securities available for sale, were pledged to secure borrowings from various FHLBs, repurchase agreements, governmental deposits, interest rate swap agreements and available lines of credit as described in note 8.

Investment securities pledged by the Company to secure obligations whereby the secured party is permitted by contract or custom to sell or repledge such collateral totaled $200 million at December 31, 2019. The pledged securities included securities of the U.S. Treasury and federal agencies and mortgage-backed securities.

Loans and leases

12 Months Ended

Dec. 31, 2019

Receivables [Abstract]

Loans and leases

3. Loans and leases

Total loans and leases outstanding were comprised of the following:

	December 31
	2019			2018
	(In thousands)
Loans
Commercial, financial, etc.	$	22,575,700		$	21,730,012
Real estate:
Residential		16,098,125			17,150,658
Commercial		26,718,325			25,666,200
Construction		9,010,297			8,823,635
Consumer		15,373,881			13,956,086
Total loans		89,776,328			87,326,591
Leases
Commercial		1,412,197			1,406,901
Total loans and leases		91,188,525			88,733,492
Less: unearned discount		(265,656	)		(267,015	)
Total loans and leases, net of unearned discount	$	90,922,869		$	88,466,477

One-to-four family residential mortgage loans held for sale were $414 million at December 31, 2019 and $205 million at December 31, 2018. Commercial real estate loans held for sale were $28 million at December 31, 2019 and $347 million at December 31, 2018.

As of December 31, 2019, approximately $3.9 billion of commercial real estate loan balances serviced for others had been sold with recourse in conjunction with the Company’s participation in the Fannie Mae Delegated Underwriting and Servicing (“DUS”) program. At December 31, 2019, 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.

In addition to recourse obligations, as described in note 21, 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. Charges incurred for such obligation were not material in 2019, 2018 or 2017.

A summary of current, past due and nonaccrual loans as of December 31, 2019 and 2018 follows:

	Current		30-89 Days Past Due		Accruing Loans Past Due 90 Days or More (a)		Accruing Loans Acquired at a Discount Past Due 90 days or More (b)		Purchased Impaired (c)		Nonaccrual		Total
	(In thousands)
December 31, 2019
Commercial, financial, leasing, etc.	$	23,290,797		184,011		16,776		27		—		346,557	$	23,838,168
Real estate:
Commercial		26,311,414		165,579		6,740		—		15,601		158,474		26,657,808
Residential builder and developer		1,521,315		21,195		—		—		753		3,982		1,547,245
Other commercial construction		7,204,148		95,346		3,360		—		1,237		32,770		7,336,861
Residential		12,760,040		451,274		486,515		5,788		143,145		235,663		14,082,425
Residential — limited documentation		1,858,037		65,215		181		—		66,809		83,427		2,073,669
Consumer:
Home equity lines and loans		4,386,511		30,229		—		1,662		—		63,215		4,481,617
Recreational finance		5,484,997		36,827		—		99		—		14,219		5,536,142
Automobile		3,787,221		78,478		—		—		—		21,293		3,886,992
Other		1,395,240		45,978		5,156		32,056		—		3,512		1,481,942
Total	$	87,999,720		1,174,132		518,728		39,632		227,545		963,112	$	90,922,869

December 31, 2018
Commercial, financial, leasing, etc.	$	22,701,020		39,798		2,567		168		—		234,423	$	22,977,976
Real estate:
Commercial		25,250,983		134,474		11,457		10		9,769		203,672		25,610,365
Residential builder and developer		1,665,178		20,333		—		—		—		4,798		1,690,309
Other commercial construction		6,982,077		43,615		14,344		—		641		22,205		7,062,882
Residential		13,591,790		404,808		189,682		6,650		203,044		233,352		14,629,326
Residential — limited documentation		2,278,040		72,544		—		—		89,851		84,685		2,525,120
Consumer:
Home equity lines and loans		4,758,513		25,416		—		5,033		—		71,292		4,860,254
Recreational finance		4,085,781		29,947		—		235		—		11,199		4,127,162
Automobile		3,555,757		79,804		—		—		—		23,359		3,658,920
Other		1,271,811		15,598		4,477		27,654		—		4,623		1,324,163
Total	$	86,140,950		866,337		222,527		39,750		303,305		893,608	$	88,466,477

(a)	Excludes loans acquired at a discount.

(b)	Loans acquired at a discount that were recorded at fair value at acquisition date. This category does not include purchased impaired loans that are presented separately.

(c)	Accruing loans acquired at a discount that were impaired at acquisition date and recorded at fair value.

If nonaccrual and renegotiated loans had been accruing interest at their originally contracted terms, interest income on such loans would have amounted to $68 million in 2019, $69 million in 2018 and $64 million in 2017. The actual amounts included in interest income on such loans were $33 million in each of 2019 and 2018 and $31 million in 2017.

The outstanding principal balance and the carrying amount of loans acquired at a discount that were recorded at fair value at the acquisition date and included in the consolidated balance sheet were as follows:

	December 31
	2019		2018
	(In thousands)

Outstanding principal balance	$	769,414	$	1,016,785
Carrying amount:
Commercial, financial, leasing, etc.		21,114		27,073
Commercial real estate		94,890		135,047
Residential real estate		341,807		473,511
Consumer		77,785		91,860
	$	535,596	$	727,491

Purchased impaired loans included in the table above totaled $228 million at December 31, 2019 and $303 million at December 31, 2018, representing less than 1% of the Company’s assets as of each date. A summary of changes in the accretable yield for loans acquired at a discount for the years ended December 31, 2019, 2018 and 2017 follows:

For the Year Ended December 31,	2019						2018						2017
	Purchased Impaired			Other Acquired			Purchased Impaired			Other Acquired			Purchased Impaired			Other Acquired
	(In thousands)

Balance at beginning of period	$	147,210		$	96,907		$	157,918		$	133,162		$	154,233		$	201,153
Interest income		(49,017	)		(36,452	)		(37,819	)		(63,856	)		(47,452	)		(82,605	)
Reclassifications from nonaccretable balance		36,718			15,534			27,111			22,849			51,137			16,437
Other (a)		—			(3,909	)		—			4,752			—			(1,823	)
Balance at end of period	$	134,911		$	72,080		$	147,210		$	96,907		$	157,918		$	133,162

(a)	Other changes in expected cash flows including changes in interest rates and prepayment assumptions.

During the normal course of business, the Company modifies loans to maximize recovery efforts. If the borrower is experiencing financial difficulty and a concession is granted, the Company considers such modifications as troubled debt restructurings and classifies those loans as either nonaccrual loans or renegotiated loans. The types of concessions that the Company grants typically include principal deferrals and interest rate concessions, but may also include other types of concessions.

The tables that follow summarize the Company’s loan modification activities that were considered troubled debt restructurings for the years ended December 31, 2019, 2018 and 2017:

					Post-modification (a)
Year Ended December 31, 2019	Number		Pre- modification Recorded Investment		Principal Deferral		Interest Rate Reduction		Other		Combination of Concession Types		Total
	(Dollars in thousands)

Commercial, financial, leasing, etc.		150	$	63,715	$	10,485	$	—	$	—	$	52,871	$	63,356
Real estate:
Commercial		51		48,315		5,193		—		—		26,152		31,345
Residential builder and developer		2		1,330		1,068		—		—		—		1,068
Other commercial construction		3		1,559		—		—		—		1,500		1,500
Residential		83		21,695		10,819		—		—		11,907		22,726
Residential — limited documentation		6		1,409		399		—		—		1,044		1,443
Consumer:
Home equity lines and loans		41		4,127		176		—		—		4,004		4,180
Recreational finance		10		265		265		—		—		—		265
Automobile		66		1,141		1,076		—		—		65		1,141
Total		412	$	143,556	$	29,481	$	—	$	—	$	97,543	$	127,024

Year Ended December 31, 2018

Commercial, financial, leasing, etc.		203	$	102,445	$	50,490	$	803	$	6,210	$	45,411	$	102,914
Real estate:
Commercial		83		30,217		16,870		175		4,686		9,000		30,731
Other commercial construction		1		752		746		—		—		—		746
Residential		134		34,798		19,962		—		—		18,110		38,072
Residential — limited documentation		9		1,887		827		—		—		1,423		2,250
Consumer:
Home equity lines and loans		47		3,952		224		—		—		3,755		3,979
Recreational finance		7		202		202		—		—		—		202
Automobile		73		1,330		1,318		—		—		12		1,330
Total		557	$	175,583	$	90,639	$	978	$	10,896	$	77,711	$	180,224

					Post-modification (a)
Year Ended December 31, 2017	Number		Pre- modification Recorded Investment		Principal Deferral		Interest Rate Reduction		Other		Combination of Concession Types		Total
	(Dollars in thousands)

Commercial, financial, leasing, etc.		217	$	111,036	$	25,051	$	—	$	6,459	$	57,153	$	88,663
Real estate:
Commercial		83		44,924		17,039		—		868		22,975		40,882
Residential builder and developer		3		12,291		—		—		—		10,879		10,879
Other commercial construction		2		168		168		—		—		—		168
Residential		141		31,827		16,633		—		—		17,974		34,607
Residential — limited documentation		20		4,230		911		—		—		3,661		4,572
Consumer:
Home equity lines and loans		110		10,049		1,137		—		491		8,585		10,213
Recreational finance		9		160		160		—		—		—		160
Automobile		69		1,378		1,203		—		—		175		1,378
Total		654	$	216,063	$	62,302	$	—	$	7,818	$	121,402	$	191,522

(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.

Troubled debt restructurings are considered to be impaired loans and for purposes of establishing the allowance for credit losses are evaluated for impairment giving consideration to the impact of the modified loan terms on the present value of the loan’s expected cash flows. Impairment of troubled debt restructurings that have subsequently defaulted may also be measured based on the loan’s observable market price or the fair value of collateral if the loan is collateral-dependent. Charge-offs may also be recognized on troubled debt restructurings that have subsequently defaulted. Loans that were modified as troubled debt restructurings during the twelve months ended December 31, 2019, 2018 and 2017 and for which there was a subsequent payment default during the respective year were not material.

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 $28 million and $77 million at December 31, 2019 and 2018, respectively. During 2019, new borrowings by such persons amounted to $1 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 $50 million.

At December 31, 2019, approximately $11.9 billion of commercial loans and leases, $13.3 billion of commercial real estate loans, $11.5 billion of one-to-four family residential real estate loans, $2.3 billion of home equity loans and lines of credit and $7.5 billion of other consumer loans were pledged to secure outstanding borrowings from the FHLB of New York and available lines of credit as described in note 8.

The Company’s loan and lease portfolio includes commercial lease financing receivables consisting of direct financing and leveraged leases for machinery and equipment, railroad equipment, 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.

Effective January 1, 2019, the Company adopted new guidance related to lease accounting published by the Financial Accounting Standards Board (“FASB”). Under the new guidance, the accounting applied by lessors is largely unchanged from previous GAAP, however, the guidance eliminates the accounting model for leveraged leases that commence after the effective date of the guidance. A summary of lease financing receivables follows:

	December 31
	2019			2018
	(In thousands)
Commercial leases:
Direct financings:
Lease payments receivable	$	1,164,567		$	1,155,464
Estimated residual value of leased assets		84,540			85,169
Unearned income		(106,780	)		(110,458	)
Investment in direct financings		1,142,327			1,130,175
Leveraged leases:
Lease payments receivable		82,065			85,007
Estimated residual value of leased assets		81,025			81,261
Unearned income		(31,596	)		(33,717	)
Investment in leveraged leases		131,494			132,551
Total investment in leases	$	1,273,821		$	1,262,726
Deferred taxes payable arising from leveraged leases	$	70,245		$	74,995

Included within the estimated residual value of leased assets at December 31, 2019 and 2018 were $37 million and $39 million, respectively, in residual value associated with direct financing leases that are guaranteed by the lessees or others.

At December 31, 2019, the minimum future lease payments to be received from lease financings were as follows:

	(In thousands)
Year ending December 31:
2020	$	332,719
2021		297,875
2022		227,652
2023		161,296
2024		84,433
Later years		142,657
	$	1,246,632

The amount of foreclosed residential real estate property held by the Company was $76 million and $77 million at December 31, 2019 and 2018, respectively. There were $402 million and $391 million at December 31, 2019 and 2018, 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, 2019, approximately 36% were government guaranteed.

Allowance for credit losses

12 Months Ended

Dec. 31, 2019

Receivables [Abstract]

Allowance for credit losses

4. Allowance for credit losses

Changes in the allowance for credit losses for the years ended December 31, 2019, 2018 and 2017 were as follows:

	Commercial, Financial,			Real Estate
	Leasing, etc.			Commercial			Residential			Consumer			Unallocated			Total
	(In thousands)
2019
Beginning balance	$	330,055			341,655			69,125			200,564			78,045		$	1,019,444
Provision for credit losses		69,702			(10,726	)		(8,585	)		126,029			(420	)		176,000
Net charge-offs
Charge-offs		(58,244	)		(12,664	)		(12,711	)		(154,089	)		—			(237,708	)
Recoveries		24,581			3,936			8,204			56,614			—			93,335
Net charge-offs		(33,663	)		(8,728	)		(4,507	)		(97,475	)		—			(144,373	)
Ending balance	$	366,094			322,201			56,033			229,118			77,625		$	1,051,071

2018
Beginning balance	$	328,599			374,085			65,405			170,809			78,300		$	1,017,198
Provision for credit losses		33,967			(41,181	)		12,401			127,068			(255	)		132,000
Net charge-offs
Charge-offs		(60,414	)		(12,286	)		(15,345	)		(143,196	)		—			(231,241	)
Recoveries		27,903			21,037			6,664			45,883			—			101,487
Net (charge-offs) recoveries		(32,511	)		8,751			(8,681	)		(97,313	)		—			(129,754	)
Ending balance	$	330,055			341,655			69,125			200,564			78,045		$	1,019,444

2017
Beginning balance	$	330,833			362,719			61,127			156,288			78,030		$	988,997
Provision for credit losses		41,511			6,715			16,094			103,410			270			168,000
Net charge-offs
Charge-offs		(64,941	)		(7,931	)		(20,799	)		(130,927	)		—			(224,598	)
Recoveries		21,196			12,582			8,983			42,038			—			84,799
Net (charge-offs) recoveries		(43,745	)		4,651			(11,816	)		(88,889	)		—			(139,799	)
Ending balance	$	328,599			374,085			65,405			170,809			78,300		$	1,017,198

Despite the allocations 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 establishing the allowance for credit losses, the Company estimates losses attributable to specific troubled credits identified through both normal and targeted credit review processes and also estimates losses inherent in other loans and leases on a collective basis. For purposes of determining the level of the allowance for credit losses, the Company evaluates its loan and lease portfolio by loan type. The amounts of loss components in the Company’s loan and lease portfolios are determined through a loan-by-loan analysis of larger balance commercial loans and commercial real estate loans that are in nonaccrual status and by applying loss factors to groups of loan balances based on loan type and management’s classification of such loans under the Company’s loan grading system. Measurement of the specific loss components is typically based on expected future cash flows, collateral values and other factors that may impact the borrower’s ability to pay. In determining the allowance for credit losses, the Company utilizes a loan grading system that is applied to commercial and commercial real estate credits on an individual loan basis. Loan grades are assigned loss factors that reflect the Company’s loss estimate for each group of loans and leases. Factors considered in assigning loan grades and loss factors 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; levels of and trends in portfolio charge-offs and recoveries; levels of and trends in portfolio delinquencies and impaired loans; changes in the risk profile of specific portfolios; trends in volume and terms of loans; effects of changes in credit concentrations; and observed trends and practices in the banking industry.

The following tables provide information with respect to loans and leases that were considered impaired as of December 31, 2019 and 2018 and for the years ended December 31, 2019, 2018 and 2017.

	December 31, 2019						December 31, 2018
	Recorded Investment		Unpaid Principal Balance		Related Allowance		Recorded Investment		Unpaid Principal Balance		Related Allowance
	(In thousands)
With an allowance recorded:
Commercial, financial, leasing, etc.	$	230,444		257,745		74,435		153,478		175,549		46,034
Real estate:
Commercial		60,745		73,026		7,713		110,253		125,117		11,937
Residential builder and developer		9,559		9,856		121		5,981		6,557		462
Other commercial construction		12,425		24,908		1,354		10,563		11,113		640
Residential		125,623		145,497		6,873		124,974		147,817		5,402
Residential — limited documentation		64,268		77,359		2,300		74,156		90,066		3,000
Consumer:
Home equity lines and loans		46,325		51,238		8,957		47,982		53,248		9,135
Recreational finance		5,270		9,579		1,095		6,138		9,163		1,261
Automobile		3,256		3,344		703		3,527		3,599		729
Other		4,542		8,341		915		5,203		8,380		1,046
		562,457		660,893		104,466		542,255		630,609		79,646
With no related allowance recorded:
Commercial, financial, leasing, etc.		139,127		152,132		—		105,507		136,128		—
Real estate:
Commercial		117,751		131,406		—		113,376		124,657		—
Residential builder and developer		3,378		3,378		—		2,593		2,602		—
Other commercial construction		20,345		21,306		—		11,710		11,880		—
Residential		18,090		23,365		—		15,379		20,496		—
Residential — limited documentation		4,985		8,348		—		5,631		9,796		—
		303,676		339,935		—		254,196		305,559		—
Total:
Commercial, financial, leasing, etc.		369,571		409,877		74,435		258,985		311,677		46,034
Real estate:
Commercial		178,496		204,432		7,713		223,629		249,774		11,937
Residential builder and developer		12,937		13,234		121		8,574		9,159		462
Other commercial construction		32,770		46,214		1,354		22,273		22,993		640
Residential		143,713		168,862		6,873		140,353		168,313		5,402
Residential — limited documentation		69,253		85,707		2,300		79,787		99,862		3,000
Consumer:
Home equity lines and loans		46,325		51,238		8,957		47,982		53,248		9,135
Recreational finance		5,270		9,579		1,095		6,138		9,163		1,261
Automobile		3,256		3,344		703		3,527		3,599		729
Other		4,542		8,341		915		5,203		8,380		1,046
Total	$	866,133		1,000,828		104,466		796,451		936,168		79,646

	Year Ended December 31, 2019						Year Ended December 31, 2018
			Interest Income Recognized						Interest Income Recognized
	Average Recorded Investment		Total		Cash Basis		Average Recorded Investment		Total		Cash Basis
	(In thousands)

Commercial, financial, leasing, etc.	$	303,712		8,960		8,960		263,018		7,873		7,873
Real estate:
Commercial		208,200		5,850		5,850		194,451		10,880		10,880
Residential builder and developer		10,863		357		357		8,699		1,779		1,779
Other commercial construction		26,440		634		634		11,467		3,474		3,474
Residential		142,400		9,200		3,567		129,593		8,386		3,456
Residential — limited documentation		74,399		5,463		881		82,854		6,118		1,723
Consumer:
Home equity lines and loans		47,168		1,639		270		48,591		1,698		289
Recreational finance		5,707		558		17		1,849		333		9
Automobile		3,445		214		72		9,262		690		69
Other		5,025		525		11		4,413		230		13
Total	$	827,359		33,400		20,619		754,197		41,461		29,565

	Year Ended December 31, 2017
			Interest Income Recognized
	Average Recorded Investment		Total		Cash Basis
	(In thousands)

Commercial, financial, leasing, etc.	$	240,157		3,894		3,894
Real estate:
Commercial		207,616		4,497		4,497
Residential builder and developer		16,209		6,419		6,419
Other commercial construction		15,142		1,001		1,001
Residential		110,646		7,177		3,406
Residential — limited documentation		93,097		5,981		1,607
Consumer:
Home equity lines and loans		47,323		1,681		400
Recreational finance		1,041		212		9
Automobile		15,045		1,025		81
Other		2,322		96		2
Total	$	748,598		31,983		21,316

Commercial loans and commercial real estate 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. Furthermore, criticized nonaccrual commercial loans and commercial real estate loans are considered impaired and, as a result, specific loss allowances on such loans are established within the allowance for credit losses to the extent appropriate in each individual instance.

The following table summarizes the loan grades applied to the various classes of the Company’s commercial loans and commercial real estate loans.

			Real Estate
	Commercial,				Residential		Other
	Financial,				Builder and		Commercial
	Leasing, etc.		Commercial		Developer		Construction
	(In thousands)
December 31, 2019
Pass	$	22,595,821		25,728,725		1,419,162		7,092,799
Criticized accrual		895,790		770,609		124,101		211,292
Criticized nonaccrual		346,557		158,474		3,982		32,770
Total	$	23,838,168		26,657,808		1,547,245		7,336,861
December 31, 2018
Pass	$	21,693,705		24,539,706		1,546,002		6,890,562
Criticized accrual		1,049,848		866,987		139,509		150,115
Criticized nonaccrual		234,423		203,672		4,798		22,205
Total	$	22,977,976		25,610,365		1,690,309		7,062,882

In determining the allowance for credit losses, residential real estate loans and consumer loans are generally evaluated collectively after considering such factors as payment performance and recent loss experience and trends, which are mainly driven by current collateral values in the market place as well as the amount of loan defaults. Loss rates on such loans are determined by reference to recent charge-off history and are evaluated (and adjusted if deemed appropriate) through consideration of other factors including near-term forecasted loss estimates developed by the Company’s credit department. In arriving at such forecasts, the Company considers the current estimated fair value of its collateral based on geographical adjustments for home price depreciation/appreciation and overall borrower repayment performance. With regard to collateral values, the realizability of such values by the Company contemplates repayment of any first lien position prior to recovering amounts on a second lien position. However, residential real estate loans and outstanding balances of home equity loans and lines of credit that are more than 150 days past due are generally evaluated for collectibility on a loan-by-loan basis by giving consideration to estimated collateral values. The carrying value of residential real estate loans and home equity loans and lines of credit for which a partial charge-off has been recognized totaled $25 million and $19 million, respectively, at December 31, 2019 and $29 million and $23 million, respectively, at December 31, 2018. Residential real estate loans and home equity loans and lines of credit that were more than 150 days past due but did not require a partial charge-off because the net realizable value of the collateral exceeded the outstanding customer balance were $18 million and $29 million, respectively, at December 31, 2019 and $21 million and $31 million, respectively, at December 31, 2018.

The Company also measures additional losses for purchased impaired loans when it is probable that the Company will be unable to collect all cash flows expected at acquisition plus additional cash flows expected to be collected arising from changes in estimates after acquisition. The determination of the allocated portion of the allowance for credit losses is very subjective. Given that inherent subjectivity and potential imprecision involved in determining the allocated portion of the allowance for credit losses, the Company also provides an inherent unallocated portion of the allowance. The unallocated portion of the allowance is intended to recognize probable losses that are not otherwise identifiable and includes management’s subjective determination of amounts necessary to provide for the possible use of imprecise estimates in determining the allocated portion of the allowance. Therefore, the level of the unallocated portion of the allowance is primarily reflective of the inherent

imprecision in the various calculations used in determining the allocated portion of the allowance for credit losses. Other factors that could also lead to changes in the unallocated portion include the effects of expansion into new markets for which the Company does not have the same degree of familiarity and experience regarding portfolio performance in changing market conditions, the introduction of new loan and lease product types, and other risks associated with the Company’s loan portfolio that may not be specifically identifiable.

The allocation of the allowance for credit losses summarized on the basis of the Company’s impairment methodology was as follows:

	Commercial, Financial,		Real Estate
	Leasing, etc.		Commercial		Residential		Consumer		Total
	(In thousands)
December 31, 2019
Individually evaluated for impairment	$	74,435		9,188		9,173		11,670	$	104,466
Collectively evaluated for impairment		291,659		313,013		43,656		217,448		865,776
Purchased impaired		—		—		3,204		—		3,204
Allocated	$	366,094		322,201		56,033		229,118		973,446
Unallocated										77,625
Total									$	1,051,071
December 31, 2018
Individually evaluated for impairment	$	46,034		13,039		8,402		12,171	$	79,646
Collectively evaluated for impairment		284,021		328,616		48,326		188,393		849,356
Purchased impaired		—		—		12,397		—		12,397
Allocated	$	330,055		341,655		69,125		200,564		941,399
Unallocated										78,045
Total									$	1,019,444

The recorded investment in loans and leases summarized on the basis of the Company’s impairment methodology was as follows:

	Commercial, Financial,		Real Estate
	Leasing, etc.		Commercial		Residential		Consumer		Total
	(In thousands)
December 31, 2019
Individually evaluated for impairment	$	369,571		224,203		212,966		59,393	$	866,133
Collectively evaluated for impairment		23,468,597		35,300,120		15,733,174		15,327,300		89,829,191
Purchased impaired		—		17,591		209,954		—		227,545
Total	$	23,838,168		35,541,914		16,156,094		15,386,693	$	90,922,869
December 31, 2018
Individually evaluated for impairment	$	258,985		254,476		220,140		62,850	$	796,451
Collectively evaluated for impairment		22,718,991		34,098,670		16,641,411		13,907,649		87,366,721
Purchased impaired		—		10,410		292,895		—		303,305
Total	$	22,977,976		34,363,556		17,154,446		13,970,499	$	88,466,477

Premises and equipment

12 Months Ended

Dec. 31, 2019

Property Plant And Equipment [Abstract]

Premises and equipment

5. Premises and equipment

The detail of premises and equipment was as follows:

	December 31
	2019		2018
	(In thousands)
Land	$	96,118	$	97,082
Buildings		482,182		465,482
Leasehold improvements		262,438		240,731
Furniture and equipment — owned		739,724		669,782
Furniture and equipment — capital leases		14,232		18,582
		1,594,694		1,491,659
Less: accumulated depreciation and amortization
Owned assets		882,272		835,218
Capital leases		8,425		9,033
		890,697		844,251
Right of use assets — operating leases		436,927		—
Premises and equipment, net	$	1,140,924	$	647,408

The January 1, 2019 adoption of new lease accounting guidance from the FASB resulted in the Company recording right-of-use assets and lease liabilities in the consolidated balance sheet for all operating leases with a term greater than twelve months. In addition, the Company elected the practical expedients that (1) reassessment is not needed for whether any existing contracts are or contain leases, (2) reassessment of the classification of existing operating and finance leases is not required, and (3) a lease that has a term of twelve months or less is not required to apply the asset and liability recognition requirements.

The Company determines whether a contract contains a lease based on whether a contract, or a part of a contract, conveys the right to control the use of an identified asset for a period of time in exchange for consideration. If it is determined that a contract contains a lease, the consideration in the contract is separated between lease and nonlease components (for example, taxes or common area maintenance). In calculating the present value of the lease payments, the Company has utilized its incremental secured borrowing rate based on the lease term.

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, which prior to the adoption of the guidance were not reflected in the consolidated balance sheet.

As of December 31, 2019, the Company recognized $488 million of operating lease liabilities as a component of “accrued interest and other liabilities” in the consolidated balance sheet.

The Company’s noncancelable operating lease agreements expire at various dates over the next 22 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, 2019
	(Dollars in thousands)
Lease cost
Operating lease cost	$	100,669
Short-term lease cost		105
Variable lease cost		2,332
Total lease cost	$	103,106

Other information
Right-of-use assets obtained in exchange for new operating lease liabilities	$	132,219
Cash paid toward lease liabilities		101,869
Weighted-average remaining lease term	7 years
Weighted-average discount rate		3.01	%

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

	(In thousands)
Year ending December 31:
2020	$	100,447
2021		95,199
2022		79,794
2023		62,766
2024		50,539
Later years		154,585
Total lease payments		543,330
Less: imputed interest		55,775
Total	$	487,555

Net lease expense for all operating leases totaled $111 million in 2018 and $114 million in 2017. All other operating leasing activities were not material to the Company’s consolidated results of operations. Minimum lease payments required under capital leases are not material.

Capitalized servicing assets

12 Months Ended

Dec. 31, 2019

Transfers And Servicing [Abstract]

Capitalized servicing assets

6. Capitalized servicing assets

Changes in capitalized servicing assets were as follows:

	Residential Mortgage Loans									Commercial Mortgage Loans
For the Year Ended December 31,	2019			2018			2017			2019			2018			2017
	(In thousands)
Beginning balance	$	120,509		$	114,978		$	117,351		$	114,663		$	114,076		$	103,764
Originations		26,067			28,985			28,792			41,370			26,298			34,620
Purchases		144,326			454			699			—			—			—
Amortization		(46,491	)		(23,908	)		(31,864	)		(25,397	)		(25,711	)		(24,308	)
		244,411			120,509			114,978			130,636			114,663			114,076
Valuation allowance		(7,000	)		—			—			—			—			—
Ending balance, net	$	237,411		$	120,509		$	114,978		$	130,636		$	114,663		$	114,076

Residential mortgage loans serviced for others were $32.3 billion at December 31, 2019, $22.2 billion at December 31, 2018 and $22.6 billion at December 31, 2017. Excluded from residential mortgage loans serviced for others were loans sub-serviced for others of $62.8 billion, $56.8 billion and $56.6 billion at December 31, 2019, 2018, and 2017, respectively. On January 31, 2019, the Company purchased servicing rights for residential real estate loans that had outstanding principal balances at that date of approximately $13.3 billion. The purchase price of such servicing rights was approximately $144 million. Commercial mortgage loans serviced for others were $17.6 billion at December 31, 2019, $15.5 billion at December 31, 2018 and $13.6 billion at December 31, 2017. Excluded from commercial mortgage loans serviced for others were loans sub-serviced for others of $3.4 billion at December 31, 2019, $2.7 billion at December 31, 2018 and $2.6 billion at December 31, 2017.

The estimated fair value of capitalized residential mortgage loan servicing assets was approximately $297 million at December 31, 2019 and $240 million at December 31, 2018. The fair value of capitalized residential mortgage loan servicing assets was estimated using weighted-average discount rates of 10.6% and 11.4% at December 31, 2019 and 2018, respectively, and contemporaneous prepayment assumptions that vary by loan type. At December 31, 2019 and 2018, the discount rate represented a weighted-average option-adjusted spread (“OAS”) of 928 basis points (hundredths of one percent) and 963 basis points, respectively, over market implied forward London Interbank Offered Rates (“LIBOR”). 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 $153 million and $135 million at December 31, 2019 and 2018, respectively. An 18% discount rate was used to estimate the fair value of capitalized commercial mortgage loan servicing rights at December 31, 2019 and 2018 with no prepayment assumptions because, 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 loan. 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 on prepayments or changes in interest rates.

The key economic assumptions used to determine the fair value of significant portfolios of capitalized servicing rights at December 31, 2019 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.

	Residential			Commercial
	(Dollars in thousands)

Weighted-average prepayment speeds		15.84	%
Impact on fair value of 10% adverse change	$	(16,555	)
Impact on fair value of 20% adverse change		(31,475	)
Weighted-average OAS		9.28	%
Impact on fair value of 10% adverse change	$	(8,070	)
Impact on fair value of 20% adverse change		(15,663	)
Weighted-average discount rate					18.00	%
Impact on fair value of 10% adverse change				$	(6,948	)
Impact on fair value of 20% adverse change					(13,395	)

Goodwill and other intangible assets

12 Months Ended

Dec. 31, 2019

Goodwill And Intangible Assets Disclosure [Abstract]

Goodwill and other intangible assets

7. 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. At December 31, 2019 the Company reduced by $933 million the gross carrying amount and accumulated amortization associated with intangible assets that had been fully amortized and, therefore, had no remaining net carrying amount. Total amortizing intangible assets were comprised of the following:

	Gross Carrying Amount		Accumulated Amortization		Net Carrying Amount
	(In thousands)
December 31, 2019
Core deposit	$	131,664	$	105,802	$	25,862
Other		6,757		3,585		3,172
Total	$	138,421	$	109,387	$	29,034
December 31, 2018
Core deposit	$	887,459	$	843,572	$	43,887
Other		182,568		179,388		3,180
Total	$	1,070,027	$	1,022,960	$	47,067

Amortization of core deposit and other intangible assets was generally computed using accelerated methods over original amortization periods of three to ten years. The weighted-average original amortization period was approximately eight years. Amortization expense for core deposit and other intangible assets was $19 million, $25 million and $31 million for the years ended December 31, 2019, 2018 and 2017, respectively. Estimated amortization expense in future years for such intangible assets is as follows:

	(In thousands)
Year ending December 31:
2020	$	14,869
2021		10,167
2022		3,998
	$	29,034

The Company completed annual goodwill impairment tests as of October 1, 2019, 2018 and 2017. 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. To test for goodwill impairment at each 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 dates 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 tests, the Company concluded that the amount of recorded goodwill was not impaired at the respective testing dates.

A summary of goodwill assigned to each of the Company’s reportable segments as of December 31, 2019 and 2018 for purposes of testing for impairment is as follows:

	(In thousands)

Business Banking	$	864,366
Commercial Banking		1,401,873
Commercial Real Estate		654,389
Discretionary Portfolio		—
Residential Mortgage Banking		—
Retail Banking		1,309,191
All Other		363,293
Total	$	4,593,112

Borrowings

12 Months Ended

Dec. 31, 2019

Debt Disclosure [Abstract]

Borrowings

8. Borrowings

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

	Federal Funds Purchased and Repurchase Agreements			Other Short-term Borrowings			Total
	(Dollars in thousands)
At December 31, 2019
Amount outstanding	$	62,363		$	—		$	62,363
Weighted-average interest rate		0.14	%		—			0.14	%
For the year ended December 31, 2019
Highest amount at a month-end	$	3,402,566		$	5,000,000
Daily-average amount outstanding		260,322			799,068		$	1,059,390
Weighted-average interest rate		1.86	%		2.49	%		2.34	%
At December 31, 2018
Amount outstanding	$	198,378		$	4,200,000		$	4,398,378
Weighted-average interest rate		1.68	%		2.63	%		2.58	%
For the year ended December 31, 2018
Highest amount at a month-end	$	2,654,416		$	4,200,000
Daily-average amount outstanding		261,200			69,465		$	330,665
Weighted-average interest rate		1.49	%		2.16	%		1.63	%
At December 31, 2017
Amount outstanding	$	175,099		$	—		$	175,099
Weighted-average interest rate		0.92	%		—			0.92	%
For the year ended December 31, 2017
Highest amount at a month-end	$	204,977		$	1,500,000
Daily-average amount outstanding		188,459			16,164		$	204,623
Weighted-average interest rate		0.69	%		1.27	%		0.74	%

Short-term borrowings have a stated maturity of one year or less at the date the Company enters into the obligation. In general, short-term repurchase agreements outstanding at December 31, 2019 matured on the next business day following year-end.

At December 31, 2019, M&T Bank had lines of credit under formal agreements as follows:

	(In thousands)

Outstanding borrowings	$	1,869
Unused		32,578,083

At December 31, 2019, M&T Bank had borrowing facilities available with the FHLBs whereby M&T Bank could borrow up to approximately $18.2 billion. Additionally, M&T Bank had an available line of credit with the Federal Reserve Bank of New York totaling approximately

$14.4 billion at December 31, 2019. 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,
	2019		2018
	(In thousands)
Senior notes of M&T:
Variable rate due 2023	$	249,756	$	249,688
3.55% due 2023		520,454		506,021
Senior notes of M&T Bank:
Variable rate due 2021		349,893		349,794
Variable rate due 2022		249,758		249,658
2.25% due 2019		—		645,801
2.05% due 2020		749,254		737,793
2.10% due 2020		749,864		741,965
2.625% due 2021		654,136		646,301
2.50% due 2022		652,714		634,525
2.90% due 2025		749,572		749,488
Advances from FHLB:
Fixed rates		1,815		576,446
Agreements to repurchase securities		101,679		409,154
Subordinated notes of M&T Bank:
Variable rate due 2020		409,361		409,361
Variable rate due 2021		500,000		500,000
3.40% due 2027		514,353		481,692
Junior subordinated debentures of M&T associated with preferred capital securities:
Fixed rates:
BSB Capital Trust I — 8.125%, due 2028		15,728		15,705
Provident Trust I — 8.29%, due 2028		28,235		27,489
Southern Financial Statutory Trust I — 10.60%, due 2030		6,770		6,713
Variable rates:
First Maryland Capital I — due 2027		147,871		147,333
First Maryland Capital II — due 2027		149,943		149,280
Allfirst Asset Trust — due 2029		96,930		96,785
BSB Capital Trust III — due 2033		15,464		15,464
Provident Statutory Trust III — due 2033		55,867		55,143
Southern Financial Capital Trust III — due 2033		8,236		8,141
Other		8,533		35,174
	$	6,986,186	$	8,444,914

The senior notes of M&T were issued in July 2018. The variable rate notes pay interest quarterly at a rate that is indexed to the three-month LIBOR. The contractual interest rates for those notes were 2.62% at December 31, 2019 and 2.51% at December 31, 2018.

The variable rate senior notes of M&T Bank pay interest quarterly at rates that are indexed to the three-month LIBOR. The contractual interest rates for those notes ranged from 2.21% to 2.54% at December 31, 2019 and 2.76% to 3.25% at December 31, 2018. The weighted-average contractual interest rate was 2.34% at December 31, 2019 and 2.96% at December 31, 2018.

Long-term fixed rate advances from the FHLB had weighted-average contractual interest rates of 5.82% at December 31, 2019 and 2.06% at December 31, 2018. Advances from the FHLB outstanding at December 31, 2019 mature in 2029 and 2035 and are secured by residential real estate loans, commercial real estate loans and investment securities.

The remaining long-term agreement to repurchase securities at December 31, 2019 had a contractual interest rate of 4.29%. Agreements to repurchase securities outstanding at December 31, 2018 had contractual interest rates that ranged from 4.09% to 4.58%. The outstanding agreement at December 31, 2019 has a repurchase date in 2020, however, the contractual maturities of the underlying investment securities extend beyond such repurchase date. The agreement is subject to legally enforceable master netting arrangements, however, the Company has not offset any amounts related to the agreement in its consolidated financial statements. The Company posted collateral consisting primarily of government guaranteed mortgage-backed securities of $108 million and $428 million at December 31, 2019 and 2018, respectively.

The subordinated notes of M&T Bank are unsecured and are subordinate to the claims of its other creditors. The notes that mature in 2020 pay interest monthly at a rate that is indexed to the one-month LIBOR. The contractual interest rate was 3.02% and 3.72% at December 31, 2019 and 2018, respectively. The notes that mature in 2021 pay interest quarterly at a rate that is indexed to the three-month LIBOR. The contractual interest rate was 2.55% at December 31, 2019 and 3.38% at December 31, 2018.

The fixed and variable rate junior subordinated deferrable interest debentures of M&T (“Junior Subordinated Debentures”) are held by various trusts and were issued in connection with the issuance by those trusts of preferred capital securities (“Capital Securities”) and common securities (“Common Securities”). The proceeds from the issuances of the 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 Capital Securities represent preferred undivided interests in the assets of the corresponding trust. Under the Federal Reserve Board’s risk-based capital guidelines, the 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 LIBOR. Those rates ranged from 2.76% to 5.34% at December 31, 2019 and from 3.39% to 5.69% at December 31, 2018. The weighted-average variable rates payable on those Junior Subordinated Debentures were 3.37% at December 31, 2019 and 3.94% at December 31, 2018.

Holders of the 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 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 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 Capital Securities. The obligations under such guarantee and the Capital Securities are subordinate and junior in right of payment to all senior indebtedness of M&T.

The 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 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 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.

Long-term borrowings at December 31, 2019 mature as follows:

	(In thousands)
Year ending December 31:
2020	$	2,010,251
2021		1,506,667
2022		907,794
2023		770,211
2024		479
Later years		1,790,784
	$	6,986,186

Shareholders' equity

12 Months Ended

Dec. 31, 2019

Equity [Abstract]

Shareholders' equity

9. Shareholders’ equity

M&T is authorized to issue 1,000,000 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 as of December 31, 2019 and 2018 is presented below:

	December 31, 2019				December 31, 2018
	Shares Issued and Outstanding		Carrying Value		Shares Issued and Outstanding		Carrying Value
	(Dollars in thousands)
Series A (a)
Fixed Rate Cumulative Perpetual Preferred Stock, $1,000 liquidation preference per share		—		—		230,000	$	230,000
Series C (a)
Fixed Rate Cumulative Perpetual Preferred Stock, $1,000 liquidation preference per share		—		—		151,500	$	151,500
Series E (b)
Fixed-to-Floating Rate Non-cumulative Perpetual Preferred Stock, $1,000 liquidation preference per share		350,000	$	350,000		350,000	$	350,000
Series F (c)
Fixed-to-Floating Rate Non-cumulative Perpetual Preferred Stock, $10,000 liquidation preference per share		50,000	$	500,000		50,000	$	500,000
Series G (d)
Fixed-Rate Reset Non-cumulative Perpetual Preferred Stock, $10,000 liquidation preference per share		40,000	$	400,000		—		—

(a)	The shares were fully redeemed in August 2019, having received the approval of the Federal Reserve to redeem such shares after issuing the Series G preferred stock. Declared dividends per share were $47.8125 in 2019 and $63.75 in each of 2018 and 2017.

(b)

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 LIBOR plus 361 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 2019, 2018 and 2017.

(c)

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 LIBOR plus 352 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 2019, 2018 and 2017.

(d)

Dividends, if declared, are paid semi-annually at a rate of 5.0% through July 31, 2024 and thereafter will be paid semiannually 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 $125.694 in 2019.

Revenue from contracts with customers

12 Months Ended

Dec. 31, 2019

Revenue From Contract With Customer [Abstract]

Revenue from contracts with customers

10. Revenue from contracts with customers

Effective January 1, 2018 the Company adopted amended accounting and disclosure guidance for revenue from contracts with customers under the modified retrospective approach. 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 foreign exchange 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 the amended guidance for revenue from contracts with customers. As a result of the adoption, the Company began reporting credit card interchange revenue net of $25 million and $14 million of rewards in other revenues from operations for the years ended December 31, 2019 and 2018, respectively. Credit card rewards expense of $13 million for the year ended December 31, 2017 was included in other costs of operations. The adjustment to beginning retained earnings as well as the impact of any changes in timing of revenue recognition of noninterest income items within the scope of the guidance was not material to the Company’s consolidated financial position at December 31, 2017 or its consolidated results of operations for the year ended December 31, 2018.

For noninterest income revenue streams, the Company 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.

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, 2019 and 2018, the Company had $62 million and $56 million, respectively, of uncollected 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 Company’s 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 each of December 31, 2019 and 2018, the Company had deferred revenue of $43 million related to the sources in the accompanying tables and recorded such amounts in accrued interest and other liabilities on its consolidated balance sheet. The following tables summarize sources of the Company’s noninterest income during 2019 and 2018 that are subject to the amended guidance.

	Business Banking		Commercial Banking		Commercial Real Estate		Discretionary Portfolio		Residential Mortgage Banking		Retail Banking		All Other		Total
Year Ended December 31, 2019	(In thousands)

Classification in consolidated statement of income
Service charges on deposit accounts	$	60,690		93,044		9,828		—		4		263,659		5,753	$	432,978
Trust income		31		963		—		—		—		—		571,614		572,608
Brokerage services income		—		—		—		—		—		—		48,922		48,922
Other revenues from operations:
Merchant discount and credit card fees		36,844		52,161		2,516		—		—		12,140		3,381		107,042
Other		—		7,498		8,615		1,776		3,492		36,144		34,088		91,613
	$	97,565		153,666		20,959		1,776		3,496		311,943		663,758	$	1,253,163
Year Ended December 31, 2018

Classification in consolidated statement of income
Service charges on deposit accounts	$	62,323		96,407		9,870		—		10		254,590		6,137	$	429,337
Trust income		9		917		—		—		—		—		536,659		537,585
Brokerage services income		—		—		—		—		—		—		51,069		51,069
Other revenues from operations:
Merchant discount and credit card fees		34,557		52,051		2,213		—		—		14,924		2,208		105,953
Other		—		8,796		7,259		1,738		3,814		38,529		30,233		90,369
	$	96,889		158,171		19,342		1,738		3,824		308,043		626,306	$	1,214,313

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 fees related to the Institutional Client Services (“ICS”) business and the Wealth Advisory Services (“WAS”) business. Revenues from the ICS business are largely derived from a variety of trustee, agency, investment, cash management and administrative services, whereas revenues from the WAS business are mainly derived from asset management, fiduciary services, and family office services. Trust fees may be billed in arrears or in advance and are recognized as revenues 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 fees such as interchange fees and merchant discount fees that are generally recognized when the cardholder’s transaction is approved and settled. Beginning in 2018, credit card rewards accrued to cardholders are recognized as a reduction of interchange revenue. Also included in other revenues from operations are insurance commissions, ATM surcharge fees, and advisory 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 fees are generally recognized at the conclusion of the advisory engagement when the Company has satisfied its service obligation.

Stock-based compensation plans

12 Months Ended

Dec. 31, 2019

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock-based compensation plans

11. Stock-based compensation plans

Stock-based compensation expense was $76 million in 2019, $66 million in 2018 and $61 million in 2017. The Company recognized income tax benefits related to stock-based compensation of $19 million in 2019, $24 million in 2018 and $35 million in 2017.

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, 2019 and 2018, respectively, there were 3,742,478 and 2,833,428 shares available for future grant under the Company’s equity incentive compensation plan.

Stock awards

Stock awards are comprised of restricted stock and restricted stock units. Stock awards granted since 2014 generally vest over three years. Stock awards granted prior to 2014 vested over four years. A portion of stock awards granted after 2013 require a performance condition to be met before such awards vest. The Company may issue shares from treasury stock to the extent available or issue new shares. The number of restricted shares issued was 181,939 in 2017 with a weighted-average grant date fair value of $30 million. There were no restricted shares issued in 2019 or 2018. The number of restricted stock units issued was 448,487 in 2019, 348,512 in 2018 and 235,983 in 2017, with a weighted-average grant date fair value of $74 million, $66 million and $38 million, respectively. Unrecognized compensation expense associated with restricted stock units was $22 million as of December 31, 2019 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, 2019		556,875		$	170.07		179,439		$	144.18
Granted		448,487			164.63		—			—
Vested		(298,243	)		157.90		(113,894	)		133.69
Cancelled		(15,892	)		173.48		(1,954	)		161.42
Unvested at December 31, 2019		691,227		$	171.72		63,591		$	162.45

Stock option awards

Stock options issued generally vest over three years and are exercisable over terms not exceeding ten years and one day. The Company used an option pricing model to estimate the grant date present value of stock options granted. The Company granted 164,244 and 116,852 stock options in 2019 and 2018, respectively. Stock options granted in 2017 were not significant. The fair value of options granted in each of 2019, 2018 and 2017 was not material.

A summary of stock option activity follows:

				Weighted-Average
	Stock Options Outstanding			Exercise Price		Life (In Years)		Aggregate Intrinsic Value (In thousands)

Outstanding at January 1, 2019		220,591		$	157.98
Granted		164,244			164.54
Exercised		(76,181	)		122.55
Expired		(3,202	)		176.41
Outstanding at December 31, 2019		305,452		$	170.15		8.0	$	2,301
Exercisable at December 31, 2019		66,076		$	159.96		5.1	$	1,454

For 2019, 2018 and 2017, M&T received $9 million, $60 million and $72 million, respectively, in cash and realized tax benefits from the exercise of stock options of $1 million, $3 million and $10 million, respectively. The intrinsic value of stock options exercised during those periods was $3 million, $16 million and $31 million, respectively. As of December 31, 2019, 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 2019, 2018 and 2017 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 71,676 in 2019, 58,167 in 2018 and 66,504 in 2017. As of December 31, 2019, there were 2,310,751 shares available for issuance under the plan. M&T received cash for shares purchased through the employee stock purchase plan of $11 million in 2019 and $10 million in each of 2018 and 2017. Compensation expense recognized for the stock purchase plan was not significant in 2019, 2018 or 2017.

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. 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 16,491 and 18,292 at December 31, 2019 and 2018, respectively. The obligation to issue shares is included in “common stock issuable” in the consolidated balance sheet.

Directors’ stock plan

The Company maintains a compensation plan for non-employee members of the Company’s boards of directors and directors advisory councils that allows such members to receive all or a portion of their compensation in shares of M&T common stock. Through December 31, 2019, 282,532 shares had been issued in connection with the directors’ stock plan.

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 5,043 and 6,271 at December 31, 2019 and 2018, respectively. The obligation to issue shares is included in “common stock issuable” in the consolidated balance sheet.

Pension plans and other postretirement benefits

12 Months Ended

Dec. 31, 2019

Compensation And Retirement Disclosure [Abstract]

Pension plans and other postretirement benefits

12. Pension plans and other postretirement benefits

The Company provides defined benefit 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
	2019			2018			2017
	(In thousands)

Service cost	$	17,294		$	20,346		$	20,193
Interest cost on benefit obligation		81,579			74,704			79,270
Expected return on plan assets		(122,139	)		(123,127	)		(108,524	)
Amortization of prior service cost		557			557			557
Recognized net actuarial loss		21,992			43,793			29,263
Net periodic pension cost (benefit)	$	(717	)	$	16,273		$	20,759

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

	Year Ended December 31
	2019			2018			2017
	(In thousands)

Service cost	$	859		$	938		$	1,172
Interest cost on benefit obligation		2,344			2,293			3,716
Amortization of prior service credit		(4,730	)		(4,729	)		(1,359	)
Recognized net actuarial gain		(1,247	)		(826	)		(988	)
Net other postretirement benefits cost (benefit)	$	(2,774	)	$	(2,324	)	$	2,541

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

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

	Pension Benefits						Other Postretirement Benefits
	2019			2018			2019			2018
	(In thousands)
Change in benefit obligation:
Benefit obligation at beginning of year	$	1,949,613		$	2,188,736		$	59,991		$	68,637
Service cost		17,294			20,346			859			938
Interest cost		81,579			74,704			2,344			2,293
Plan participants’ contributions		—			—			2,749			2,974
Actuarial (gain) loss		298,713			(228,897	)		(687	)		(4,758	)
Medicare Part D reimbursement		—			—			370			508
Benefits paid		(99,870	)		(105,276	)		(9,134	)		(10,601	)
Benefit obligation at end of year		2,247,329			1,949,613			56,492			59,991
Change in plan assets:
Fair value of plan assets at beginning of year		1,833,833			2,014,891			—			—
Actual return on plan assets		293,546			(90,657	)		—			—
Employer contributions		10,431			14,875			6,015			7,119
Plan participants’ contributions		—			—			2,749			2,974
Medicare Part D reimbursement		—			—			370			508
Benefits paid		(99,870	)		(105,276	)		(9,134	)		(10,601	)
Fair value of plan assets at end of year		2,037,940			1,833,833			—			—
Funded status	$	(209,389	)	$	(115,780	)	$	(56,492	)	$	(59,991	)
Accrued liabilities recognized in the consolidated balance sheet	$	(209,389	)	$	(115,780	)	$	(56,492	)	$	(59,991	)
Amounts recognized in accumulated other comprehensive income (“AOCI”) were:
Net loss (gain)	$	507,029		$	401,716		$	(17,308	)	$	(17,868	)
Net prior service cost (credit)		1,834			2,391			(27,007	)		(31,737	)
Pre-tax adjustment to AOCI		508,863			404,107			(44,315	)		(49,605	)
Taxes		(133,779	)		(106,240	)		11,650			13,041
Net adjustment to AOCI	$	375,084		$	297,867		$	(32,665	)	$	(36,564	)

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 $154 million as of December 31, 2019 and $143 million as of December 31, 2018.

The accumulated benefit obligation for all defined benefit pension plans was $2.2 billion and $1.9 billion at December 31, 2019 and 2018, respectively.

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 fair value of the plan assets. As indicated in the preceding table, as of December 31, 2019 the Company recorded a minimum liability adjustment of $465 million ($509 million related to pension plans and $(44) million related to other postretirement benefits) with a corresponding reduction of shareholders’ equity, net of applicable deferred taxes, of $342 million. In aggregate, the benefit plans realized a net loss during 2019 that resulted in an increase to the minimum liability adjustment from that which was recorded at December 31, 2018 of $110 million. The net loss in 2019 was mainly the result of lowering the discount rate used to measure the benefit obligation of all plans to 3.25% at December 31, 2019 from 4.25% used at the prior year-end, offset, in part, by the amortization of actuarial losses and a return on plan assets that exceeded 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.

	Pension Plans			Other Postretirement Benefit Plans			Total
	(In thousands)
2019
Net loss (gain)	$	127,305		$	(687	)	$	126,618
Amortization of prior service (cost) credit		(557	)		4,730			4,173
Amortization of actuarial (loss) gain		(21,992	)		1,247			(20,745	)
Total recognized in other comprehensive income, pre-tax	$	104,756		$	5,290		$	110,046
2018
Net gain	$	(15,113	)	$	(4,758	)	$	(19,871	)
Amortization of prior service (cost) credit		(557	)		4,729			4,172
Amortization of actuarial (loss) gain		(43,793	)		826			(42,967	)
Total recognized in other comprehensive income, pre-tax	$	(59,463	)	$	797		$	(58,666	)

The following table reflects the amortization of amounts in accumulated other comprehensive income expected to be recognized as components of net periodic benefit expense during 2020:

	Pension Plans		Other Postretirement Benefit Plans
	(In thousands)

Amortization of net prior service cost (credit)	$	557	$	(4,738	)
Amortization of net loss (gain)		55,851		(1,223	)

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. Participants do not contribute to the defined contribution pension plan. Pension expense recorded in 2019, 2018 and 2017 associated with the defined contribution pension plan was approximately $32 million, $29 million and $30 million, respectively.

Assumptions

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

	Pension Benefits						Other Postretirement Benefits
	2019			2018			2019			2018

Discount rate		3.25	%		4.25	%		3.25	%		4.25	%
Rate of increase in future compensation levels		4.29	%		4.31	%		—			—

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

	Pension Benefits									Other Postretirement Benefits
	2019			2018			2017			2019			2018			2017

Discount rate		4.25	%		3.50	%		4.00	%		4.25	%		3.50	%		4.00	%
Long-term rate of return on plan assets		6.50	%		6.50	%		6.50	%		—			—			—
Rate of increase in future compensation levels		4.31	%		4.33	%		4.39	%		—			—			—

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 pension expense 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 a decrease in pension expense of approximately $5 million; and the discount rate would have resulted in a decrease in pension expense of approximately $8 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

$75 million and a decrease of 25 basis points in the discount rate would have increased the benefit obligation by $79 million at December 31, 2019.

For measurement of other postretirement benefits, a 6.25% annual rate of increase in the per capita cost of covered health care benefits was assumed for 2020. The rate was assumed to decrease to 5.00% over nine years. A one-percentage point change in assumed health care cost trend rates would have had the following effects:

	+1%			-1%
	(In thousands)
Increase (decrease) in:
Service and interest cost	$	49	$	(45	)
Accumulated postretirement benefit obligation		834		(747	)

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 $439 million (22% of total assets) of real estate funds, private investments, hedge funds and other investments at December 31, 2019. 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, 2019 and 2018, by asset category, were as follows:

	Fair Value Measurement of Plan Assets At December 31, 2019
	Total		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
	(In thousands)
Asset category:
Money-market investments	$	38,461	$	33,870	$	4,591	$	—
Equity securities:
M&T		148,603		148,603		—		—
Domestic(a)		219,663		219,663		—		—
International(b)		10,476		10,476		—		—
Mutual funds:
Domestic(a)		238,872		238,872		—		—
International(b)		381,433		381,433		—		—
		999,047		999,047		—		—
Debt securities:
Corporate(c)		112,783		—		112,783		—
Government		190,679		—		190,679		—
International		6,648		—		6,648		—
Mutual funds:
Domestic(d)		249,075		249,075		—		—
		559,185		249,075		310,110		—
Other:
Diversified mutual fund		86,980		86,980		—		—
Real estate partnerships		21,905		3,939		—		17,966
Private equity / debt		87,966		—		—		87,966
Hedge funds		231,807		116,029		—		115,778
Guaranteed deposit fund		10,527		—		—		10,527
		439,185		206,948		—		232,237
Total(e)	$	2,035,878	$	1,488,940	$	314,701	$	232,237

	Fair Value Measurement of Plan Assets At December 31, 2018
	Total		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
	(In thousands)
Asset category:
Money-market investments	$	23,049	$	10,794	$	12,255	$	—
Equity securities:
M&T		125,299		125,299		—		—
Domestic(a)		191,640		191,640		—		—
International(b)		7,752		7,752		—		—
Mutual funds:
Domestic(a)		216,523		216,523		—		—
International(b)		316,923		316,923		—		—
		858,137		858,137		—		—
Debt securities:
Corporate(c)		103,672		—		103,672		—
Government		182,034		—		182,034		—
International		2,140		—		2,140		—
Mutual funds:
Domestic(d)		280,902		280,902		—		—
International		20,661		20,661		—		—
		589,409		301,563		287,846		—
Other:
Diversified mutual fund		74,446		74,446		—		—
Real estate partnerships		11,807		2,791		—		9,016
Private equity / debt		63,699		—		—		63,699
Hedge funds		200,811		125,309		—		75,502
Guaranteed deposit fund		10,415		—		—		10,415
		361,178		202,546		—		158,632
Total(e)	$	1,831,773	$	1,373,040	$	300,101	$	158,632

(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 80% of the mutual funds were invested in investment grade bonds and 20% in high-yielding bonds at December 31, 2019. Approximately 77% of the mutual funds were invested in investment grade bonds and 23% in high-yielding bonds at December 31, 2018. The holdings within the funds were spread across diverse industries.

(e)	Excludes dividends and interest receivable totaling $2 million at each of December 31, 2019 and 2018.

Pension plan assets included common stock of M&T with a fair value of $149 million (7% of total plan assets) at December 31, 2019 and $125 million (7% of total plan assets) at December 31, 2018. No investment in securities of a non-U.S. Government or government agency issuer exceeded ten percent of plan assets at December 31, 2019.

The changes in Level 3 pension plan assets measured at estimated fair value on a recurring basis during the year ended December 31, 2019 were as follows:

	Balance – January 1, 2019		Purchases (Sales)		Total Realized/ Unrealized Gains (Losses)		Balance – December 31, 2019
	(In thousands)
Other
Real estate partnerships	$	9,016	$	7,623	$	1,327	$	17,966
Private equity/debt		63,699		9,531		14,736		87,966
Hedge funds		75,502		27,000		13,276		115,778
Guaranteed deposit fund		10,415		—		112		10,527
Total	$	158,632	$	44,154	$	29,451	$	232,237

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 made voluntary contributions of $200 million to the qualified defined benefit pension plan in 2017. The Company did not make any contributions to the plan in 2019 or 2018. The Company is not required to make contributions to the qualified defined benefit plan in 2020, however, subject to the impact of actual events and circumstances that may occur in 2020, 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 $10 million and $15 million in 2019 and 2018, respectively. Payments made by the Company for postretirement benefits were $6 million and $7 million in 2019 and 2018, respectively. Payments for supplemental pension and other postretirement benefits for 2020 are not expected to differ from those made in 2019 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:

	Pension Benefits		Other Postretirement Benefits
	(In thousands)
Year ending December 31:
2020	$	100,800	$	6,622
2021		104,385		4,036
2022		107,368		3,972
2023		111,990		3,904
2024		115,962		3,829
2025 through 2029		619,663		17,919

The Company has a retirement savings plan (“RSP”) 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 Company makes an employer matching contribution in an amount equal to 75% of an employee’s contribution, up to 4.5% of the employee’s qualified compensation. 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 RSP totaled $48 million, $43 million and $38 million in 2019, 2018 and 2017, respectively.

Income taxes

12 Months Ended

Dec. 31, 2019

Income Tax Disclosure [Abstract]

Income taxes

13. Income taxes

The components of income tax expense were as follows:

	Year Ended December 31
	2019		2018			2017
	(In thousands)
Current
Federal	$	359,668	$	408,428		$	363,043
State and local		132,696		113,706			94,714
Total current		492,364		522,134			457,757
Deferred
Federal		40,769		(12,780	)		367,308
State and local		16,779		28,637			33,482
Total deferred		57,548		15,857			400,790
Amortization of investments in qualified affordable housing projects		68,200		52,169			57,009
Total income taxes applicable to pre-tax income	$	618,112	$	590,160		$	915,556

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, 2019, 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.

Income taxes attributable to gains or losses on bank investment securities were an expense of $5 million in 2019 and $7 million in 2017, and a benefit of $2 million in 2018. No alternative minimum tax expense was recognized in 2017.

The Tax Cuts and Jobs Act (“Tax Act”) was signed into law on December 22, 2017, reducing the corporate federal income tax rate from 35% to 21% effective January 1, 2018 and making other changes to U.S. corporate income tax laws, including eliminating the alternative minimum tax as of January 1, 2018. GAAP requires that the impact of the provisions of the Tax Act be accounted for in the period of enactment. Accordingly, the incremental income tax expense recorded by the Company in the fourth quarter of 2017 related to the Tax Act was $85 million. That additional expense was largely attributable to the reduction in carrying value of net deferred tax assets reflecting lower future tax benefits resulting from the lower corporate income tax rate. During 2018 the Company received approval from the Internal Revenue Service to change the timing of recognition of certain loan fees

retroactive to 2017. Given the reduction of the federal income tax rate, the change resulted in a $15 million reduction of income tax expense in 2018.

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
	2019			2018			2017
	(In thousands)

Income taxes at statutory federal income tax rate	$	534,925		$	526,730		$	813,352
Increase (decrease) in taxes:
Tax-exempt income		(27,319	)		(26,186	)		(40,778	)
State and local income taxes, net of federal income tax effect		118,085			112,451			83,327
Qualified affordable housing project federal tax credits, net		(15,324	)		(12,240	)		(16,015	)
Initial impact of enactment of Tax Act		—			—			85,431
Other		7,745			(10,595	)		(9,761	)
	$	618,112		$	590,160		$	915,556

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

	2019			2018			2017
	(In thousands)

Losses on loans and other assets	$	309,523		$	322,818		$	345,609
Operating lease liabilities		128,178			—			—
Retirement benefits		55,048			30,057			45,322
Postretirement and other employee benefits		24,023			23,563			26,009
Incentive and other compensation plans		26,861			24,796			25,050
Interest on loans		—			—			37,900
Stock-based compensation		27,912			26,759			26,676
Unrealized losses		—			52,580			—
Losses on cash flow hedges		—			1,861			4,033
Other		69,863			43,880			66,247
Gross deferred tax assets		641,408			526,314			576,846
Right of use assets and other leasing transactions		(326,626	)		(186,787	)		(181,159	)
Unrealized gains		(13,322	)		—			(94,285	)
Capitalized servicing rights		(56,649	)		(54,894	)		(51,781	)
Depreciation and amortization		(66,925	)		(61,881	)		(52,733	)
Interest on loans		(23,552	)		(18,920	)		—
Gains on cash flow hedges		(36,845	)		—			—
Other		(40,472	)		(30,211	)		(25,632	)
Gross deferred tax liabilities		(564,391	)		(352,693	)		(405,590	)
Net deferred tax asset	$	77,017		$	173,621		$	171,256

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 25 arise principally from operating losses before dividends from subsidiaries.

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

	Federal, State and Local Tax			Accrued Interest			Unrecognized Income Tax Benefits
	(In thousands)

Gross unrecognized tax benefits at January 1, 2017	$	35,889		$	7,915		$	43,804
Increases as a result of tax positions taken during 2017		13,019			—			13,019
Increases as a result of tax positions taken in prior years		—			1,379			1,379
Decreases as a result of settlements with taxing authorities		(332	)		(168	)		(500	)
Decreases as a result of tax positions taken in prior years		(3,144	)		(3,475	)		(6,619	)
Gross unrecognized tax benefits at December 31, 2017		45,432			5,651			51,083
Increases as a result of tax positions taken during 2018		13,426			—			13,426
Increases as a result of tax positions taken in prior years		—			1,969			1,969
Decreases as a result of settlements with taxing authorities		(664	)		(289	)		(953	)
Decreases as a result of tax positions taken in prior years		(1,920	)		(702	)		(2,622	)
Gross unrecognized tax benefits at December 31, 2018		56,274			6,629			62,903
Increases as a result of tax positions taken during 2019		6,996			—			6,996
Increases as a result of tax positions taken in prior years		3,265			3,255			6,520
Decreases as a result of tax positions taken in prior years		(7,566	)		(2,685	)		(10,251	)
Gross unrecognized tax benefits at December 31, 2019	$	58,969		$	7,199			66,168
Less: Federal, state and local income tax benefits								(13,208	)
Net unrecognized tax benefits at December 31, 2019 that, if recognized, would impact the effective income tax rate							$	52,960

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 balance of accrued interest at December 31, 2019 is included in the table above. 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 2018, although under statute the income tax returns from 2016 through 2018 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 2013. It is not reasonably possible to estimate when examinations for any subsequent years will be completed.

Earnings per common share

12 Months Ended

Dec. 31, 2018

Earnings Per Share [Abstract]

Earnings per common share

14. Earnings per common share

The computations of basic earnings per common share follow:

	Year Ended December 31
	2019			2018			2017
	(In thousands, except per share)
Income available to common shareholders:
Net income	$	1,929,149		$	1,918,080		$	1,408,306
Less: Preferred stock dividends(a)		(69,441	)		(72,521	)		(72,734	)
Net income available to common equity		1,859,708			1,845,559			1,335,572
Less: Income attributable to unvested stock-based compensation awards		(10,199	)		(9,531	)		(8,069	)
Net income available to common shareholders	$	1,849,509		$	1,836,028		$	1,327,503
Weighted-average shares outstanding:
Common shares outstanding (including common stock issuable) and unvested stock-based compensation awards		135,169			144,740			153,092
Less: Unvested stock-based compensation awards		(741	)		(748	)		(933	)
Weighted-average shares outstanding		134,428			143,992			152,159

Basic earnings per common share	$	13.76		$	12.75		$	8.72

(a)	Including impact of not as yet declared cumulative dividends.

The computations of diluted earnings per common share follow:

	Year Ended December 31
	2019			2018			2017
	(In thousands, except per share)

Net income available to common equity	$	1,859,708		$	1,845,559		$	1,335,572
Less: Income attributable to unvested stock-based compensation awards		(10,197	)		(9,524	)		(8,055	)
Net income available to common shareholders	$	1,849,511		$	1,836,035		$	1,327,517
Adjusted weighted-average shares outstanding:
Common and unvested stock-based compensation awards		135,169			144,740			153,092
Less: Unvested stock-based compensation awards		(741	)		(748	)		(933	)
Plus: Incremental shares from assumed conversion of stock-based compensation awards and warrants to purchase common stock		34			159			392
Adjusted weighted-average shares outstanding		134,462			144,151			152,551

Diluted earnings per common share	$	13.75		$	12.74		$	8.70

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 and warrants to purchase common stock of M&T representing common shares of 238,000 in 2019, 194,000 in 2018 and 401,000 in 2017 were not included in the computations of diluted earnings per common share because the effect on those years would have been antidilutive.

Comprehensive income

12 Months Ended

Dec. 31, 2019

Equity [Abstract]

Comprehensive income

15. Comprehensive income

In February 2018, the FASB issued accounting guidance related to reclassification of certain tax effects from AOCI so that following enactment of the Tax Act the tax effects of items within AOCI reflect the appropriate tax. The guidance provided for a reclassification from AOCI to retained earnings for the effect of remeasuring deferred tax assets and liabilities related to items within AOCI at the 21 percent corporate tax rate established by the Tax Act. The impact of that reclassification was an increase in retained earnings as of December 31, 2017 resulting from items remaining in AOCI as of that date as follows:

	(In thousands)

Net unrealized losses on investment securities	$	8,065
Defined benefit plans liability adjustments		53,960
Cash flow hedges and other		2,004
Increase to retained earnings	$	64,029

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						Total Amount				Income
	Securities (a)			Plans			Other			Before Tax				Tax			Net
	(In thousands)

Balance — January 1, 2019	$	(200,107	)		(354,502	)		(14,719	)	$	(569,328	)			149,247		$	(420,081	)
Other comprehensive income before reclassifications:
Unrealized holding gains, net		247,411			—			—			247,411				(65,009	)		182,402
Foreign currency translation adjustment		—			—			1,381			1,381				(290	)		1,091
Unrealized gains on cash flow hedges		—			—			160,373			160,373				(42,163	)		118,210
Current year benefit plans losses		—			(126,618	)		—			(126,618	)			33,287			(93,331	)
Total other comprehensive income (loss) before reclassifications		247,411			(126,618	)		161,754			282,547				(74,175	)		208,372
Amounts reclassified from accumulated other comprehensive income that (increase) decrease net income:
Amortization of unrealized holding losses on held-to-maturity (“HTM”) securities		3,394			—			—			3,394		(c)		(892	)		2,502
Losses realized in net income		3			—			—			3		(d)		(1	)		2
Accretion of net gain on terminated cash flow hedges		—			—			(136	)		(136	)	(e)		36			(100	)
Net yield adjustment from cash flow hedges currently in effect		—			—			(13,011	)		(13,011	)	(c)		3,421			(9,590	)
Amortization of prior service credit		—			(4,173	)		—			(4,173	)	(f)		1,097			(3,076	)
Amortization of actuarial losses		—			20,745			—			20,745		(f)		(5,454	)		15,291
Total other comprehensive income (loss)		250,808			(110,046	)		148,607			289,369				(75,968	)		213,401
Balance — December 31, 2019	$	50,701			(464,548	)		133,888		$	(279,959	)			73,279		$	(206,680	)

Balance — January 1, 2018	$	(59,957	)		(413,168	)		(20,165	)	$	(493,290	)			129,476		$	(363,814	)
Cumulative effect of change in accounting principle — equity securities (a)		(22,795	)		—			—			(22,795	)			5,942			(16,853	)
Other comprehensive income before reclassifications:
Unrealized holding losses, net		(121,589	)		—			—			(121,589	)			31,946			(89,643	)
Foreign currency translation adjustment		—			—			(2,817	)		(2,817	)			592			(2,225	)
Unrealized losses on cash flow hedges		—			—			(4,965	)		(4,965	)			1,306			(3,659	)
Current year benefit plans gains		—			19,871			—			19,871				(5,224	)		14,647
Total other comprehensive income (loss) before reclassifications		(121,589	)		19,871			(7,782	)		(109,500	)			28,620			(80,880	)
Amounts reclassified from accumulated other comprehensive income that (increase) decrease net income:
Amortization of unrealized holding losses on HTM securities		4,252			—			—			4,252		(c)		(1,118	)		3,134
Gains realized in net income		(18	)		—			—			(18	)	(d)		4			(14	)
Accretion of net gain on terminated cash flow hedges		—			—			(111	)		(111	)	(e)		29			(82	)
Net yield adjustment from cash flow hedges currently in effect		—			—			13,339			13,339		(c)		(3,507	)		9,832
Amortization of prior service credit		—			(4,172	)		—			(4,172	)	(f)		1,097			(3,075	)
Amortization of actuarial losses		—			42,967			—			42,967		(f)		(11,296	)		31,671
Total other comprehensive income (loss)		(117,355	)		58,666			5,446			(53,243	)			13,829			(39,414	)
Balance — December 31, 2018	$	(200,107	)		(354,502	)		(14,719	)	$	(569,328	)			149,247		$	(420,081	)

							Defined						Total
	Investment Securities						Benefit						Amount				Income
	With OTTI (b)			All Other			Plans			Other			Before Tax				Tax			Net
	(In thousands)

Balance — January 1, 2017	$	46,725			(73,785	)		(449,917	)		(8,268	)	$	(485,245	)			190,609		$	(294,636	)
Other comprehensive income before reclassifications:
Unrealized holding losses, net		(8,746	)		(6,259	)		—			—			(15,005	)			7,269			(7,736	)
Foreign currency translation adjustment		—			—			—			4,447			4,447				(2,206	)		2,241
Unrealized losses on cash flow hedges		—			—			—			(12,291	)		(12,291	)			4,837			(7,454	)
Current year benefit plans gains		—			—			9,276			—			9,276				(3,650	)		5,626
Total other comprehensive income (loss) before reclassifications		(8,746	)		(6,259	)		9,276			(7,844	)		(13,573	)			6,250			(7,323	)
Amounts reclassified from accumulated other comprehensive income that (increase) decrease net income:
Amortization of unrealized holding losses on HTM securities		—			3,387			—			—			3,387		(c)		(1,333	)		2,054
Gains realized in net income		(18,351	)		(2,928	)		—			—			(21,279	)	(d)		7,195			(14,084	)
Accretion of net gain on terminated cash flow hedges		—			—			—			(137	)		(137	)	(e)		54			(83	)
Net yield adjustment from cash flow hedges currently in effect		—			—			—			(3,916	)		(3,916	)	(c)		1,541			(2,375	)
Amortization of prior service credit		—			—			(802	)		—			(802	)	(f)		315			(487	)
Amortization of actuarial losses		—			—			28,275			—			28,275		(f)		(11,126	)		17,149
Total other comprehensive income (loss)		(27,097	)		(5,800	)		36,749			(11,897	)		(8,045	)			2,896			(5,149	)
Reclassification of income tax effects to retained earnings		—			—			—			—			—				(64,029	)		(64,029	)
Balance — December 31, 2017	$	19,628			(79,585	)		(413,168	)		(20,165	)	$	(493,290	)			129,476		$	(363,814	)

(a) Beginning January 1, 2018, equity securities with readily determinable market values are required to be measured at fair value with changes in fair value recognized in the income statement. Prior to that date, such changes in fair value were reflected in other comprehensive income. Separate presentation of investment securities with an other-than-temporary impairment change is no longer required.

(b) Other-than-temporary impairment.

(d) Included in gain (loss) on bank investment securities.

(e) Included in interest expense.

(f) Included in other costs of operations.

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

				Defined
	Investment Securities			Benefit Plans			Other			Total
	(In thousands)

Balance at January 1, 2017	$	(16,319	)	$	(272,874	)	$	(5,443	)	$	(294,636	)
Net gain (loss) during 2017		(19,766	)		22,288			(7,671	)		(5,149	)
Reclassification of income tax effects to retained earnings		(8,065	)		(53,960	)		(2,004	)		(64,029	)
Balance at December 31, 2017		(44,150	)		(304,546	)		(15,118	)		(363,814	)
Cumulative effect of change in accounting principle — equity securities		(16,853	)		—			—			(16,853	)
Net gain (loss) during 2018		(86,523	)		43,243			3,866			(39,414	)
Balance at December 31, 2018		(147,526	)		(261,303	)		(11,252	)		(420,081	)
Net gain (loss) during 2019		184,906			(81,116	)		109,611			213,401
Balance at December 31, 2019	$	37,380		$	(342,419	)	$	98,359		$	(206,680	)

Other income and other expense

12 Months Ended

Dec. 31, 2019

Other Income And Expenses [Abstract]

Other income and other expense

16. 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
	2019		2018		2017
	(In thousands)
Other income:
Credit-related fee income	$	86,792	$	82,614	$	77,580
Other expense:
Professional services		330,900		312,998		289,862
Accrual for Wilmington Trust Corporation legal-related matters				135,000
Amortization of capitalized mortgage servicing rights		71,888

Derivative financial instruments

12 Months Ended

Dec. 31, 2019

Derivative Instruments And Hedging Activities Disclosure [Abstract]

Derivative financial instruments

18. 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, 2019.

The net effect of interest rate swap agreements was to decrease net interest income by $2 million in 2019 and $25 million in 2018, and to increase net interest income by $25 million in 2017.

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


					Weighted-						Estimated
	Notional		Average		Average Rate						Fair Value
	Amount		Maturity		Fixed			Variable			Gain (Loss) (a)
	(In thousands)		(In years)								(In thousands)
December 31, 2019
Fair value hedges:
Fixed rate long-term borrowings (b)	$	3,800,000		2.2		2.51	%		2.27	%	$	(567	)
Cash flow hedges:
Interest payments on variable rate commercial real estate loans (b)(c)		53,750,000		1.4		2.44	%		1.73	%		(1,195	)
Total	$	57,550,000		1.5							$	(1,762	)
December 31, 2018
Fair value hedges:
Fixed rate long-term borrowings (b)	$	4,450,000		2.8		2.47	%		3.02	%	$	4,219
Cash flow hedges:
Interest payments on variable rate commercial real estate loans (b)(d)		15,400,000		1.3		1.52	%		2.35	%		1,311
Total	$	19,850,000		1.7							$	5,530

(a)

Certain clearinghouse exchange rules provide that required payments by counterparties for variation margin are treated as settlements of those positions. The impact of such settlements at December 31, 2019 was a reduction of estimated fair value gains on interest rate swap agreements designated as fair value hedges of $45.1 million and cash flow hedges of $140.7 million. The impact of such settlements at December 31, 2018 was a reduction of estimated fair value losses on agreements designated as fair value hedges of $54.7 million and cash flow hedges of $9.1 million.

(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 $40.4 billion of forward-starting interest rate swap agreements that will become effective in 2020-2022.

(d)	Includes notional amount and terms of $12.6 billion of forward-starting interest rate swap agreements.

The notional amount of interest rate swap agreements entered into for risk management purposes that were outstanding at December 31, 2019 mature as follows:

	(In thousands)
Year ending December 31:
2020	$	12,200,000
2021		28,350,000
2022		16,000,000
2023		500,000
2027		500,000
	$	57,550,000

The Company utilizes commitments to sell residential and commercial real estate loans to hedge the exposure to changes in the fair value of real estate loans held for sale. Such commitments have generally been designated as fair value hedges. The Company also utilizes commitments to sell real estate loans to offset the exposure to changes in fair value of certain commitments to originate real estate loans for sale.

Derivative financial instruments used for trading account purposes included interest rate contracts, foreign exchange and other option contracts, foreign exchange forward and spot contracts, and financial futures. Interest rate contracts entered into for trading account purposes had notional values of $48.6 billion and $42.9 billion at December 31, 2019 and 2018, respectively. The notional amounts of foreign currency and other option and futures contracts entered into for trading account purposes aggregated $1.2 billion and $763 million at December 31, 2019 and 2018, 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
	2019		2018		2019		2018
	(In thousands)
Derivatives designated and qualifying as hedging instruments
Interest rate swap agreements (a)	$	232	$	5,530	$	1,994	$	—
Commitments to sell real estate loans (a)		1,195		1,090		421		6,434
		1,427		6,620		2,415		6,434
Derivatives not designated and qualifying as hedging instruments
Mortgage-related commitments to originate real estate loans for sale (a)		11,965		9,304		1,225		1,592
Commitments to sell real estate loans (a)		3,074		3,702		3,548		4,535
Trading:
Interest rate contracts (b)		398,295		118,687		68,103		169,255
Foreign exchange and other option and futures contracts (b)		12,506		10,549		11,800		8,870
		425,840		142,242		84,676		184,252
Total derivatives	$	427,267	$	148,862	$	87,091	$	190,686

(a)	Asset derivatives are reported in other assets and liability derivatives are reported in other liabilities.

(b)

Asset derivatives are reported in trading account assets and liability derivatives are reported in other liabilities. The impact of variation margin settlement payments at December 31, 2019 and December 31, 2018 was a reduction of the estimated fair value of interest rate contracts in the trading account in an asset position of $43.3 million and $170.7 million, respectively, and in a liability position of $281.3 million and $49.7 million, respectively.

	Amount of Gain (Loss) Recognized
	Year Ended December 31, 2019					Year Ended December 31, 2018					Year Ended December 31, 2017
	Derivative		Hedged Item			Derivative			Hedged Item		Derivative			Hedged Item
	(In thousands)
Derivatives in fair value hedging relationships
Interest rate swap agreements:
Fixed rate long-term borrowings (a)	$	95,006		(94,742	)	$	(10,006	)		10,969	$	(52,392	)		51,628
Derivatives not designated as hedging instruments
Trading:
Interest rate contracts (b)	$	24,701				$	4,506				$	5,398
Foreign exchange and other option and futures contracts (b)		8,511					9,416					6,821
Total	$	33,212				$	13,922				$	12,219

(a)	Effective January 1, 2018, reported as an adjustment to interest expense. Prior to 2018, reported as other revenues from operations.

(b)	Reported as trading account and foreign exchange gains.

	Carrying Amount of the Hedged Item				Cumulative Amount of Fair Value Hedging Adjustment Increasing (Decreasing) the Carrying Amount of the Hedged Item
	December 31				December 31
	2019		2018		2019		2018
	(In thousands)
Location in the Consolidated Balance Sheet of the Hedged Items in Fair Value Hedges

Long-term debt	$	3,840,775	$	4,394,109	$	43,640	$	(51,102	)

The amount of gain (loss) recognized in the consolidated statement of income associated with derivatives designated as cash flow hedges was not material.

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. As a result of these activities, net unrealized pre-tax gains related to hedged loans held for sale, commitments to originate loans for sale and commitments to sell loans were approximately $18 million at each of December 31, 2019 and 2018. 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.

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, was $51 million and $21 million at December 31, 2019 and 2018, respectively, for which the Company was required to post collateral relating to those positions of $50 million and $18 million at December 31, 2019 and 2018, respectively. 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, 2019 was not significant. If the credit risk-related contingent features had been triggered on December 31, 2019, the Company would not have been required to post any additional collateral with counterparties.

The aggregate fair value of derivative financial instruments in an asset position, which are subject to enforceable master netting arrangements, was $6 million and $18 million at December 31, 2019 and 2018, respectively. Counterparties posted collateral relating to those positions of $5 million and $16 million at December 31, 2019 and 2018, respectively. Trading account 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 $84 million and $65 million at December 31, 2019 and 2018, 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.

Variable interest entities

12 Months Ended

Dec. 31, 2019

Text Block [Abstract]

Variable interest entities

19. Variable interest entities

The Company’s securitization activity has consisted of securitizing loans originated for sale into government issued or guaranteed mortgage-backed securities. The amounts of those securitizations in 2019, 2018 and 2017 are presented in the Company’s consolidated statement of cash flows. The Company has not recognized any losses as a result of having securitized assets.

As described in note 8, M&T has issued junior subordinated debentures payable to various trusts that have issued Capital 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, 2019 and 2018, the Company included the junior subordinated debentures as “long-term borrowings” in its consolidated balance sheet and recognized $23 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 8.

The Company has invested as a limited partner in various partnerships that collectively had total assets of approximately $1.5 billion at of December 31, 2019 and $1.1 billion at December 31, 2018. Those partnerships generally construct or acquire properties for which the investing partners are

eligible to receive certain federal income tax credits in accordance with government guidelines. Such investments may also 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 $748 million, including $414 million of unfunded commitments, at December 31, 2019 and $523 million, including $280 million of unfunded commitments, at December 31, 2018. Contingent commitments to provide additional capital contributions to these partnerships were not material at December 31, 2019. The Company has not provided financial or other support to the partnerships that was not contractually required. The Company’s maximum exposure to loss from its investments in such partnerships as of December 31, 2019 was $984 million, including possible recapture of certain 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.

Fair value measurements

12 Months Ended

Dec. 31, 2019

Fair Value Disclosures [Abstract]

Fair value measurements

20. 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, 2019.

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 assets and liabilities

Trading account assets and liabilities include 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 derivative trading account assets and liabilities using externally developed pricing models based on market observable inputs and, therefore, classifies such valuations as Level 2. 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.

Investment securities available for sale 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 considered to be 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

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.

The following tables present assets and liabilities at December 31, 2019 and 2018 measured at estimated fair value on a recurring basis:

	Fair Value Measurements		Level 1 (a)		Level 2 (a)		Level 3
	(In thousands)
December 31, 2019
Trading account assets	$	470,129	$	49,040	$	421,089	$	—
Investment securities available for sale:
U.S. Treasury and federal agencies		9,767		—		9,767		—
Obligations of states and political subdivisions		775		—		775		—
Mortgage-backed securities:
Government issued or guaranteed		6,180,940		—		6,180,940		—
Privately issued		16		—		—		16
Other debt securities		127,278		—		127,278		—
		6,318,776		—		6,318,760		16
Equity securities		140,041		100,637		39,404		—
Real estate loans held for sale		442,079		—		442,079		—
Other assets (b)		16,466		—		4,501		11,965
Total assets	$	7,387,491	$	149,677	$	7,225,833	$	11,981
Trading account liabilities	$	79,903	$	—	$	79,903	$	—
Other liabilities (b)		7,188		—		5,963		1,225
Total liabilities	$	87,091	$	—	$	85,866	$	1,225

December 31, 2018
Trading account assets	$	185,584	$	46,018	$	139,566	$	—
Investment securities available for sale:
U.S. Treasury and federal agencies		1,336,931		—		1,336,931		—
Obligations of states and political subdivisions		1,659		—		1,659		—
Mortgage-backed securities:
Government issued or guaranteed		7,216,991		—		7,216,991		—
Privately issued		22		—		—		22
Other debt securities		126,906		—		126,906		—
		8,682,509		—		8,682,487		22
Equity securities		93,917		71,989		21,928		—
Real estate loans held for sale		551,697		—		551,697		—
Other assets (b)		19,626		—		10,322		9,304
Total assets	$	9,533,333	$	118,007	$	9,406,000	$	9,326
Trading account liabilities	$	178,125	$	—	$	178,125	$	—
Other liabilities (b)		12,561		—		10,969		1,592
Total liabilities	$	190,686	$	—	$	189,094	$	1,592

(a)	There were no significant transfers between Level 1 and Level 2 of the fair value hierarchy during the years ended December 31, 2019 and 2018.

(b)	Comprised predominantly of interest rate swap agreements used for interest rate risk management (Level 2), commitments to sell real estate loans (Level 2) and commitments to originate real estate loans to be held for sale (Level 3).

The changes in Level 3 assets and liabilities measured at estimated fair value on a recurring basis during the years ended December 31, 2019, 2018 and 2017 were as follows:

	Investment Securities Available for Sale
	Privately Issued Mortgage-Backed Securities			Other Assets and Other Liabilities
	(In thousands)
2019
Balance — January 1, 2019	$	22		$	7,712
Total gains realized/unrealized:
Included in earnings		—			129,398		(b)
Settlements		(6	)		—
Transfers out of Level 3 (a)		—			(126,370	)	(c)
Balance — December 31, 2019	$	16			10,740
Changes in unrealized gains included in earnings related to assets still held at December 31, 2019	$	—			11,146		(b)

2018
Balance — January 1, 2018	$	28			8,303
Total gains realized/unrealized:
Included in earnings		—			58,740		(b)
Settlements		(6	)		—
Transfers out of Level 3 (a)		—			(59,331	)	(c)
Balance — December 31, 2018	$	22			7,712
Changes in unrealized gains included in earnings related to assets still held at December 31, 2018	$	—			7,386		(b)

2017
Balance — January 1, 2017	$	44			7,325
Total gains realized/unrealized:
Included in earnings		—			77,832		(b)
Settlements		(16	)		—
Transfers out of Level 3 (a)		—			(76,854	)	(c)
Balance — December 31, 2017	$	28			8,303
Changes in unrealized gains included in earnings related to assets still held at December 31, 2017	$	—			7,978		(b)

(a)	The Company’s policy for transfers between fair value levels is to recognize the transfer as of the actual date of the event or change in circumstances that caused the transfer.

(b)	Reported as mortgage banking revenues in the consolidated statement of income and includes the fair value of commitment issuances and expirations.

(c)	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 uncollectible 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 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 85% at December 31, 2019. 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 non-recurring 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. 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 $305 million at December 31, 2019, ($115 million and $190 million of which were classified as Level 2 and Level 3, respectively), $268 million at December 31, 2018 ($120 million and $148 million of which were classified as Level 2 and Level 3, respectively), and $210 million at December 31, 2017 ($145 million and $65 million of which were classified as Level 2 and Level 3, respectively). Changes in fair value recognized during the years ended December 31, 2019, 2018 and 2017 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 $110 million, $83 million and $56 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 $21 million and $28 million at December 31, 2019 and December 31, 2018, respectively. Changes in fair value recognized during the years ended December 31, 2019, 2018 and 2017 for foreclosed assets held by the Company at the end of each of those years were not material.

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, 2019 and 2018:

Fair Value

Valuation

Technique

Unobservable

Inputs/Assumptions

Range

(Weighted-

Average)

(In thousands)

December 31, 2019

Recurring fair value

measurements

Privately issued mortgage-

backed securities

Two independent pricing quotes

—

Net other assets (liabilities) (a)

10,740

Discounted cash flow

Commitment expirations

0%-99% (13%)

December 31, 2018

Recurring fair value

measurements

Privately issued mortgage-

backed securities

Two independent pricing quotes

—

Net other assets (liabilities) (a)

7,712

Discounted cash flow

Commitment expirations

0%-95% (13%)

(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, 2019
	Carrying Amount			Estimated Fair Value			Level 1		Level 2			Level 3
	(In thousands)
Financial assets:
Cash and cash equivalents	$	1,432,805			1,432,805			1,394,984		37,821			—
Interest-bearing deposits at banks		7,190,154			7,190,154			—		7,190,154			—
Federal funds sold		3,500			3,500			—		3,500			—
Trading account assets		470,129			470,129			49,040		421,089			—
Investment securities		9,497,251			9,539,540			100,637		9,351,793			87,110
Loans and leases:
Commercial loans and leases		23,838,168			23,510,908			—		—			23,510,908
Commercial real estate loans		35,541,914			35,517,180			—		28,338			35,488,842
Residential real estate loans		16,156,094			16,227,274			—		3,990,848			12,236,426
Consumer loans		15,386,693			15,413,262			—		—			15,413,262
Allowance for credit losses		(1,051,071	)		—			—		—			—
Loans and leases, net		89,871,798			90,668,624			—		4,019,186			86,649,438
Accrued interest receivable		333,142			333,142			—		333,142			—
Financial liabilities:
Noninterest-bearing deposits	$	(32,396,407	)		(32,396,407	)		—		(32,396,407	)		—
Savings and interest-checking deposits		(54,932,162	)		(54,932,162	)		—		(54,932,162	)		—
Time deposits		(5,757,456	)		(5,829,347	)		—		(5,829,347	)		—
Deposits at Cayman Islands office		(1,684,044	)		(1,684,044	)		—		(1,684,044	)		—
Short-term borrowings		(62,363	)		(62,363	)		—		(62,363	)		—
Long-term borrowings		(6,986,186	)		(7,063,165	)		—		(7,063,165	)		—
Accrued interest payable		(105,374	)		(105,374	)		—		(105,374	)		—
Trading account liabilities		(79,903	)		(79,903	)		—		(79,903	)		—
Other financial instruments:
Commitments to originate real estate loans for sale	$	10,740			10,740			—		—			10,740
Commitments to sell real estate loans		300			300			—		300			—
Other credit-related commitments		(136,470	)		(136,470	)		—		—			(136,470	)
Interest rate swap agreements used for interest rate risk management		(1,762	)		(1,762	)		—		(1,762	)		—

	December 31, 2018
	Carrying Amount			Estimated Fair Value			Level 1		Level 2			Level 3
				(In thousands)
Financial assets:
Cash and cash equivalents	$	1,605,439			1,605,439			1,528,302		77,137			—
Interest-bearing deposits at banks		8,105,197			8,105,197			—		8,105,197			—
Trading account assets		185,584			185,584			46,018		139,566			—
Investment securities		12,692,813			12,631,656			71,989		12,456,467			103,200
Loans and leases:
Commercial loans and leases		22,977,976			22,587,387			—		—			22,587,387
Commercial real estate loans		34,363,556			33,832,558			—		346,775			33,485,783
Residential real estate loans		17,154,446			16,974,545			—		3,920,447			13,054,098
Consumer loans		13,970,499			13,819,545			—		—			13,819,545
Allowance for credit losses		(1,019,444	)		—			—		—			—
Loans and leases, net		87,447,033			87,214,035			—		4,267,222			82,946,813
Accrued interest receivable		353,965			353,965			—		353,965			—
Financial liabilities:
Noninterest-bearing deposits	$	(32,256,668	)		(32,256,668	)		—		(32,256,668	)		—
Savings and interest-checking deposits		(50,963,744	)		(50,963,744	)		—		(50,963,744	)		—
Time deposits		(6,124,254	)		(6,201,957	)		—		(6,201,957	)		—
Deposits at Cayman Islands office		(811,906	)		(811,906	)		—		(811,906	)		—
Short-term borrowings		(4,398,378	)		(4,398,378	)		—		(4,398,378	)		—
Long-term borrowings		(8,444,914	)		(8,385,289	)		—		(8,385,289	)		—
Accrued interest payable		(95,274	)		(95,274	)		—		(95,274	)		—
Trading account liabilities		(178,125	)		(178,125	)		—		(178,125	)		—
Other financial instruments:
Commitments to originate real estate loans for sale	$	7,712			7,712			—		—			7,712
Commitments to sell real estate loans		(6,177	)		(6,177	)		—		(6,177	)		—
Other credit-related commitments		(131,688	)		(131,688	)		—		—			(131,688	)
Interest rate swap agreements used for interest rate risk management		5,530			5,530			—		5,530			—

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. Management believes that fair value estimates may not be comparable between financial institutions due to the wide range of permitted valuation techniques and numerous estimates which must be made. 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

Commitments and contingencies

12 Months Ended

Dec. 31, 2018

Commitments And Contingencies Disclosure [Abstract]

Commitments and contingencies

21. 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
	2019		2018
	(In thousands)
Commitments to extend credit
Home equity lines of credit	$	5,442,160		5,484,197
Commercial real estate loans to be sold		164,076		229,401
Other commercial real estate		9,029,608		7,556,722
Residential real estate loans to be sold		423,056		245,211
Other residential real estate		448,375		219,351
Commercial and other		16,170,731		14,363,803
Standby letters of credit		2,441,432		2,326,991
Commercial letters of credit		41,059		55,808
Financial guarantees and indemnification contracts		4,108,572		3,529,136
Commitments to sell real estate loans		906,037		940,692

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 $9.1 billion and $8.6 billion at December 31, 2019 and 2018, 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 and $3.4 billion at December 31, 2019 and 2018, respectively.

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 considered 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, 2019, the Company believes that its obligation to loan purchasers was not material to the Company’s consolidated financial position.

Wilmington Trust, N.A., a wholly owned bank subsidiary of M&T, provides retirement services, including serving in certain trustee roles relating to Employee Stock Ownership Plans (“ESOPs”). Beginning in 2010, the U.S. Department of Labor (“DOL”) announced that it would increase its focus on ESOP transactions, particularly with regard to valuation issues relating to ESOP transactions. Beginning in late 2013, Wilmington Trust, N.A. began receiving requests for information and subpoenas relating to certain ESOP transactions for which it acted as trustee. In June 2016, Wilmington Trust, N.A. received a DOL subpoena seeking information on its global ESOP trustee business. In addition to these investigations, the DOL has commenced three lawsuits against Wilmington Trust, N.A. relating to its role as trustee of three ESOP transactions. In July 2019, Wilmington Trust, N.A. reached a settlement in principle with the DOL to resolve certain pending DOL ESOP matters. Although a formal settlement agreement has yet to be finalized and executed, the Company does not expect that the agreed-upon settlement will have a material incremental impact on the Company’s consolidated financial position or results of operations. Wilmington Trust, N.A. is also currently a defendant in five pending private party lawsuits relating to its role as trustee for five ESOP transactions. Under applicable transaction documents, Wilmington Trust, N.A. may be entitled to indemnification by the ESOP plan sponsors. These matters could result in damages, settlements, penalties, restitution, reputational damage or additional costs and expenses.

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 $50 million. 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.

Segment information

12 Months Ended

Dec. 31, 2019

Segment Reporting [Abstract]

Segment information

22. Segment information

Reportable segments have been determined based upon the Company’s internal profitability reporting system, which is organized by strategic business unit. Certain strategic business units have been combined for segment information reporting purposes where the nature of the products and services, the type of customer and the distribution of those products and services are similar. The

reportable segments are Business Banking, Commercial Banking, Commercial Real Estate, Discretionary Portfolio, Residential Mortgage Banking and Retail Banking.

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 4. 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. Income statement amounts are in thousands of dollars. Balance sheet amounts are in millions of dollars.

	For the Years Ended December 31, 2019, 2018 and 2017
	Business Banking							Commercial Banking						Commercial Real Estate									Discretionary Portfolio
	2019		2018			2017		2019		2018		2017		2019			2018			2017			2019		2018			2017
Net interest income(a)	$	451,307	$	434,579		$	393,948	$	828,888	$	821,812	$	809,301	$	692,526		$	665,220		$	649,378		$	209,807	$	228,051		$	277,095
Noninterest income		113,855		111,600			112,512		289,558		288,908		283,447		214,970			183,955			169,966			26,919		(9,690	)		23,851
		565,162		546,179			506,460		1,118,446		1,110,720		1,092,748		907,496			849,175			819,344			236,726		218,361			300,946
Provision for credit losses		16,501		10,916			15,598		25,580		8,976		11,876		1,537			3,159			(7,524	)		3,608		6,683			31,119
Amortization of core deposit and other intangible assets		—		—			—		—		—		—		1,060			1,060			1,060			—		—			—
Depreciation and other amortization		412		382			393		554		496		509		25,560			25,852			24,410			263		187			279
Other noninterest expense		319,136		305,340			294,493		384,013		364,102		339,936		240,736			217,387			207,493			52,901		65,393			76,021
Income (loss) before taxes		229,113		229,541			195,976		708,299		737,146		740,427		638,603			601,717			593,905			179,954		146,098			193,527
Income tax expense (benefit)		60,617		61,279			80,043		187,835		198,229		303,556		152,977			148,807			229,770			36,342		29,872			58,559
Net income (loss)	$	168,496	$	168,262		$	115,933	$	520,464	$	538,917	$	436,871	$	485,626		$	452,910		$	364,135		$	143,612	$	116,226		$	134,968
Average total assets (in millions)	$	5,793	$	5,631		$	5,602	$	28,142	$	26,626	$	26,573	$	23,921		$	22,885		$	22,741		$	29,081	$	32,123		$	37,203
Capital expenditures (in millions)	$	1	$	—		$	—	$	2	$	—	$	—	$	—		$	—		$	1		$	—	$	1		$	—

	For the Years Ended December 31, 2019, 2018 and 2017
	Residential Mortgage Banking							Retail Banking						All Other									Total
	2019		2018			2017		2019		2018		2017		2019			2018			2017			2019		2018			2017
Net interest income(a)	$	20,008	$	13,933		$	30,328	$	1,389,788	$	1,351,165	$	1,210,066	$	537,940		$	557,542		$	410,928		$	4,130,264	$	4,072,302		$	3,781,044
Noninterest income		393,372		305,560			321,589		327,562		324,228		329,833		695,443			651,439			609,945			2,061,679		1,856,000			1,851,143
		413,380		319,493			351,917		1,717,350		1,675,393		1,539,899		1,233,383			1,208,981			1,020,873			6,191,943		5,928,302			5,632,187
Provision for credit losses		382		(2,178	)		1,254		122,135		112,572		107,412		6,257			(8,128	)		8,265			176,000		132,000			168,000
Amortization of core deposit and other intangible assets		—		—			—		—		—		—		18,430			23,462			30,306			19,490		24,522			31,366
Depreciation and other amortization		46,901		24,288			32,011		38,394		35,274		38,234		68,840			68,004			69,923			180,924		154,483			165,759
Other noninterest expense		274,414		241,624			247,639		839,636		789,783		758,153		1,157,432			1,125,428			1,019,465			3,268,268		3,109,057			2,943,200
Income (loss) before taxes		91,683		55,759			71,013		717,185		737,764		636,100		(17,576	)		215			(107,086	)		2,547,261		2,508,240			2,323,862
Income tax expense (benefit)		19,355		10,272			25,446		189,611		196,467		258,934		(28,625	)		(54,766	)		(40,752	)		618,112		590,160			915,556
Net income (loss)	$	72,328	$	45,487		$	45,567	$	527,574	$	541,297	$	377,166	$	11,049		$	54,981		$	(66,334	)	$	1,929,149	$	1,918,080		$	1,408,306
Average total assets (in millions)	$	2,611	$	2,161		$	2,355	$	15,083	$	13,656	$	12,702	$	14,953		$	13,877		$	13,684		$	119,584	$	116,959		$	120,860
Capital expenditures (in millions)	$	1	$	1		$	—	$	76	$	31	$	34	$	98		$	65		$	44		$	178	$	98		$	79

(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 $22,863,000 in 2019, $21,897,000 in 2018 and $34,570,000 in 2017 and is eliminated in “All Other” net interest income and income tax expense (benefit).

The Business Banking segment provides deposit, lending, cash management and other financial services to small businesses and professionals through the Company’s banking office network and several other delivery channels, including business banking centers, telephone banking, Internet banking and automated teller machines. The Commercial Banking segment provides a wide range of credit products and banking services to middle-market and large commercial customers, mainly within the markets the Company serves. Among the services provided by this segment are commercial lending and leasing, letters of credit, deposit products and cash management services. The Commercial Real Estate segment provides credit services which are secured by various types of multifamily residential and commercial real estate and deposit services to its customers. Activities of this segment include the origination, sales and servicing of commercial real estate loans. Commercial real estate loans held for sale are included in the Commercial Real Estate Segment. The Discretionary Portfolio segment includes securities; residential real estate loans and other assets; short-term and long-term borrowed funds; brokered deposits; and Cayman Islands branch deposits. This segment also provides foreign exchange services to customers. The Residential Mortgage Banking segment originates and services residential real estate loans for consumers and sells

substantially all originated loans in the secondary market to investors or to the Discretionary Portfolio segment. The segment periodically purchases servicing rights to loans that have been originated by other entities. Residential real estate loans held for sale are included in the Residential Mortgage Banking segment. The Retail Banking segment offers a variety of services to consumers through several delivery channels that include banking offices, automated teller machines, and telephone, mobile and Internet banking. The “All Other” category includes other operating activities of the Company that are not directly attributable to the reported segments; 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 acquisitions of financial institutions; merger-related gains and expenses resulting from acquisitions; the net impact of the Company’s internal funds transfer pricing methodology; eliminations of transactions between reportable segments; certain nonrecurring transactions; the residual effects of unallocated support systems and general and administrative expenses; and the impact of interest rate risk management strategies. The amount of intersegment activity eliminated in arriving at consolidated totals was included in the “All Other” category as follows:

	Year Ended December 31
	2019			2018			2017
	(In thousands)

Revenues	$	(48,559	)	$	(41,285	)	$	(43,941	)
Expenses		(18,218	)		(24,660	)		(32,623	)
Income taxes (benefit)		(7,976	)		(4,371	)		(4,606	)
Net income (loss)		(22,365	)		(12,254	)		(6,712	)

The Company conducts substantially all of its operations in the United States. There are no transactions with a single customer that in the aggregate result in revenues that exceed ten percent of consolidated total revenues.

Regulatory matters

12 Months Ended

Dec. 31, 2019

Banking And Thrift [Abstract]

Regulatory matters

23. 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, 2019, approximately $605 million 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 Board 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.

The bank subsidiaries are required to maintain reserves against certain deposit liabilities. During the maintenance periods that included December 31, 2019 and 2018, cash and due from banks and interest-earning deposits at banks included a daily average of $666 million and $684 million, respectively, for such 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, 2019, the required minimum and well capitalized capital ratios are as follows:

				Well
	Minimum			Capitalized
● Common equity Tier 1 ("CET1") to risk-weighted assets		4.5	%		6.5	%
● Tier 1 capital to risk-weighted assets		6.0	%		8.0	%
● Total capital to risk-weighted assets		8.0	%		10.0	%
● Leverage — Tier 1 capital to average total assets, as defined		4.0	%		5.0	%

In addition, capital regulations require a “capital conservation buffer” of 2.5% composed entirely of CET1 on top of the minimum risk-weighted asset ratios.

The capital ratios and amounts of the Company and its banking subsidiaries as of December 31, 2019 and 2018 are presented below:

	M&T (Consolidated)			M&T Bank			Wilmington Trust, N.A.
	(Dollars in thousands)
December 31, 2019:
Common equity Tier 1 capital
Amount	$	10,053,887		$	10,649,953		$	606,538
Ratio(a)		9.73	%		10.34	%		56.35	%
Tier 1 capital
Amount		11,303,836			10,649,953			606,538
Ratio(a)		10.94	%		10.34	%		56.35	%
Total capital
Amount		13,480,612			12,342,834			608,130
Ratio(a)		13.05	%		11.99	%		56.50	%
Leverage
Amount		11,303,836			10,649,953			606,538
Ratio(b)		9.59	%		9.08	%		13.12	%
December 31, 2018:
Common equity Tier 1 capital
Amount	$	9,960,811		$	10,636,136		$	585,767
Ratio(a)		10.13	%		10.84	%		60.69	%
Tier 1 capital
Amount		11,193,770			10,636,136			585,767
Ratio(a)		11.38	%		10.84	%		60.69	%
Total capital
Amount		13,454,137			12,475,296			589,671
Ratio(a)		13.68	%		12.72	%		61.10	%
Leverage
Amount		11,193,770			10,636,136			585,767
Ratio(b)		9.88	%		9.42	%		12.51	%

(a)	The ratio of capital to risk-weighted assets, 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

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 505
-Section 50
-Paragraph 1C
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
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-Section 50
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
-Topic 942
-SubTopic 505
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-URI http://asc.fasb.org/extlink&oid=117337116&loc=SL5958570-112826

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=117337116&loc=SL5958569-112826

Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
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-URI http://asc.fasb.org/extlink&oid=117337116&loc=SL5958577-112826

Reference 6: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 7: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 8: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 9: http://fasb.org/us-gaap/role/ref/legacyRef
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+ Details

Parent company financial statements

12 Months Ended

Dec. 31, 2019

Condensed Financial Information Of Parent Company Only Disclosure [Abstract]

Parent company financial statements

25. Parent company financial statements

Condensed Balance Sheet

	December 31
	2019		2018
	(In thousands)
Assets
Cash in subsidiary bank	$	83,531	$	40,609
Due from consolidated bank subsidiaries
Money-market savings		876,819		856,881
Current income tax receivable		1,261		1,117
Total due from consolidated bank subsidiaries		878,080		857,998
Investments in consolidated subsidiaries
Banks		15,732,008		15,491,277
Other		301,765		324,360
Investments in trust preferred entities (note 19)		23,022		23,241
Other assets		67,732		64,187
Total assets	$	17,086,138	$	16,801,672
Liabilities
Accrued expenses and other liabilities	$	74,235	$	63,719
Long-term borrowings		1,295,254		1,277,762
Total liabilities		1,369,489		1,341,481
Shareholders’ equity		15,716,649		15,460,191
Total liabilities and shareholders’ equity	$	17,086,138	$	16,801,672

Condensed Statement of Income

	Year Ended December 31
	2019			2018			2017
	(In thousands, except per share)
Income
Dividends from consolidated bank subsidiaries	$	2,025,000		$	1,250,000		$	1,540,000
Equity in earnings of Bayview Lending Group LLC		36,740			23,500			352
Other income		7,216			2,417			9,493
Total income		2,068,956			1,275,917			1,549,845
Expense
Interest on long-term borrowings		51,938			36,354			21,591
Other expense		25,236			23,894			19,636
Total expense		77,174			60,248			41,227
Income before income taxes and equity in undistributed income of subsidiaries		1,991,782			1,215,669			1,508,618
Income tax credits		8,313			8,446			26,453
Income before equity in undistributed income of subsidiaries		2,000,095			1,224,115			1,535,071
Equity in undistributed income of subsidiaries
Net income of subsidiaries		1,954,054			1,943,965			1,413,235
Less: dividends received		(2,025,000	)		(1,250,000	)		(1,540,000	)
Equity in undistributed income of subsidiaries		(70,946	)		693,965			(126,765	)
Net income	$	1,929,149		$	1,918,080		$	1,408,306
Net income per common share
Basic	$	13.76		$	12.75		$	8.72
Diluted		13.75			12.74			8.70

Condensed Statement of Cash Flows

	Year Ended December 31
	2019			2018			2017
	(In thousands)
Cash flows from operating activities
Net income	$	1,929,149		$	1,918,080		$	1,408,306
Adjustments to reconcile net income to net cash provided by operating activities
Equity in undistributed income of subsidiaries		70,946			(693,965	)		126,765
Provision for deferred income taxes		5,263			4,949			4,543
Net change in accrued income and expense		(34,525	)		(8,242	)		(170	)
Gain on sale of assets		—			—			(2,995	)
Net cash provided by operating activities		1,970,833			1,220,822			1,536,449
Cash flows from investing activities
Proceeds from sales or maturities of investment securities		100			—			—
Other, net		51,235			29,933			12,407
Net cash provided by investing activities		51,335			29,933			12,407
Cash flows from financing activities
Purchases of treasury stock		(1,349,785	)		(2,194,396	)		(1,205,905	)
Dividends paid — common		(552,138	)		(510,382	)		(457,402	)
Dividends paid — preferred		(67,454	)		(72,521	)		(72,734	)
Proceeds from long-term borrowings		—			748,595			—
Redemption of Series A and Series C preferred stock		(381,500	)		—			—
Proceeds from issuance of Series G preferred stock		396,000			—			—
Other, net		(4,431	)		45,913			34,524
Net cash used by financing activities		(1,959,308	)		(1,982,791	)		(1,701,517	)
Net increase (decrease) in cash and cash equivalents		62,860			(732,036	)		(152,661	)
Cash and cash equivalents at beginning of year		897,490			1,629,526			1,782,187
Cash and cash equivalents at end of year	$	960,350		$	897,490		$	1,629,526
Supplemental disclosure of cash flow information
Interest received during the year	$	1,752		$	2,219		$	2,313
Interest paid during the year		49,451			17,482			18,498
Income taxes received during the year		6,251			6,362			21,740

Recent accounting developments

12 Months Ended

Dec. 31, 2019

Accounting Changes And Error Corrections [Abstract]

Recent accounting developments

26. Recent accounting developments

The following table provides a description of accounting standards that were adopted by the Company in 2019 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 2019

Leases

The new guidance requires lessees to record a right-of-use asset and a lease liability for all leases with a term greater than 12 months. While the guidance requires all leases to be recognized in the balance sheet, there continues to be a differentiation between finance leases and operating leases for purposes of income statement recognition and cash flow statement presentation. For finance leases, interest on the lease liability and amortization of the right-of-use asset is recognized separately in the statement of income. Repayments of principal on those lease liabilities are classified within financing activities and payments of interest on the lease liability are classified within operating activities in the statement of cash flows. For operating leases, a single lease cost is recognized in the statement of income and allocated over the lease term, generally on a straight-line basis. All cash payments are presented within operating activities in the statement of cash flows. The accounting applied by lessors is largely unchanged, however, the guidance eliminates the accounting model for leveraged leases for leases that commence after the effective date of the guidance.

January 1, 2019

The Company adopted the guidance on January 1, 2019 and applied the guidance retrospectively at the beginning of the period of adoption. The Company occupies certain banking offices and uses certain equipment under noncancelable operating lease agreements which prior to the adoption of the guidance were not reflected in its consolidated balance sheet. Upon adoption, the Company recognized a right-of-use asset of $394 million and increased liabilities by $399 million as a result of recognizing lease liabilities in its consolidated balance sheet. The new guidance did not have a material impact on the Company’s consolidated statement of income.

Premium Amortization on Purchased Callable Debt Securities

The amended guidance requires the premium on callable debt securities to be amortized to the earliest call date. The amendments do not require an accounting change for securities held at a discount; the discount continues to be amortized to maturity.

January 1, 2019

The Company adopted the amended guidance effective January 1, 2019 and applied the modified retrospective approach for reporting purposes. The adoption did not have a material effect on the Company’s consolidated financial position nor on its results of operations.

Standard

Description

Required date

of adoption

Effect on consolidated financial statements

Standards Not Yet Adopted as of December 31, 2019

Measurement of Credit Losses on Financial Instruments

The amended guidance replaces the incurred loss model for determining the allowance for credit losses. The guidance requires financial assets measured at amortized cost to be presented at the net amount expected to be collected. The allowance for credit losses will represent a valuation account that is deducted from the amortized cost basis of the financial assets to present their net carrying value at the amount expected to be collected. The income statement will reflect the measurement of credit losses for newly recognized financial assets as well as expected increases or decreases of expected credit losses that have taken place during the period. When determining the allowance, expected credit losses over the contractual term of the financial asset(s) (taking into account prepayments) will be estimated considering relevant information about past events, current conditions, and reasonable and supportable forecasts that affect the collectibility of the reported amount. The amended guidance also requires recording an allowance for credit losses for purchased financial assets with a more-than-insignificant amount of credit deterioration since origination. The initial allowance for these assets will be added to the purchase price at acquisition rather than being reported as an expense. Subsequent changes in the allowance will be recorded through the income statement as an expense adjustment. In addition, the amended guidance requires credit losses relating to available-for-sale debt securities to be recorded through an allowance for credit losses. The calculation of credit losses for available-for-sale securities will be similar to how it is determined under existing guidance.

January 1, 2020

The Company has completed its development, validation, and implementation of models and processes used to estimate current expected credit losses as required by the credit losses guidance. The Company’s approach for estimating current expected credit losses for loans includes utilizing macro-economic assumptions to project losses over a two-year reasonable and supportable forecast period. Subsequent to the forecast period, the Company reverts to longer term historical loss experience to estimate expected credit losses over the remaining contractual life.

Based on portfolio composition, current economic conditions, and reasonable and supportable forecasts of future conditions, the Company recognized an increase to the allowance for credit losses of $132 million upon adoption of the standard on January 1, 2020 as compared with the allowance for credit losses recognized on its consolidated balance sheet at December 31, 2019.

The effect on the allowance for credit losses is primarily attributable to increases in reserves for residential mortgage loans and consumer loans, which generally have longer estimated lives as compared with commercial and commercial real estate loans. The adoption did not have a material effect on the allowance for credit losses on held-to-maturity debt securities as most of this portfolio consists of U.S. Treasury and federal agency securities.

Simplifying the Test for Goodwill Impairment

The amended guidance eliminates step 2 from the goodwill impairment test.

January 1, 2020

The Company adopted the amended guidance effective January 1, 2020 using a prospective transition method and will incorporate the guidance as necessary when circumstances arise for the guidance to be utilized. The Company does not expect the guidance will have a material impact on its consolidated financial statements, unless at some point in the future one of its reporting units were to fail step 1 of the goodwill impairment test.

Standard	Description	Required date of adoption	Effect on consolidated financial statements
Standards Not Yet Adopted as of December 31, 2019
Changes to the Disclosure Requirements for Fair Value Measurements	The amended guidance modifies the disclosure requirements on fair value measurements in Topic 820, Fair Value Measurements. The amendments are a result of the disclosure framework project that focuses on improvements to the effectiveness of disclosures in the notes to financial statements. The amendments remove, modify, and add certain disclosure requirements. The disclosure requirements being removed relating to public companies are (1) the amount and reason for transfers between Level 1 and Level 2 of the fair value hierarchy, (2) the policy for timing of transfers between levels, and (3) the valuation process for Level 3 fair value measurements. The disclosure requirements being modified relating to public companies are (1) for investments in certain entities that calculate net asset value, an entity is required to disclose the timing of liquidation of an investee’s asset and the date when restrictions from redemption might lapse only if the investee has communicated the timing to the entity or announced the timing publicly, and (2) the measurement uncertainty disclosure is to communicate information about the uncertainty in measurement as a result of the use of unobservable inputs. The disclosure requirements being added relating to public companies are (1) to disclose the changes in unrealized gains and losses for the period for recurring Level 3 fair value measurements, and (2) to disclose the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements.	January 1, 2020 Early adoption permitted	The Company adopted the amended guidance effective January 1, 2020 using a prospective transition method for the amendments relating to changes in unrealized gains and losses, the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements, and the narrative description of measurement uncertainty. The 2020 first quarter disclosures will reflect this prospective application. All other amendments will be applied retrospectively. The Company does not expect the guidance to have a material impact on its consolidated financial statements.
Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract	The amended guidance requires a hosting arrangement that is a service contract to follow the guidance in Subtopic 350-40 to determine which implementation costs to capitalize and which costs to expense.	January 1, 2020 Early adoption permitted	The Company adopted the amended guidance effective January 1, 2020 using a prospective transition method. The impact of the guidance on the Company’s consolidated financial statements will be dependent on the nature and amount of actual expenditures, but is not expected to be material.
Improvements to Related Party Guidance for VIEs	The amended guidance requires that indirect interests held through related parties in common control arrangements should be considered on a proportional basis for determining whether fees paid to decision makers and service providers are variable interests.	January 1, 2020 Early adoption permitted	The guidance did not have a material impact on the Company’s consolidated financial statements.

Standard	Description	Required date of adoption	Effect on consolidated financial statements
Standards Not Yet Adopted as of December 31, 2019
Changes to the Disclosure Requirements for Defined Benefit Plans	The amended guidance modifies the disclosure requirements for employers that sponsor defined benefit pension or other postretirement plans. The disclosure requirements being removed relating to public companies are (1) the amounts in accumulated other comprehensive income expected to be recognized as components of net periodic benefit cost over the next fiscal year, (2) the amount and timing of plan assets expected to be returned to the employer, (3) the 2001 disclosure requirement relating to Japanese Welfare Pension Insurance Law, (4) related party disclosures about the amount of future annual benefits covered by insurance, and (5) the effects of a one-percentage-point change in assumed health care cost trends on the benefit cost and obligation. The disclosure requirements being added relating to public companies are (1) the weighted-average interest crediting rates for cash balance plans , and (2) an explanation of the reasons for significant gains and losses related to changes in the benefit obligation for the period.	January 1, 2021 Early adoption permitted	The amendments should be applied retrospectively. The Company does not expect the guidance to have a material impact on its consolidated financial statements.
Clarifying the Interactions Between Equity Securities, Equity Method and Joint Ventures, and Derivatives and Hedging	The amendments clarify the following guidance: 1. That an entity should consider observable transactions that require it to either apply or discontinue the equity method of accounting for the purposes of applying the measurement alternative in the equity securities investments guidance immediately before applying or upon discontinuing the equity method of accounting. 2. For the purpose of applying the derivatives and hedging guidance an entity should not consider whether, upon the settlement of a forward contract or exercise of a purchased option, individually or with existing investments, the underlying securities would be accounted for under the equity method of accounting or the fair value option in accordance with the financial instruments guidance. An entity also would evaluate the remaining characteristics in the derivatives and hedging guidance to determine the accounting for those forward contracts and purchased options.	January 1, 2021 Early adoption permitted	The amendments should be applied on a prospective basis. The Company does not expect the guidance will have a material impact on its consolidated financial statements.

Standard

Description

Required date

of adoption

Effect on consolidated financial statements

Standards Not Yet Adopted as of December 31, 2019

Simplifying the Accounting for Income Taxes

The amendments remove the following exceptions for accounting for income taxes:

1. Exception to the incremental approach for intraperiod tax allocation when there is a loss from continuing operations and income or a gain from other items (for example, discontinued operations or other comprehensive income)

2. Exception to the requirement to recognize a deferred tax liability for equity method investments when a foreign subsidiary becomes an equity method investment

3. Exception to the ability not to recognize a deferred tax liability for a foreign subsidiary when a foreign equity method investment becomes a subsidiary

4. Exception to the general methodology for calculating income taxes in an interim period when a year-to-date loss exceeds the anticipated loss for the year.

The amendments also simplify the accounting for income taxes by doing the following:

1. Requiring that an entity recognize a franchise tax (or similar tax) that is partially based on income as an income-based tax and account for any incremental amount incurred as a non-income-based tax.

2. Requiring that an entity evaluate when a step up in the tax basis of goodwill should be considered part of the business combination in which the book goodwill was originally recognized and when it should be considered a separate transaction.

3. Specifying that an entity is not required to allocate the consolidated amount of current and deferred tax expense to a legal entity that is not subject to tax in its separate financial statements. However, an entity may elect to do so (on an entity-by-entity basis) for a legal entity that is both not subject to tax and disregarded by the taxing authority.

4. Requiring that an entity reflect the effect of an enacted change in tax laws or rates in the annual effective tax rate computation in the interim period that includes the enactment date.

5. Making minor Codification improvements for income taxes related to employee stock ownership plans and investments in qualified affordable housing projects accounted for using the equity method.

January 1, 2021

Early adoption permitted

The amendments related to separate financial statements of legal entities that are not subject to tax should be applied on a retrospective basis for all periods presented. The amendments related to changes in ownership of foreign equity method investments or foreign subsidiaries should be applied on a modified retrospective basis through a cumulative-effect adjustment to retained earnings as of the beginning of the fiscal year of adoption. The amendments related to franchise taxes that are partially based on income should be applied on either a retrospective basis for all periods presented or a modified retrospective basis through a cumulative-effect adjustment to retained earnings as of the beginning of the fiscal year of adoption. All other amendments should be applied on a prospective basis.

Early adoption of the amendments in an interim period would require recognition of any adjustments as of the beginning of the annual period that includes that interim period. Additionally, an early adoption election would require adoption of all the amendments in the same period. The Company is evaluating the impact that the guidance will have on its consolidated financial statements.

Significant accounting policies (Policies)	12 Months Ended
Significant accounting policies (Policies)	Dec. 31, 2019
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 25 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 19.
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 foreign exchange 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.” Investments in equity securities having readily determinable fair values are stated at fair value and, beginning in 2018, 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. Prior to 2018, equity securities with readily determinable fair values were classified as available for sale. Amortization of premiums and accretion of discounts for investment securities available for sale and held to maturity are included in interest income. Other securities are stated at cost and include stock of the Federal Reserve Bank of New York and the Federal Home Loan Bank (“FHLB”) of New York. Individual debt securities are written down through a charge to earnings when declines in value below the cost basis of a security are considered to be other than temporary. In cases where fair value is less than amortized cost and the Company intends to sell a debt security, it is more likely than not to be required to sell a debt security before recovery of its amortized cost basis, or the Company does not expect to recover the entire amortized cost basis of a debt security, an other-than-temporary impairment is considered to have occurred. If the Company intends to sell the debt security or more likely than not will be required to sell the security before recovery of its amortized cost basis, the other-than-temporary impairment is recognized in earnings equal to the entire difference between the debt security’s amortized cost basis and its fair value. If the Company does not expect to recover the entire amortized cost basis of the security, the Company does not intend to sell the security and it is not more likely than not that the Company will be required to sell the security before recovery of its amortized cost basis, the other-than-temporary impairment is separated into (a) the amount representing the credit loss and (b) the amount related to all other factors. The amount of the other-than-temporary impairment related to the credit loss is recognized in earnings while the amount related to other factors is recognized in other comprehensive income, net of applicable taxes. Subsequently, the Company accounts for the other-than-temporarily impaired debt security as if the security had been purchased on the measurement date of the other-than-temporary impairment at an amortized cost basis equal to the previous amortized cost basis less the other-than-temporary impairment 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 depends on whether the loans were originated by the Company or were acquired in a business combination. Originated loans and leases 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 principal or interest is delinquent 90 days, unless management determines that the loan status clearly warrants other treatment. Nonaccrual commercial 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. 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. 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. Loan balances are charged off when it becomes evident that such balances are not fully collectible. For commercial 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 collectible. 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. 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. 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 market 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.” Except for consumer and residential mortgage loans that are considered smaller balance homogenous loans and are evaluated collectively, the Company considers a loan to be impaired for purposes of applying GAAP when, based on current information and events, it is probable that the Company will be unable to collect all amounts according to the contractual terms of the loan agreement or the loan is delinquent 90 days. Regardless of loan type, the Company considers a loan to be impaired if it qualifies as a troubled debt restructuring. Impaired loans are classified as either nonaccrual or as loans renegotiated at below market rates which continue to accrue interest, provided that a credit assessment of the borrower’s financial condition results in an expectation of full repayment under the modified contractual terms. Certain loans greater than 90 days delinquent are not considered impaired 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 are generally not considered impaired. Impairment of a loan is measured based on the present value of expected future cash flows discounted at the loan’s effective interest rate, the loan’s observable market price, or the fair value of collateral if the loan is collateral-dependent. Interest received on impaired loans placed on nonaccrual status is generally applied to reduce the carrying value of the loan or, if principal is considered fully collectible, recognized as interest income. Residual value estimates for commercial leases are generally determined through internal or external reviews of the leased property. The Company reviews commercial lease residual values at least annually and recognizes residual value impairments deemed to be other than temporary. Loans and leases acquired in a business combination Loans acquired in a business combination subsequent to December 31, 2008 were initially recorded at fair value with no carry-over of an acquired entity’s previously established allowance for credit losses. Purchased impaired loans represent specifically identified loans with evidence of credit deterioration for which it was probable at acquisition that the Company would be unable to collect all contractual principal and interest payments. For purchased impaired loans and other loans acquired at a discount that was, in part, attributable to credit quality, the excess of cash flows expected at acquisition over the estimated fair value of acquired loans was recognized as interest income over the remaining lives of the loans. Subsequent decreases in the expected cash flows required the Company to evaluate the need for additions to the Company’s allowance for credit losses. Subsequent improvements in expected cash flows resulted first in the recovery of any related allowance for credit losses and then in recognition of additional interest income over the then-remaining lives of the 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 represents, in management’s judgment, the amount of losses inherent in the loan and lease portfolio as of the balance sheet date. The allowance is determined by management’s evaluation of the loan and lease portfolio based on such factors as the differing economic risks associated with each loan category, the current financial condition of specific borrowers, the economic environment in which borrowers operate, the level of delinquent loans, the value of any collateral and, where applicable, the existence of any guarantees or indemnifications. The effects of probable decreases in expected principal cash flows on loans acquired at a discount are also considered in the establishment of the allowance for credit losses.
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 “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 residential real estate property collateralizing a consumer mortgage loan upon either (1) the creditor obtaining legal title to the residential real estate property upon completion of a foreclosure or (2) the borrower conveying all interest in the residential 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 “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 typically 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.
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 of five to ten 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 (a) a hedge of the exposure to changes in the fair value of a recognized asset or liability or an unrecognized firm commitment, (b) a hedge of the exposure to variable cash flows of a forecasted transaction or (c) 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, beginning in 2018, 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. Prior to 2018, hedge ineffectiveness for fair value and cash flow hedges was recorded in “other revenues from operations” in the consolidated statement of income. In addition, for cash flow hedges, the effective portion of the derivative’s unrealized gain or loss was initially recorded as a component of other comprehensive income and subsequently reclassified into earnings when the forecasted transaction affected 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. 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 trading account assets or liabilities with resultant changes in fair value being recognized in “trading account and foreign exchange gains” in the consolidated statement of income.
Stock-based compensation	Stock-based compensation Stock-based compensation expense is recognized over the vesting period of the stock-based grant based on the estimated grant date value of the stock-based compensation, 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.

Investment securities (Tables)

12 Months Ended

Dec. 31, 2019

Investments Debt And Equity Securities [Abstract]

Amortized Cost and Estimated Fair Value of Investment Securities

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
	(In thousands)
December 31, 2019
Investment securities available for sale:
U.S. Treasury and federal agencies	$	9,742	$	41	$	16	$	9,767
Obligations of states and political subdivisions		776		2		3		775
Mortgage-backed securities:
Government issued or guaranteed		6,113,913		88,634		21,607		6,180,940
Privately issued		16		—		—		16
Other debt securities		133,829		2,046		8,597		127,278
		6,258,276		90,723		30,223		6,318,776
Investment securities held to maturity:
U.S. Treasury and federal agencies		249,862		286		—		250,148
Obligations of states and political subdivisions		4,140		16		—		4,156
Mortgage-backed securities:
Government issued or guaranteed		2,306,180		50,381		1,992		2,354,569
Privately issued		93,496		11,779		18,181		87,094
Other debt securities		3,239		—		—		3,239
		2,656,917		62,462		20,173		2,699,206
Total debt securities	$	8,915,193	$	153,185	$	50,396	$	9,017,982
Equity and other securities:
Readily marketable equity — at fair value	$	105,524	$	34,786	$	269	$	140,041
Other — at cost		381,517		—		—		381,517
Total equity and other securities	$	487,041	$	34,786	$	269	$	521,558

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
	(In thousands)
December 31, 2018
Investment securities available for sale:
U.S. Treasury and federal agencies	$	1,346,782	$	—	$	9,851	$	1,336,931
Obligations of states and political subdivisions		1,660		4		5		1,659
Mortgage-backed securities:
Government issued or guaranteed		7,383,340		15,754		182,103		7,216,991
Privately issued		24		—		2		22
Other debt securities		137,617		770		11,481		126,906
		8,869,423		16,528		203,442		8,682,509
Investment securities held to maturity:
U.S. Treasury and federal agencies		446,542		—		239		446,303
Obligations of states and political subdivisions		7,494		22		12		7,504
Mortgage-backed securities:
Government issued or guaranteed		2,745,776		4,165		55,111		2,694,830
Privately issued		113,160		12,345		22,327		103,178
Other debt securities		3,668		—		—		3,668
		3,316,640		16,532		77,689		3,255,483
Total debt securities	$	12,186,063	$	33,060	$	281,131	$	11,937,992
Equity and other securities:
Readily marketable equity — at fair value	$	77,440	$	17,295	$	818	$	93,917
Other — at cost		599,747		—		—		599,747
Total equity and other securities	$	677,187	$	17,295	$	818	$	693,664

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

As of December 31, 2019, 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
	Amortized Cost		Estimated Fair Value		A or Better		BBB		BB		B or Less		Not Rated
	(In thousands)

Obligations of states and political subdivisions	$	4,916	$	4,931	$	4,809	$	122	$	—	$	—	$	—
Privately issued mortgage-backed securities		93,512		87,110		8,015		8,768		—		20,671		49,656
Other debt securities		137,068		130,517		4,740		74,770		19,106		—		31,901
Total	$	235,496	$	222,558	$	17,564	$	83,660	$	19,106	$	20,671	$	81,557

Amortized Cost and Estimated Fair Value of Collateralized Mortgage Obligations

The amortized cost and estimated fair value of collateralized mortgage obligations included in mortgage-backed securities were as follows:

	December 31
	2019		2018
	(In thousands)
Collateralized mortgage obligations:
Amortized cost	$	94,817	$	115,171
Estimated fair value		88,410		105,155

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

At December 31, 2019, the amortized cost and estimated fair value of debt securities by contractual maturity were as follows:

	Amortized Cost		Estimated Fair Value
	(In thousands)
Debt securities available for sale:
Due in one year or less	$	4,418		4,427
Due after one year through five years		10,717		10,777
Due after five years through ten years		99,212		98,616
Due after ten years		30,000		24,000
		144,347		137,820
Mortgage-backed securities available for sale		6,113,929		6,180,956
	$	6,258,276		6,318,776
Debt securities held to maturity:
Due in one year or less	$	251,457		251,749
Due after one year through five years		2,545		2,555
Due after ten years		3,239		3,239
		257,241		257,543
Mortgage-backed securities held to maturity		2,399,676		2,441,663
	$	2,656,917		2,699,206

Investment Securities in Continuous Unrealized Loss Position

	Less Than 12 Months					12 Months or More
	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
	(In thousands)
December 31, 2019
Investment securities available for sale:
U.S. Treasury and federal agencies	$	1,406		(7	)		2,893		(9	)
Obligations of states and political subdivisions		—		—			277		(3	)
Mortgage-backed securities:
Government issued or guaranteed		117,299		(222	)		2,002,364		(21,385	)
Other debt securities		6,600		(354	)		56,313		(8,243	)
		125,305		(583	)		2,061,847		(29,640	)
Investment securities held to maturity:
Mortgage-backed securities:
Government issued or guaranteed		2,727		(5	)		145,235		(1,987	)
Privately issued		—		—			49,656		(18,181	)
		2,727		(5	)		194,891		(20,168	)
Total	$	128,032		(588	)		2,256,738		(49,808	)

December 31, 2018
Investment securities available for sale:
U.S. Treasury and federal agencies	$	273		(2	)		1,335,559		(9,849	)
Obligations of states and political subdivisions		629		(5	)		—		—
Mortgage-backed securities:
Government issued or guaranteed		405,558		(2,892	)		5,646,773		(179,211	)
Privately issued		22		(2	)		—		—
Other debt securities		53,478		(2,187	)		66,014		(9,294	)
		459,960		(5,088	)		7,048,346		(198,354	)
Investment securities held to maturity:
U.S. Treasury and federal agencies		446,303		(239	)		—		—
Obligations of states and political subdivisions		—		—			3,126		(12	)
Mortgage-backed securities:
Government issued or guaranteed		179,354		(989	)		2,082,723		(54,122	)
Privately issued		—		—			51,943		(22,327	)
		625,657		(1,228	)		2,137,792		(76,461	)
Total	$	1,085,617		(6,316	)		9,186,138		(274,815	)

Loans and leases (Tables)

12 Months Ended

Dec. 31, 2019

Receivables [Abstract]

Total Loans and Leases Outstanding

Total loans and leases outstanding were comprised of the following:

	December 31
	2019			2018
	(In thousands)
Loans
Commercial, financial, etc.	$	22,575,700		$	21,730,012
Real estate:
Residential		16,098,125			17,150,658
Commercial		26,718,325			25,666,200
Construction		9,010,297			8,823,635
Consumer		15,373,881			13,956,086
Total loans		89,776,328			87,326,591
Leases
Commercial		1,412,197			1,406,901
Total loans and leases		91,188,525			88,733,492
Less: unearned discount		(265,656	)		(267,015	)
Total loans and leases, net of unearned discount	$	90,922,869		$	88,466,477

Summary of Current, Past Due and Nonaccrual Loans

A summary of current, past due and nonaccrual loans as of December 31, 2019 and 2018 follows:

	Current		30-89 Days Past Due		Accruing Loans Past Due 90 Days or More (a)		Accruing Loans Acquired at a Discount Past Due 90 days or More (b)		Purchased Impaired (c)		Nonaccrual		Total
	(In thousands)
December 31, 2019
Commercial, financial, leasing, etc.	$	23,290,797		184,011		16,776		27		—		346,557	$	23,838,168
Real estate:
Commercial		26,311,414		165,579		6,740		—		15,601		158,474		26,657,808
Residential builder and developer		1,521,315		21,195		—		—		753		3,982		1,547,245
Other commercial construction		7,204,148		95,346		3,360		—		1,237		32,770		7,336,861
Residential		12,760,040		451,274		486,515		5,788		143,145		235,663		14,082,425
Residential — limited documentation		1,858,037		65,215		181		—		66,809		83,427		2,073,669
Consumer:
Home equity lines and loans		4,386,511		30,229		—		1,662		—		63,215		4,481,617
Recreational finance		5,484,997		36,827		—		99		—		14,219		5,536,142
Automobile		3,787,221		78,478		—		—		—		21,293		3,886,992
Other		1,395,240		45,978		5,156		32,056		—		3,512		1,481,942
Total	$	87,999,720		1,174,132		518,728		39,632		227,545		963,112	$	90,922,869

December 31, 2018
Commercial, financial, leasing, etc.	$	22,701,020		39,798		2,567		168		—		234,423	$	22,977,976
Real estate:
Commercial		25,250,983		134,474		11,457		10		9,769		203,672		25,610,365
Residential builder and developer		1,665,178		20,333		—		—		—		4,798		1,690,309
Other commercial construction		6,982,077		43,615		14,344		—		641		22,205		7,062,882
Residential		13,591,790		404,808		189,682		6,650		203,044		233,352		14,629,326
Residential — limited documentation		2,278,040		72,544		—		—		89,851		84,685		2,525,120
Consumer:
Home equity lines and loans		4,758,513		25,416		—		5,033		—		71,292		4,860,254
Recreational finance		4,085,781		29,947		—		235		—		11,199		4,127,162
Automobile		3,555,757		79,804		—		—		—		23,359		3,658,920
Other		1,271,811		15,598		4,477		27,654		—		4,623		1,324,163
Total	$	86,140,950		866,337		222,527		39,750		303,305		893,608	$	88,466,477

(a)	Excludes loans acquired at a discount.

(b)	Loans acquired at a discount that were recorded at fair value at acquisition date. This category does not include purchased impaired loans that are presented separately.

(c)	Accruing loans acquired at a discount that were impaired at acquisition date and recorded at fair value.

Outstanding Principal Balance and Carrying Amount of Loans and Included in Consolidated Balance Sheet

	December 31
	2019		2018
	(In thousands)

Outstanding principal balance	$	769,414	$	1,016,785
Carrying amount:
Commercial, financial, leasing, etc.		21,114		27,073
Commercial real estate		94,890		135,047
Residential real estate		341,807		473,511
Consumer		77,785		91,860
	$	535,596	$	727,491

Summary of Changes in Accretable Yield for Acquired Loans

A summary of changes in the accretable yield for loans acquired at a discount for the years ended December 31, 2019, 2018 and 2017 follows:

For the Year Ended December 31,	2019						2018						2017
	Purchased Impaired			Other Acquired			Purchased Impaired			Other Acquired			Purchased Impaired			Other Acquired
	(In thousands)

Balance at beginning of period	$	147,210		$	96,907		$	157,918		$	133,162		$	154,233		$	201,153
Interest income		(49,017	)		(36,452	)		(37,819	)		(63,856	)		(47,452	)		(82,605	)
Reclassifications from nonaccretable balance		36,718			15,534			27,111			22,849			51,137			16,437
Other (a)		—			(3,909	)		—			4,752			—			(1,823	)
Balance at end of period	$	134,911		$	72,080		$	147,210		$	96,907		$	157,918		$	133,162

(a)	Other changes in expected cash flows including changes in interest rates and prepayment assumptions.

Loan Modification Activities that were Considered Troubled Debt Restructurings

The tables that follow summarize the Company’s loan modification activities that were considered troubled debt restructurings for the years ended December 31, 2019, 2018 and 2017:

					Post-modification (a)
Year Ended December 31, 2019	Number		Pre- modification Recorded Investment		Principal Deferral		Interest Rate Reduction		Other		Combination of Concession Types		Total
	(Dollars in thousands)

Commercial, financial, leasing, etc.		150	$	63,715	$	10,485	$	—	$	—	$	52,871	$	63,356
Real estate:
Commercial		51		48,315		5,193		—		—		26,152		31,345
Residential builder and developer		2		1,330		1,068		—		—		—		1,068
Other commercial construction		3		1,559		—		—		—		1,500		1,500
Residential		83		21,695		10,819		—		—		11,907		22,726
Residential — limited documentation		6		1,409		399		—		—		1,044		1,443
Consumer:
Home equity lines and loans		41		4,127		176		—		—		4,004		4,180
Recreational finance		10		265		265		—		—		—		265
Automobile		66		1,141		1,076		—		—		65		1,141
Total		412	$	143,556	$	29,481	$	—	$	—	$	97,543	$	127,024

Year Ended December 31, 2018

Commercial, financial, leasing, etc.		203	$	102,445	$	50,490	$	803	$	6,210	$	45,411	$	102,914
Real estate:
Commercial		83		30,217		16,870		175		4,686		9,000		30,731
Other commercial construction		1		752		746		—		—		—		746
Residential		134		34,798		19,962		—		—		18,110		38,072
Residential — limited documentation		9		1,887		827		—		—		1,423		2,250
Consumer:
Home equity lines and loans		47		3,952		224		—		—		3,755		3,979
Recreational finance		7		202		202		—		—		—		202
Automobile		73		1,330		1,318		—		—		12		1,330
Total		557	$	175,583	$	90,639	$	978	$	10,896	$	77,711	$	180,224

					Post-modification (a)
Year Ended December 31, 2017	Number		Pre- modification Recorded Investment		Principal Deferral		Interest Rate Reduction		Other		Combination of Concession Types		Total
	(Dollars in thousands)

Commercial, financial, leasing, etc.		217	$	111,036	$	25,051	$	—	$	6,459	$	57,153	$	88,663
Real estate:
Commercial		83		44,924		17,039		—		868		22,975		40,882
Residential builder and developer		3		12,291		—		—		—		10,879		10,879
Other commercial construction		2		168		168		—		—		—		168
Residential		141		31,827		16,633		—		—		17,974		34,607
Residential — limited documentation		20		4,230		911		—		—		3,661		4,572
Consumer:
Home equity lines and loans		110		10,049		1,137		—		491		8,585		10,213
Recreational finance		9		160		160		—		—		—		160
Automobile		69		1,378		1,203		—		—		175		1,378
Total		654	$	216,063	$	62,302	$	—	$	7,818	$	121,402	$	191,522

(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
	2019			2018
	(In thousands)
Commercial leases:
Direct financings:
Lease payments receivable	$	1,164,567		$	1,155,464
Estimated residual value of leased assets		84,540			85,169
Unearned income		(106,780	)		(110,458	)
Investment in direct financings		1,142,327			1,130,175
Leveraged leases:
Lease payments receivable		82,065			85,007
Estimated residual value of leased assets		81,025			81,261
Unearned income		(31,596	)		(33,717	)
Investment in leveraged leases		131,494			132,551
Total investment in leases	$	1,273,821		$	1,262,726
Deferred taxes payable arising from leveraged leases	$	70,245		$	74,995

Minimum Future Lease Payments to be Received from Lease Financings

At December 31, 2019, the minimum future lease payments to be received from lease financings were as follows:

	(In thousands)
Year ending December 31:
2020	$	332,719
2021		297,875
2022		227,652
2023		161,296
2024		84,433
Later years		142,657
	$	1,246,632

Allowance for credit losses (Tables)

12 Months Ended

Dec. 31, 2019

Receivables [Abstract]

Changes in Allowance for Credit Losses

Changes in the allowance for credit losses for the years ended December 31, 2019, 2018 and 2017 were as follows:

	Commercial, Financial,			Real Estate
	Leasing, etc.			Commercial			Residential			Consumer			Unallocated			Total
	(In thousands)
2019
Beginning balance	$	330,055			341,655			69,125			200,564			78,045		$	1,019,444
Provision for credit losses		69,702			(10,726	)		(8,585	)		126,029			(420	)		176,000
Net charge-offs
Charge-offs		(58,244	)		(12,664	)		(12,711	)		(154,089	)		—			(237,708	)
Recoveries		24,581			3,936			8,204			56,614			—			93,335
Net charge-offs		(33,663	)		(8,728	)		(4,507	)		(97,475	)		—			(144,373	)
Ending balance	$	366,094			322,201			56,033			229,118			77,625		$	1,051,071

2018
Beginning balance	$	328,599			374,085			65,405			170,809			78,300		$	1,017,198
Provision for credit losses		33,967			(41,181	)		12,401			127,068			(255	)		132,000
Net charge-offs
Charge-offs		(60,414	)		(12,286	)		(15,345	)		(143,196	)		—			(231,241	)
Recoveries		27,903			21,037			6,664			45,883			—			101,487
Net (charge-offs) recoveries		(32,511	)		8,751			(8,681	)		(97,313	)		—			(129,754	)
Ending balance	$	330,055			341,655			69,125			200,564			78,045		$	1,019,444

2017
Beginning balance	$	330,833			362,719			61,127			156,288			78,030		$	988,997
Provision for credit losses		41,511			6,715			16,094			103,410			270			168,000
Net charge-offs
Charge-offs		(64,941	)		(7,931	)		(20,799	)		(130,927	)		—			(224,598	)
Recoveries		21,196			12,582			8,983			42,038			—			84,799
Net (charge-offs) recoveries		(43,745	)		4,651			(11,816	)		(88,889	)		—			(139,799	)
Ending balance	$	328,599			374,085			65,405			170,809			78,300		$	1,017,198

Impaired Loans and Leases

The following tables provide information with respect to loans and leases that were considered impaired as of December 31, 2019 and 2018 and for the years ended December 31, 2019, 2018 and 2017.

	December 31, 2019						December 31, 2018
	Recorded Investment		Unpaid Principal Balance		Related Allowance		Recorded Investment		Unpaid Principal Balance		Related Allowance
	(In thousands)
With an allowance recorded:
Commercial, financial, leasing, etc.	$	230,444		257,745		74,435		153,478		175,549		46,034
Real estate:
Commercial		60,745		73,026		7,713		110,253		125,117		11,937
Residential builder and developer		9,559		9,856		121		5,981		6,557		462
Other commercial construction		12,425		24,908		1,354		10,563		11,113		640
Residential		125,623		145,497		6,873		124,974		147,817		5,402
Residential — limited documentation		64,268		77,359		2,300		74,156		90,066		3,000
Consumer:
Home equity lines and loans		46,325		51,238		8,957		47,982		53,248		9,135
Recreational finance		5,270		9,579		1,095		6,138		9,163		1,261
Automobile		3,256		3,344		703		3,527		3,599		729
Other		4,542		8,341		915		5,203		8,380		1,046
		562,457		660,893		104,466		542,255		630,609		79,646
With no related allowance recorded:
Commercial, financial, leasing, etc.		139,127		152,132		—		105,507		136,128		—
Real estate:
Commercial		117,751		131,406		—		113,376		124,657		—
Residential builder and developer		3,378		3,378		—		2,593		2,602		—
Other commercial construction		20,345		21,306		—		11,710		11,880		—
Residential		18,090		23,365		—		15,379		20,496		—
Residential — limited documentation		4,985		8,348		—		5,631		9,796		—
		303,676		339,935		—		254,196		305,559		—
Total:
Commercial, financial, leasing, etc.		369,571		409,877		74,435		258,985		311,677		46,034
Real estate:
Commercial		178,496		204,432		7,713		223,629		249,774		11,937
Residential builder and developer		12,937		13,234		121		8,574		9,159		462
Other commercial construction		32,770		46,214		1,354		22,273		22,993		640
Residential		143,713		168,862		6,873		140,353		168,313		5,402
Residential — limited documentation		69,253		85,707		2,300		79,787		99,862		3,000
Consumer:
Home equity lines and loans		46,325		51,238		8,957		47,982		53,248		9,135
Recreational finance		5,270		9,579		1,095		6,138		9,163		1,261
Automobile		3,256		3,344		703		3,527		3,599		729
Other		4,542		8,341		915		5,203		8,380		1,046
Total	$	866,133		1,000,828		104,466		796,451		936,168		79,646

Interest Income Recognized on Impaired Loans

	Year Ended December 31, 2019						Year Ended December 31, 2018
			Interest Income Recognized						Interest Income Recognized
	Average Recorded Investment		Total		Cash Basis		Average Recorded Investment		Total		Cash Basis
	(In thousands)

Commercial, financial, leasing, etc.	$	303,712		8,960		8,960		263,018		7,873		7,873
Real estate:
Commercial		208,200		5,850		5,850		194,451		10,880		10,880
Residential builder and developer		10,863		357		357		8,699		1,779		1,779
Other commercial construction		26,440		634		634		11,467		3,474		3,474
Residential		142,400		9,200		3,567		129,593		8,386		3,456
Residential — limited documentation		74,399		5,463		881		82,854		6,118		1,723
Consumer:
Home equity lines and loans		47,168		1,639		270		48,591		1,698		289
Recreational finance		5,707		558		17		1,849		333		9
Automobile		3,445		214		72		9,262		690		69
Other		5,025		525		11		4,413		230		13
Total	$	827,359		33,400		20,619		754,197		41,461		29,565

	Year Ended December 31, 2017
			Interest Income Recognized
	Average Recorded Investment		Total		Cash Basis
	(In thousands)

Commercial, financial, leasing, etc.	$	240,157		3,894		3,894
Real estate:
Commercial		207,616		4,497		4,497
Residential builder and developer		16,209		6,419		6,419
Other commercial construction		15,142		1,001		1,001
Residential		110,646		7,177		3,406
Residential — limited documentation		93,097		5,981		1,607
Consumer:
Home equity lines and loans		47,323		1,681		400
Recreational finance		1,041		212		9
Automobile		15,045		1,025		81
Other		2,322		96		2
Total	$	748,598		31,983		21,316

Summary of Loan Grades

The following table summarizes the loan grades applied to the various classes of the Company’s commercial loans and commercial real estate loans.

			Real Estate
	Commercial,				Residential		Other
	Financial,				Builder and		Commercial
	Leasing, etc.		Commercial		Developer		Construction
	(In thousands)
December 31, 2019
Pass	$	22,595,821		25,728,725		1,419,162		7,092,799
Criticized accrual		895,790		770,609		124,101		211,292
Criticized nonaccrual		346,557		158,474		3,982		32,770
Total	$	23,838,168		26,657,808		1,547,245		7,336,861
December 31, 2018
Pass	$	21,693,705		24,539,706		1,546,002		6,890,562
Criticized accrual		1,049,848		866,987		139,509		150,115
Criticized nonaccrual		234,423		203,672		4,798		22,205
Total	$	22,977,976		25,610,365		1,690,309		7,062,882

Allocation of Allowance for Credit Losses on Basis of Company's Impairment Methodology

The allocation of the allowance for credit losses summarized on the basis of the Company’s impairment methodology was as follows:

	Commercial, Financial,		Real Estate
	Leasing, etc.		Commercial		Residential		Consumer		Total
	(In thousands)
December 31, 2019
Individually evaluated for impairment	$	74,435		9,188		9,173		11,670	$	104,466
Collectively evaluated for impairment		291,659		313,013		43,656		217,448		865,776
Purchased impaired		—		—		3,204		—		3,204
Allocated	$	366,094		322,201		56,033		229,118		973,446
Unallocated										77,625
Total									$	1,051,071
December 31, 2018
Individually evaluated for impairment	$	46,034		13,039		8,402		12,171	$	79,646
Collectively evaluated for impairment		284,021		328,616		48,326		188,393		849,356
Purchased impaired		—		—		12,397		—		12,397
Allocated	$	330,055		341,655		69,125		200,564		941,399
Unallocated										78,045
Total									$	1,019,444

Recorded Investment in Loans and Leases on Basis of Company's Impairment Methodology

The recorded investment in loans and leases summarized on the basis of the Company’s impairment methodology was as follows:

	Commercial, Financial,		Real Estate
	Leasing, etc.		Commercial		Residential		Consumer		Total
	(In thousands)
December 31, 2019
Individually evaluated for impairment	$	369,571		224,203		212,966		59,393	$	866,133
Collectively evaluated for impairment		23,468,597		35,300,120		15,733,174		15,327,300		89,829,191
Purchased impaired		—		17,591		209,954		—		227,545
Total	$	23,838,168		35,541,914		16,156,094		15,386,693	$	90,922,869
December 31, 2018
Individually evaluated for impairment	$	258,985		254,476		220,140		62,850	$	796,451
Collectively evaluated for impairment		22,718,991		34,098,670		16,641,411		13,907,649		87,366,721
Purchased impaired		—		10,410		292,895		—		303,305
Total	$	22,977,976		34,363,556		17,154,446		13,970,499	$	88,466,477

Premises and equipment (Tables)

12 Months Ended

Dec. 31, 2019

Property Plant And Equipment [Abstract]

Summary of Premises and Equipment

The detail of premises and equipment was as follows:

	December 31
	2019		2018
	(In thousands)
Land	$	96,118	$	97,082
Buildings		482,182		465,482
Leasehold improvements		262,438		240,731
Furniture and equipment — owned		739,724		669,782
Furniture and equipment — capital leases		14,232		18,582
		1,594,694		1,491,659
Less: accumulated depreciation and amortization
Owned assets		882,272		835,218
Capital leases		8,425		9,033
		890,697		844,251
Right of use assets — operating leases		436,927		—
Premises and equipment, net	$	1,140,924	$	647,408

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, 2019
	(Dollars in thousands)
Lease cost
Operating lease cost	$	100,669
Short-term lease cost		105
Variable lease cost		2,332
Total lease cost	$	103,106

Other information
Right-of-use assets obtained in exchange for new operating lease liabilities	$	132,219
Cash paid toward lease liabilities		101,869
Weighted-average remaining lease term	7 years
Weighted-average discount rate		3.01	%

Summary of Minimum Lease Payments Under Noncancelable Operating Leases

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

	(In thousands)
Year ending December 31:
2020	$	100,447
2021		95,199
2022		79,794
2023		62,766
2024		50,539
Later years		154,585
Total lease payments		543,330
Less: imputed interest		55,775
Total	$	487,555

Capitalized servicing assets (Tables)

12 Months Ended

Dec. 31, 2019

Transfers And Servicing [Abstract]

Servicing Asset at Amortized Cost

Changes in capitalized servicing assets were as follows:

	Residential Mortgage Loans									Commercial Mortgage Loans
For the Year Ended December 31,	2019			2018			2017			2019			2018			2017
	(In thousands)
Beginning balance	$	120,509		$	114,978		$	117,351		$	114,663		$	114,076		$	103,764
Originations		26,067			28,985			28,792			41,370			26,298			34,620
Purchases		144,326			454			699			—			—			—
Amortization		(46,491	)		(23,908	)		(31,864	)		(25,397	)		(25,711	)		(24,308	)
		244,411			120,509			114,978			130,636			114,663			114,076
Valuation allowance		(7,000	)		—			—			—			—			—
Ending balance, net	$	237,411		$	120,509		$	114,978		$	130,636		$	114,663		$	114,076

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

	Residential			Commercial
	(Dollars in thousands)

Weighted-average prepayment speeds		15.84	%
Impact on fair value of 10% adverse change	$	(16,555	)
Impact on fair value of 20% adverse change		(31,475	)
Weighted-average OAS		9.28	%
Impact on fair value of 10% adverse change	$	(8,070	)
Impact on fair value of 20% adverse change		(15,663	)
Weighted-average discount rate					18.00	%
Impact on fair value of 10% adverse change				$	(6,948	)
Impact on fair value of 20% adverse change					(13,395	)

Goodwill and other intangible assets (Tables)

12 Months Ended

Dec. 31, 2019

Goodwill And Intangible Assets Disclosure [Abstract]

Schedule of Finite-Lived Intangible Assets

Total amortizing intangible assets were comprised of the following:

	Gross Carrying Amount		Accumulated Amortization		Net Carrying Amount
	(In thousands)
December 31, 2019
Core deposit	$	131,664	$	105,802	$	25,862
Other		6,757		3,585		3,172
Total	$	138,421	$	109,387	$	29,034
December 31, 2018
Core deposit	$	887,459	$	843,572	$	43,887
Other		182,568		179,388		3,180
Total	$	1,070,027	$	1,022,960	$	47,067

Estimated Amortization Expense in Future Years

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

	(In thousands)
Year ending December 31:
2020	$	14,869
2021		10,167
2022		3,998
	$	29,034

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, 2019 and 2018 for purposes of testing for impairment is as follows:

	(In thousands)

Business Banking	$	864,366
Commercial Banking		1,401,873
Commercial Real Estate		654,389
Discretionary Portfolio		—
Residential Mortgage Banking		—
Retail Banking		1,309,191
All Other		363,293
Total	$	4,593,112

Borrowings (Tables)

12 Months Ended

Dec. 31, 2019

Debt Disclosure [Abstract]

Amounts and Interest Rates of Short-term Borrowings

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

	Federal Funds Purchased and Repurchase Agreements			Other Short-term Borrowings			Total
	(Dollars in thousands)
At December 31, 2019
Amount outstanding	$	62,363		$	—		$	62,363
Weighted-average interest rate		0.14	%		—			0.14	%
For the year ended December 31, 2019
Highest amount at a month-end	$	3,402,566		$	5,000,000
Daily-average amount outstanding		260,322			799,068		$	1,059,390
Weighted-average interest rate		1.86	%		2.49	%		2.34	%
At December 31, 2018
Amount outstanding	$	198,378		$	4,200,000		$	4,398,378
Weighted-average interest rate		1.68	%		2.63	%		2.58	%
For the year ended December 31, 2018
Highest amount at a month-end	$	2,654,416		$	4,200,000
Daily-average amount outstanding		261,200			69,465		$	330,665
Weighted-average interest rate		1.49	%		2.16	%		1.63	%
At December 31, 2017
Amount outstanding	$	175,099		$	—		$	175,099
Weighted-average interest rate		0.92	%		—			0.92	%
For the year ended December 31, 2017
Highest amount at a month-end	$	204,977		$	1,500,000
Daily-average amount outstanding		188,459			16,164		$	204,623
Weighted-average interest rate		0.69	%		1.27	%		0.74	%

Lines of Credit Under Formal Agreements

At December 31, 2019, M&T Bank had lines of credit under formal agreements as follows:

	(In thousands)

Outstanding borrowings	$	1,869
Unused		32,578,083

Long-term Borrowings

Long-term borrowings were as follows:

	December 31,
	2019		2018
	(In thousands)
Senior notes of M&T:
Variable rate due 2023	$	249,756	$	249,688
3.55% due 2023		520,454		506,021
Senior notes of M&T Bank:
Variable rate due 2021		349,893		349,794
Variable rate due 2022		249,758		249,658
2.25% due 2019		—		645,801
2.05% due 2020		749,254		737,793
2.10% due 2020		749,864		741,965
2.625% due 2021		654,136		646,301
2.50% due 2022		652,714		634,525
2.90% due 2025		749,572		749,488
Advances from FHLB:
Fixed rates		1,815		576,446
Agreements to repurchase securities		101,679		409,154
Subordinated notes of M&T Bank:
Variable rate due 2020		409,361		409,361
Variable rate due 2021		500,000		500,000
3.40% due 2027		514,353		481,692
Junior subordinated debentures of M&T associated with preferred capital securities:
Fixed rates:
BSB Capital Trust I — 8.125%, due 2028		15,728		15,705
Provident Trust I — 8.29%, due 2028		28,235		27,489
Southern Financial Statutory Trust I — 10.60%, due 2030		6,770		6,713
Variable rates:
First Maryland Capital I — due 2027		147,871		147,333
First Maryland Capital II — due 2027		149,943		149,280
Allfirst Asset Trust — due 2029		96,930		96,785
BSB Capital Trust III — due 2033		15,464		15,464
Provident Statutory Trust III — due 2033		55,867		55,143
Southern Financial Capital Trust III — due 2033		8,236		8,141
Other		8,533		35,174
	$	6,986,186	$	8,444,914

Maturity of Long-term Borrowings

Long-term borrowings at December 31, 2019 mature as follows:

	(In thousands)
Year ending December 31:
2020	$	2,010,251
2021		1,506,667
2022		907,794
2023		770,211
2024		479
Later years		1,790,784
	$	6,986,186

- 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.

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+ Details

Shareholders' equity (Tables)

12 Months Ended

Dec. 31, 2019

Equity [Abstract]

Issued and Outstanding Preferred Stock

Issued and outstanding preferred stock of M&T as of December 31, 2019 and 2018 is presented below:

	December 31, 2019				December 31, 2018
	Shares Issued and Outstanding		Carrying Value		Shares Issued and Outstanding		Carrying Value
	(Dollars in thousands)
Series A (a)
Fixed Rate Cumulative Perpetual Preferred Stock, $1,000 liquidation preference per share		—		—		230,000	$	230,000
Series C (a)
Fixed Rate Cumulative Perpetual Preferred Stock, $1,000 liquidation preference per share		—		—		151,500	$	151,500
Series E (b)
Fixed-to-Floating Rate Non-cumulative Perpetual Preferred Stock, $1,000 liquidation preference per share		350,000	$	350,000		350,000	$	350,000
Series F (c)
Fixed-to-Floating Rate Non-cumulative Perpetual Preferred Stock, $10,000 liquidation preference per share		50,000	$	500,000		50,000	$	500,000
Series G (d)
Fixed-Rate Reset Non-cumulative Perpetual Preferred Stock, $10,000 liquidation preference per share		40,000	$	400,000		—		—

(a)	The shares were fully redeemed in August 2019, having received the approval of the Federal Reserve to redeem such shares after issuing the Series G preferred stock. Declared dividends per share were $47.8125 in 2019 and $63.75 in each of 2018 and 2017.

(b)

(c)

(d)

- 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.

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+ Details

Revenue from contracts with customers (Tables)

12 Months Ended

Dec. 31, 2019

ASU 2014-09 [Member]

Summary of Sources of Noninterest Income that are Subject to Noted Accounting Guidance

The following tables summarize sources of the Company’s noninterest income during 2019 and 2018 that are subject to the amended guidance.

	Business Banking		Commercial Banking		Commercial Real Estate		Discretionary Portfolio		Residential Mortgage Banking		Retail Banking		All Other		Total
Year Ended December 31, 2019	(In thousands)

Classification in consolidated statement of income
Service charges on deposit accounts	$	60,690		93,044		9,828		—		4		263,659		5,753	$	432,978
Trust income		31		963		—		—		—		—		571,614		572,608
Brokerage services income		—		—		—		—		—		—		48,922		48,922
Other revenues from operations:
Merchant discount and credit card fees		36,844		52,161		2,516		—		—		12,140		3,381		107,042
Other		—		7,498		8,615		1,776		3,492		36,144		34,088		91,613
	$	97,565		153,666		20,959		1,776		3,496		311,943		663,758	$	1,253,163
Year Ended December 31, 2018

Classification in consolidated statement of income
Service charges on deposit accounts	$	62,323		96,407		9,870		—		10		254,590		6,137	$	429,337
Trust income		9		917		—		—		—		—		536,659		537,585
Brokerage services income		—		—		—		—		—		—		51,069		51,069
Other revenues from operations:
Merchant discount and credit card fees		34,557		52,051		2,213		—		—		14,924		2,208		105,953
Other		—		8,796		7,259		1,738		3,814		38,529		30,233		90,369
	$	96,889		158,171		19,342		1,738		3,824		308,043		626,306	$	1,214,313

Stock-based compensation plans (Tables)

12 Months Ended

Dec. 31, 2019

Disclosure Of Compensation Related Costs Sharebased Payments [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, 2019		556,875		$	170.07		179,439		$	144.18
Granted		448,487			164.63		—			—
Vested		(298,243	)		157.90		(113,894	)		133.69
Cancelled		(15,892	)		173.48		(1,954	)		161.42
Unvested at December 31, 2019		691,227		$	171.72		63,591		$	162.45

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 thousands)

Outstanding at January 1, 2019		220,591		$	157.98
Granted		164,244			164.54
Exercised		(76,181	)		122.55
Expired		(3,202	)		176.41
Outstanding at December 31, 2019		305,452		$	170.15		8.0	$	2,301
Exercisable at December 31, 2019		66,076		$	159.96		5.1	$	1,454

Pension plans and other postretirement benefits (Tables)

12 Months Ended

Dec. 31, 2019

Compensation And Retirement Disclosure [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
	2019			2018			2017
	(In thousands)

Service cost	$	17,294		$	20,346		$	20,193
Interest cost on benefit obligation		81,579			74,704			79,270
Expected return on plan assets		(122,139	)		(123,127	)		(108,524	)
Amortization of prior service cost		557			557			557
Recognized net actuarial loss		21,992			43,793			29,263
Net periodic pension cost (benefit)	$	(717	)	$	16,273		$	20,759

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

	Year Ended December 31
	2019			2018			2017
	(In thousands)

Service cost	$	859		$	938		$	1,172
Interest cost on benefit obligation		2,344			2,293			3,716
Amortization of prior service credit		(4,730	)		(4,729	)		(1,359	)
Recognized net actuarial gain		(1,247	)		(826	)		(988	)
Net other postretirement benefits cost (benefit)	$	(2,774	)	$	(2,324	)	$	2,541

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
	2019			2018			2019			2018
	(In thousands)
Change in benefit obligation:
Benefit obligation at beginning of year	$	1,949,613		$	2,188,736		$	59,991		$	68,637
Service cost		17,294			20,346			859			938
Interest cost		81,579			74,704			2,344			2,293
Plan participants’ contributions		—			—			2,749			2,974
Actuarial (gain) loss		298,713			(228,897	)		(687	)		(4,758	)
Medicare Part D reimbursement		—			—			370			508
Benefits paid		(99,870	)		(105,276	)		(9,134	)		(10,601	)
Benefit obligation at end of year		2,247,329			1,949,613			56,492			59,991
Change in plan assets:
Fair value of plan assets at beginning of year		1,833,833			2,014,891			—			—
Actual return on plan assets		293,546			(90,657	)		—			—
Employer contributions		10,431			14,875			6,015			7,119
Plan participants’ contributions		—			—			2,749			2,974
Medicare Part D reimbursement		—			—			370			508
Benefits paid		(99,870	)		(105,276	)		(9,134	)		(10,601	)
Fair value of plan assets at end of year		2,037,940			1,833,833			—			—
Funded status	$	(209,389	)	$	(115,780	)	$	(56,492	)	$	(59,991	)
Accrued liabilities recognized in the consolidated balance sheet	$	(209,389	)	$	(115,780	)	$	(56,492	)	$	(59,991	)
Amounts recognized in accumulated other comprehensive income (“AOCI”) were:
Net loss (gain)	$	507,029		$	401,716		$	(17,308	)	$	(17,868	)
Net prior service cost (credit)		1,834			2,391			(27,007	)		(31,737	)
Pre-tax adjustment to AOCI		508,863			404,107			(44,315	)		(49,605	)
Taxes		(133,779	)		(106,240	)		11,650			13,041
Net adjustment to AOCI	$	375,084		$	297,867		$	(32,665	)	$	(36,564	)

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.

	Pension Plans			Other Postretirement Benefit Plans			Total
	(In thousands)
2019
Net loss (gain)	$	127,305		$	(687	)	$	126,618
Amortization of prior service (cost) credit		(557	)		4,730			4,173
Amortization of actuarial (loss) gain		(21,992	)		1,247			(20,745	)
Total recognized in other comprehensive income, pre-tax	$	104,756		$	5,290		$	110,046
2018
Net gain	$	(15,113	)	$	(4,758	)	$	(19,871	)
Amortization of prior service (cost) credit		(557	)		4,729			4,172
Amortization of actuarial (loss) gain		(43,793	)		826			(42,967	)
Total recognized in other comprehensive income, pre-tax	$	(59,463	)	$	797		$	(58,666	)

Amortization of Amounts in Accumulated Other Comprehensive Income Expected to be Recognized as Components of Net Periodic Benefit Expense

The following table reflects the amortization of amounts in accumulated other comprehensive income expected to be recognized as components of net periodic benefit expense during 2020:

	Pension Plans		Other Postretirement Benefit Plans
	(In thousands)

Amortization of net prior service cost (credit)	$	557	$	(4,738	)
Amortization of net loss (gain)		55,851		(1,223	)

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
	2019			2018			2019			2018

Discount rate		3.25	%		4.25	%		3.25	%		4.25	%
Rate of increase in future compensation levels		4.29	%		4.31	%		—			—

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
	2019			2018			2017			2019			2018			2017

Discount rate		4.25	%		3.50	%		4.00	%		4.25	%		3.50	%		4.00	%
Long-term rate of return on plan assets		6.50	%		6.50	%		6.50	%		—			—			—
Rate of increase in future compensation levels		4.31	%		4.33	%		4.39	%		—			—			—

Effects on One-Percentage Point Change in Assumed Health Care Cost Trend Rates

A one-percentage point change in assumed health care cost trend rates would have had the following effects:

	+1%			-1%
	(In thousands)
Increase (decrease) in:
Service and interest cost	$	49	$	(45	)
Accumulated postretirement benefit obligation		834		(747	)

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

The fair values of the Company’s pension plan assets at December 31, 2019 and 2018, by asset category, were as follows:

	Fair Value Measurement of Plan Assets At December 31, 2019
	Total		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
	(In thousands)
Asset category:
Money-market investments	$	38,461	$	33,870	$	4,591	$	—
Equity securities:
M&T		148,603		148,603		—		—
Domestic(a)		219,663		219,663		—		—
International(b)		10,476		10,476		—		—
Mutual funds:
Domestic(a)		238,872		238,872		—		—
International(b)		381,433		381,433		—		—
		999,047		999,047		—		—
Debt securities:
Corporate(c)		112,783		—		112,783		—
Government		190,679		—		190,679		—
International		6,648		—		6,648		—
Mutual funds:
Domestic(d)		249,075		249,075		—		—
		559,185		249,075		310,110		—
Other:
Diversified mutual fund		86,980		86,980		—		—
Real estate partnerships		21,905		3,939		—		17,966
Private equity / debt		87,966		—		—		87,966
Hedge funds		231,807		116,029		—		115,778
Guaranteed deposit fund		10,527		—		—		10,527
		439,185		206,948		—		232,237
Total(e)	$	2,035,878	$	1,488,940	$	314,701	$	232,237

	Fair Value Measurement of Plan Assets At December 31, 2018
	Total		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
	(In thousands)
Asset category:
Money-market investments	$	23,049	$	10,794	$	12,255	$	—
Equity securities:
M&T		125,299		125,299		—		—
Domestic(a)		191,640		191,640		—		—
International(b)		7,752		7,752		—		—
Mutual funds:
Domestic(a)		216,523		216,523		—		—
International(b)		316,923		316,923		—		—
		858,137		858,137		—		—
Debt securities:
Corporate(c)		103,672		—		103,672		—
Government		182,034		—		182,034		—
International		2,140		—		2,140		—
Mutual funds:
Domestic(d)		280,902		280,902		—		—
International		20,661		20,661		—		—
		589,409		301,563		287,846		—
Other:
Diversified mutual fund		74,446		74,446		—		—
Real estate partnerships		11,807		2,791		—		9,016
Private equity / debt		63,699		—		—		63,699
Hedge funds		200,811		125,309		—		75,502
Guaranteed deposit fund		10,415		—		—		10,415
		361,178		202,546		—		158,632
Total(e)	$	1,831,773	$	1,373,040	$	300,101	$	158,632

(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 $2 million at each of December 31, 2019 and 2018.

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, 2019 were as follows:

	Balance – January 1, 2019		Purchases (Sales)		Total Realized/ Unrealized Gains (Losses)		Balance – December 31, 2019
	(In thousands)
Other
Real estate partnerships	$	9,016	$	7,623	$	1,327	$	17,966
Private equity/debt		63,699		9,531		14,736		87,966
Hedge funds		75,502		27,000		13,276		115,778
Guaranteed deposit fund		10,415		—		112		10,527
Total	$	158,632	$	44,154	$	29,451	$	232,237

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:

	Pension Benefits		Other Postretirement Benefits
	(In thousands)
Year ending December 31:
2020	$	100,800	$	6,622
2021		104,385		4,036
2022		107,368		3,972
2023		111,990		3,904
2024		115,962		3,829
2025 through 2029		619,663		17,919

Income taxes (Tables)

12 Months Ended

Dec. 31, 2019

Income Tax Disclosure [Abstract]

Components of Income Tax Expense

The components of income tax expense were as follows:

	Year Ended December 31
	2019		2018			2017
	(In thousands)
Current
Federal	$	359,668	$	408,428		$	363,043
State and local		132,696		113,706			94,714
Total current		492,364		522,134			457,757
Deferred
Federal		40,769		(12,780	)		367,308
State and local		16,779		28,637			33,482
Total deferred		57,548		15,857			400,790
Amortization of investments in qualified affordable housing projects		68,200		52,169			57,009
Total income taxes applicable to pre-tax income	$	618,112	$	590,160		$	915,556

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
	2019			2018			2017
	(In thousands)

Income taxes at statutory federal income tax rate	$	534,925		$	526,730		$	813,352
Increase (decrease) in taxes:
Tax-exempt income		(27,319	)		(26,186	)		(40,778	)
State and local income taxes, net of federal income tax effect		118,085			112,451			83,327
Qualified affordable housing project federal tax credits, net		(15,324	)		(12,240	)		(16,015	)
Initial impact of enactment of Tax Act		—			—			85,431
Other		7,745			(10,595	)		(9,761	)
	$	618,112		$	590,160		$	915,556

Deferred Tax Assets (Liabilities)

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

	2019			2018			2017
	(In thousands)

Losses on loans and other assets	$	309,523		$	322,818		$	345,609
Operating lease liabilities		128,178			—			—
Retirement benefits		55,048			30,057			45,322
Postretirement and other employee benefits		24,023			23,563			26,009
Incentive and other compensation plans		26,861			24,796			25,050
Interest on loans		—			—			37,900
Stock-based compensation		27,912			26,759			26,676
Unrealized losses		—			52,580			—
Losses on cash flow hedges		—			1,861			4,033
Other		69,863			43,880			66,247
Gross deferred tax assets		641,408			526,314			576,846
Right of use assets and other leasing transactions		(326,626	)		(186,787	)		(181,159	)
Unrealized gains		(13,322	)		—			(94,285	)
Capitalized servicing rights		(56,649	)		(54,894	)		(51,781	)
Depreciation and amortization		(66,925	)		(61,881	)		(52,733	)
Interest on loans		(23,552	)		(18,920	)		—
Gains on cash flow hedges		(36,845	)		—			—
Other		(40,472	)		(30,211	)		(25,632	)
Gross deferred tax liabilities		(564,391	)		(352,693	)		(405,590	)
Net deferred tax asset	$	77,017		$	173,621		$	171,256

Reconciliation of Beginning and Ending Amount of Unrecognized Tax Benefits

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

	Federal, State and Local Tax			Accrued Interest			Unrecognized Income Tax Benefits
	(In thousands)

Gross unrecognized tax benefits at January 1, 2017	$	35,889		$	7,915		$	43,804
Increases as a result of tax positions taken during 2017		13,019			—			13,019
Increases as a result of tax positions taken in prior years		—			1,379			1,379
Decreases as a result of settlements with taxing authorities		(332	)		(168	)		(500	)
Decreases as a result of tax positions taken in prior years		(3,144	)		(3,475	)		(6,619	)
Gross unrecognized tax benefits at December 31, 2017		45,432			5,651			51,083
Increases as a result of tax positions taken during 2018		13,426			—			13,426
Increases as a result of tax positions taken in prior years		—			1,969			1,969
Decreases as a result of settlements with taxing authorities		(664	)		(289	)		(953	)
Decreases as a result of tax positions taken in prior years		(1,920	)		(702	)		(2,622	)
Gross unrecognized tax benefits at December 31, 2018		56,274			6,629			62,903
Increases as a result of tax positions taken during 2019		6,996			—			6,996
Increases as a result of tax positions taken in prior years		3,265			3,255			6,520
Decreases as a result of tax positions taken in prior years		(7,566	)		(2,685	)		(10,251	)
Gross unrecognized tax benefits at December 31, 2019	$	58,969		$	7,199			66,168
Less: Federal, state and local income tax benefits								(13,208	)
Net unrecognized tax benefits at December 31, 2019 that, if recognized, would impact the effective income tax rate							$	52,960

Earnings per common share (Tables)

12 Months Ended

Dec. 31, 2018

Earnings Per Share [Abstract]

Computations of Basic Earnings Per Common Share

The computations of basic earnings per common share follow:

	Year Ended December 31
	2019			2018			2017
	(In thousands, except per share)
Income available to common shareholders:
Net income	$	1,929,149		$	1,918,080		$	1,408,306
Less: Preferred stock dividends(a)		(69,441	)		(72,521	)		(72,734	)
Net income available to common equity		1,859,708			1,845,559			1,335,572
Less: Income attributable to unvested stock-based compensation awards		(10,199	)		(9,531	)		(8,069	)
Net income available to common shareholders	$	1,849,509		$	1,836,028		$	1,327,503
Weighted-average shares outstanding:
Common shares outstanding (including common stock issuable) and unvested stock-based compensation awards		135,169			144,740			153,092
Less: Unvested stock-based compensation awards		(741	)		(748	)		(933	)
Weighted-average shares outstanding		134,428			143,992			152,159

Basic earnings per common share	$	13.76		$	12.75		$	8.72

(a)	Including impact of not as yet declared cumulative dividends.

Computations of Diluted Earnings Per Common Share

The computations of diluted earnings per common share follow:

	Year Ended December 31
	2019			2018			2017
	(In thousands, except per share)

Net income available to common equity	$	1,859,708		$	1,845,559		$	1,335,572
Less: Income attributable to unvested stock-based compensation awards		(10,197	)		(9,524	)		(8,055	)
Net income available to common shareholders	$	1,849,511		$	1,836,035		$	1,327,517
Adjusted weighted-average shares outstanding:
Common and unvested stock-based compensation awards		135,169			144,740			153,092
Less: Unvested stock-based compensation awards		(741	)		(748	)		(933	)
Plus: Incremental shares from assumed conversion of stock-based compensation awards and warrants to purchase common stock		34			159			392
Adjusted weighted-average shares outstanding		134,462			144,151			152,551

Diluted earnings per common share	$	13.75		$	12.74		$	8.70

Comprehensive income (Tables)

12 Months Ended

Dec. 31, 2019

Equity [Abstract]

Impact of Reclassification from AOCI to Retained Earnings

The impact of that reclassification was an increase in retained earnings as of December 31, 2017 resulting from items remaining in AOCI as of that date as follows:

	(In thousands)

Net unrealized losses on investment securities	$	8,065
Defined benefit plans liability adjustments		53,960
Cash flow hedges and other		2,004
Increase to retained earnings	$	64,029

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						Total Amount				Income
	Securities (a)			Plans			Other			Before Tax				Tax			Net
	(In thousands)

Balance — January 1, 2019	$	(200,107	)		(354,502	)		(14,719	)	$	(569,328	)			149,247		$	(420,081	)
Other comprehensive income before reclassifications:
Unrealized holding gains, net		247,411			—			—			247,411				(65,009	)		182,402
Foreign currency translation adjustment		—			—			1,381			1,381				(290	)		1,091
Unrealized gains on cash flow hedges		—			—			160,373			160,373				(42,163	)		118,210
Current year benefit plans losses		—			(126,618	)		—			(126,618	)			33,287			(93,331	)
Total other comprehensive income (loss) before reclassifications		247,411			(126,618	)		161,754			282,547				(74,175	)		208,372
Amounts reclassified from accumulated other comprehensive income that (increase) decrease net income:
Amortization of unrealized holding losses on held-to-maturity (“HTM”) securities		3,394			—			—			3,394		(c)		(892	)		2,502
Losses realized in net income		3			—			—			3		(d)		(1	)		2
Accretion of net gain on terminated cash flow hedges		—			—			(136	)		(136	)	(e)		36			(100	)
Net yield adjustment from cash flow hedges currently in effect		—			—			(13,011	)		(13,011	)	(c)		3,421			(9,590	)
Amortization of prior service credit		—			(4,173	)		—			(4,173	)	(f)		1,097			(3,076	)
Amortization of actuarial losses		—			20,745			—			20,745		(f)		(5,454	)		15,291
Total other comprehensive income (loss)		250,808			(110,046	)		148,607			289,369				(75,968	)		213,401
Balance — December 31, 2019	$	50,701			(464,548	)		133,888		$	(279,959	)			73,279		$	(206,680	)

Balance — January 1, 2018	$	(59,957	)		(413,168	)		(20,165	)	$	(493,290	)			129,476		$	(363,814	)
Cumulative effect of change in accounting principle — equity securities (a)		(22,795	)		—			—			(22,795	)			5,942			(16,853	)
Other comprehensive income before reclassifications:
Unrealized holding losses, net		(121,589	)		—			—			(121,589	)			31,946			(89,643	)
Foreign currency translation adjustment		—			—			(2,817	)		(2,817	)			592			(2,225	)
Unrealized losses on cash flow hedges		—			—			(4,965	)		(4,965	)			1,306			(3,659	)
Current year benefit plans gains		—			19,871			—			19,871				(5,224	)		14,647
Total other comprehensive income (loss) before reclassifications		(121,589	)		19,871			(7,782	)		(109,500	)			28,620			(80,880	)
Amounts reclassified from accumulated other comprehensive income that (increase) decrease net income:
Amortization of unrealized holding losses on HTM securities		4,252			—			—			4,252		(c)		(1,118	)		3,134
Gains realized in net income		(18	)		—			—			(18	)	(d)		4			(14	)
Accretion of net gain on terminated cash flow hedges		—			—			(111	)		(111	)	(e)		29			(82	)
Net yield adjustment from cash flow hedges currently in effect		—			—			13,339			13,339		(c)		(3,507	)		9,832
Amortization of prior service credit		—			(4,172	)		—			(4,172	)	(f)		1,097			(3,075	)
Amortization of actuarial losses		—			42,967			—			42,967		(f)		(11,296	)		31,671
Total other comprehensive income (loss)		(117,355	)		58,666			5,446			(53,243	)			13,829			(39,414	)
Balance — December 31, 2018	$	(200,107	)		(354,502	)		(14,719	)	$	(569,328	)			149,247		$	(420,081	)

							Defined						Total
	Investment Securities						Benefit						Amount				Income
	With OTTI (b)			All Other			Plans			Other			Before Tax				Tax			Net
	(In thousands)

Balance — January 1, 2017	$	46,725			(73,785	)		(449,917	)		(8,268	)	$	(485,245	)			190,609		$	(294,636	)
Other comprehensive income before reclassifications:
Unrealized holding losses, net		(8,746	)		(6,259	)		—			—			(15,005	)			7,269			(7,736	)
Foreign currency translation adjustment		—			—			—			4,447			4,447				(2,206	)		2,241
Unrealized losses on cash flow hedges		—			—			—			(12,291	)		(12,291	)			4,837			(7,454	)
Current year benefit plans gains		—			—			9,276			—			9,276				(3,650	)		5,626
Total other comprehensive income (loss) before reclassifications		(8,746	)		(6,259	)		9,276			(7,844	)		(13,573	)			6,250			(7,323	)
Amounts reclassified from accumulated other comprehensive income that (increase) decrease net income:
Amortization of unrealized holding losses on HTM securities		—			3,387			—			—			3,387		(c)		(1,333	)		2,054
Gains realized in net income		(18,351	)		(2,928	)		—			—			(21,279	)	(d)		7,195			(14,084	)
Accretion of net gain on terminated cash flow hedges		—			—			—			(137	)		(137	)	(e)		54			(83	)
Net yield adjustment from cash flow hedges currently in effect		—			—			—			(3,916	)		(3,916	)	(c)		1,541			(2,375	)
Amortization of prior service credit		—			—			(802	)		—			(802	)	(f)		315			(487	)
Amortization of actuarial losses		—			—			28,275			—			28,275		(f)		(11,126	)		17,149
Total other comprehensive income (loss)		(27,097	)		(5,800	)		36,749			(11,897	)		(8,045	)			2,896			(5,149	)
Reclassification of income tax effects to retained earnings		—			—			—			—			—				(64,029	)		(64,029	)
Balance — December 31, 2017	$	19,628			(79,585	)		(413,168	)		(20,165	)	$	(493,290	)			129,476		$	(363,814	)

(b) Other-than-temporary impairment.

(d) Included in gain (loss) on bank investment securities.

(e) Included in interest expense.

(f) Included in other costs of operations.

Accumulated Other Comprehensive Income (Loss), Net

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

				Defined
	Investment Securities			Benefit Plans			Other			Total
	(In thousands)

Balance at January 1, 2017	$	(16,319	)	$	(272,874	)	$	(5,443	)	$	(294,636	)
Net gain (loss) during 2017		(19,766	)		22,288			(7,671	)		(5,149	)
Reclassification of income tax effects to retained earnings		(8,065	)		(53,960	)		(2,004	)		(64,029	)
Balance at December 31, 2017		(44,150	)		(304,546	)		(15,118	)		(363,814	)
Cumulative effect of change in accounting principle — equity securities		(16,853	)		—			—			(16,853	)
Net gain (loss) during 2018		(86,523	)		43,243			3,866			(39,414	)
Balance at December 31, 2018		(147,526	)		(261,303	)		(11,252	)		(420,081	)
Net gain (loss) during 2019		184,906			(81,116	)		109,611			213,401
Balance at December 31, 2019	$	37,380		$	(342,419	)	$	98,359		$	(206,680	)

Other income and other expense (Tables)

12 Months Ended

Dec. 31, 2019

Other Income And Expenses [Abstract]

Other Income and Other Expense

	Year Ended December 31
	2019		2018		2017
	(In thousands)
Other income:
Credit-related fee income	$	86,792	$	82,614	$	77,580
Other expense:
Professional services		330,900		312,998		289,862
Accrual for Wilmington Trust Corporation legal-related matters				135,000
Amortization of capitalized mortgage servicing rights		71,888

Derivative financial instruments (Tables)

12 Months Ended

Dec. 31, 2019

Derivative Instruments And Hedging Activities Disclosure [Abstract]

Information about Interest Rate Swap Agreements

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


					Weighted-						Estimated
	Notional		Average		Average Rate						Fair Value
	Amount		Maturity		Fixed			Variable			Gain (Loss) (a)
	(In thousands)		(In years)								(In thousands)
December 31, 2019
Fair value hedges:
Fixed rate long-term borrowings (b)	$	3,800,000		2.2		2.51	%		2.27	%	$	(567	)
Cash flow hedges:
Interest payments on variable rate commercial real estate loans (b)(c)		53,750,000		1.4		2.44	%		1.73	%		(1,195	)
Total	$	57,550,000		1.5							$	(1,762	)
December 31, 2018
Fair value hedges:
Fixed rate long-term borrowings (b)	$	4,450,000		2.8		2.47	%		3.02	%	$	4,219
Cash flow hedges:
Interest payments on variable rate commercial real estate loans (b)(d)		15,400,000		1.3		1.52	%		2.35	%		1,311
Total	$	19,850,000		1.7							$	5,530

(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 $40.4 billion of forward-starting interest rate swap agreements that will become effective in 2020-2022.

(d)	Includes notional amount and terms of $12.6 billion of forward-starting interest rate swap agreements.

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, 2019 mature as follows:

	(In thousands)
Year ending December 31:
2020	$	12,200,000
2021		28,350,000
2022		16,000,000
2023		500,000
2027		500,000
	$	57,550,000

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
	2019		2018		2019		2018
	(In thousands)
Derivatives designated and qualifying as hedging instruments
Interest rate swap agreements (a)	$	232	$	5,530	$	1,994	$	—
Commitments to sell real estate loans (a)		1,195		1,090		421		6,434
		1,427		6,620		2,415		6,434
Derivatives not designated and qualifying as hedging instruments
Mortgage-related commitments to originate real estate loans for sale (a)		11,965		9,304		1,225		1,592
Commitments to sell real estate loans (a)		3,074		3,702		3,548		4,535
Trading:
Interest rate contracts (b)		398,295		118,687		68,103		169,255
Foreign exchange and other option and futures contracts (b)		12,506		10,549		11,800		8,870
		425,840		142,242		84,676		184,252
Total derivatives	$	427,267	$	148,862	$	87,091	$	190,686

(a)	Asset derivatives are reported in other assets and liability derivatives are reported in other liabilities.

(b)

	Carrying Amount of the Hedged Item				Cumulative Amount of Fair Value Hedging Adjustment Increasing (Decreasing) the Carrying Amount of the Hedged Item
	December 31				December 31
	2019		2018		2019		2018
	(In thousands)
Location in the Consolidated Balance Sheet of the Hedged Items in Fair Value Hedges

Long-term debt	$	3,840,775	$	4,394,109	$	43,640	$	(51,102	)

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

	Amount of Gain (Loss) Recognized
	Year Ended December 31, 2019					Year Ended December 31, 2018					Year Ended December 31, 2017
	Derivative		Hedged Item			Derivative			Hedged Item		Derivative			Hedged Item
	(In thousands)
Derivatives in fair value hedging relationships
Interest rate swap agreements:
Fixed rate long-term borrowings (a)	$	95,006		(94,742	)	$	(10,006	)		10,969	$	(52,392	)		51,628
Derivatives not designated as hedging instruments
Trading:
Interest rate contracts (b)	$	24,701				$	4,506				$	5,398
Foreign exchange and other option and futures contracts (b)		8,511					9,416					6,821
Total	$	33,212				$	13,922				$	12,219

(a)	Effective January 1, 2018, reported as an adjustment to interest expense. Prior to 2018, reported as other revenues from operations.

(b)	Reported as trading account and foreign exchange gains.

Fair value measurements (Tables)

12 Months Ended

Dec. 31, 2019

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, 2019 and 2018 measured at estimated fair value on a recurring basis:

	Fair Value Measurements		Level 1 (a)		Level 2 (a)		Level 3
	(In thousands)
December 31, 2019
Trading account assets	$	470,129	$	49,040	$	421,089	$	—
Investment securities available for sale:
U.S. Treasury and federal agencies		9,767		—		9,767		—
Obligations of states and political subdivisions		775		—		775		—
Mortgage-backed securities:
Government issued or guaranteed		6,180,940		—		6,180,940		—
Privately issued		16		—		—		16
Other debt securities		127,278		—		127,278		—
		6,318,776		—		6,318,760		16
Equity securities		140,041		100,637		39,404		—
Real estate loans held for sale		442,079		—		442,079		—
Other assets (b)		16,466		—		4,501		11,965
Total assets	$	7,387,491	$	149,677	$	7,225,833	$	11,981
Trading account liabilities	$	79,903	$	—	$	79,903	$	—
Other liabilities (b)		7,188		—		5,963		1,225
Total liabilities	$	87,091	$	—	$	85,866	$	1,225

December 31, 2018
Trading account assets	$	185,584	$	46,018	$	139,566	$	—
Investment securities available for sale:
U.S. Treasury and federal agencies		1,336,931		—		1,336,931		—
Obligations of states and political subdivisions		1,659		—		1,659		—
Mortgage-backed securities:
Government issued or guaranteed		7,216,991		—		7,216,991		—
Privately issued		22		—		—		22
Other debt securities		126,906		—		126,906		—
		8,682,509		—		8,682,487		22
Equity securities		93,917		71,989		21,928		—
Real estate loans held for sale		551,697		—		551,697		—
Other assets (b)		19,626		—		10,322		9,304
Total assets	$	9,533,333	$	118,007	$	9,406,000	$	9,326
Trading account liabilities	$	178,125	$	—	$	178,125	$	—
Other liabilities (b)		12,561		—		10,969		1,592
Total liabilities	$	190,686	$	—	$	189,094	$	1,592

(a)	There were no significant transfers between Level 1 and Level 2 of the fair value hierarchy during the years ended December 31, 2019 and 2018.

(b)	Comprised predominantly of interest rate swap agreements used for interest rate risk management (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, 2019, 2018 and 2017 were as follows:

	Investment Securities Available for Sale
	Privately Issued Mortgage-Backed Securities			Other Assets and Other Liabilities
	(In thousands)
2019
Balance — January 1, 2019	$	22		$	7,712
Total gains realized/unrealized:
Included in earnings		—			129,398		(b)
Settlements		(6	)		—
Transfers out of Level 3 (a)		—			(126,370	)	(c)
Balance — December 31, 2019	$	16			10,740
Changes in unrealized gains included in earnings related to assets still held at December 31, 2019	$	—			11,146		(b)

2018
Balance — January 1, 2018	$	28			8,303
Total gains realized/unrealized:
Included in earnings		—			58,740		(b)
Settlements		(6	)		—
Transfers out of Level 3 (a)		—			(59,331	)	(c)
Balance — December 31, 2018	$	22			7,712
Changes in unrealized gains included in earnings related to assets still held at December 31, 2018	$	—			7,386		(b)

2017
Balance — January 1, 2017	$	44			7,325
Total gains realized/unrealized:
Included in earnings		—			77,832		(b)
Settlements		(16	)		—
Transfers out of Level 3 (a)		—			(76,854	)	(c)
Balance — December 31, 2017	$	28			8,303
Changes in unrealized gains included in earnings related to assets still held at December 31, 2017	$	—			7,978		(b)

(a)	The Company’s policy for transfers between fair value levels is to recognize the transfer as of the actual date of the event or change in circumstances that caused the transfer.

(b)	Reported as mortgage banking revenues in the consolidated statement of income and includes the fair value of commitment issuances and expirations.

(c)	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, 2019 and 2018:

Fair Value

Valuation

Technique

Unobservable

Inputs/Assumptions

Range

(Weighted-

Average)

(In thousands)

December 31, 2019

Recurring fair value

measurements

Privately issued mortgage-

backed securities

Two independent pricing quotes

—

Net other assets (liabilities) (a)

10,740

Discounted cash flow

Commitment expirations

0%-99% (13%)

December 31, 2018

Recurring fair value

measurements

Privately issued mortgage-

backed securities

Two independent pricing quotes

—

Net other assets (liabilities) (a)

7,712

Discounted cash flow

Commitment expirations

0%-95% (13%)

(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, 2019
	Carrying Amount			Estimated Fair Value			Level 1		Level 2			Level 3
	(In thousands)
Financial assets:
Cash and cash equivalents	$	1,432,805			1,432,805			1,394,984		37,821			—
Interest-bearing deposits at banks		7,190,154			7,190,154			—		7,190,154			—
Federal funds sold		3,500			3,500			—		3,500			—
Trading account assets		470,129			470,129			49,040		421,089			—
Investment securities		9,497,251			9,539,540			100,637		9,351,793			87,110
Loans and leases:
Commercial loans and leases		23,838,168			23,510,908			—		—			23,510,908
Commercial real estate loans		35,541,914			35,517,180			—		28,338			35,488,842
Residential real estate loans		16,156,094			16,227,274			—		3,990,848			12,236,426
Consumer loans		15,386,693			15,413,262			—		—			15,413,262
Allowance for credit losses		(1,051,071	)		—			—		—			—
Loans and leases, net		89,871,798			90,668,624			—		4,019,186			86,649,438
Accrued interest receivable		333,142			333,142			—		333,142			—
Financial liabilities:
Noninterest-bearing deposits	$	(32,396,407	)		(32,396,407	)		—		(32,396,407	)		—
Savings and interest-checking deposits		(54,932,162	)		(54,932,162	)		—		(54,932,162	)		—
Time deposits		(5,757,456	)		(5,829,347	)		—		(5,829,347	)		—
Deposits at Cayman Islands office		(1,684,044	)		(1,684,044	)		—		(1,684,044	)		—
Short-term borrowings		(62,363	)		(62,363	)		—		(62,363	)		—
Long-term borrowings		(6,986,186	)		(7,063,165	)		—		(7,063,165	)		—
Accrued interest payable		(105,374	)		(105,374	)		—		(105,374	)		—
Trading account liabilities		(79,903	)		(79,903	)		—		(79,903	)		—
Other financial instruments:
Commitments to originate real estate loans for sale	$	10,740			10,740			—		—			10,740
Commitments to sell real estate loans		300			300			—		300			—
Other credit-related commitments		(136,470	)		(136,470	)		—		—			(136,470	)
Interest rate swap agreements used for interest rate risk management		(1,762	)		(1,762	)		—		(1,762	)		—

	December 31, 2018
	Carrying Amount			Estimated Fair Value			Level 1		Level 2			Level 3
				(In thousands)
Financial assets:
Cash and cash equivalents	$	1,605,439			1,605,439			1,528,302		77,137			—
Interest-bearing deposits at banks		8,105,197			8,105,197			—		8,105,197			—
Trading account assets		185,584			185,584			46,018		139,566			—
Investment securities		12,692,813			12,631,656			71,989		12,456,467			103,200
Loans and leases:
Commercial loans and leases		22,977,976			22,587,387			—		—			22,587,387
Commercial real estate loans		34,363,556			33,832,558			—		346,775			33,485,783
Residential real estate loans		17,154,446			16,974,545			—		3,920,447			13,054,098
Consumer loans		13,970,499			13,819,545			—		—			13,819,545
Allowance for credit losses		(1,019,444	)		—			—		—			—
Loans and leases, net		87,447,033			87,214,035			—		4,267,222			82,946,813
Accrued interest receivable		353,965			353,965			—		353,965			—
Financial liabilities:
Noninterest-bearing deposits	$	(32,256,668	)		(32,256,668	)		—		(32,256,668	)		—
Savings and interest-checking deposits		(50,963,744	)		(50,963,744	)		—		(50,963,744	)		—
Time deposits		(6,124,254	)		(6,201,957	)		—		(6,201,957	)		—
Deposits at Cayman Islands office		(811,906	)		(811,906	)		—		(811,906	)		—
Short-term borrowings		(4,398,378	)		(4,398,378	)		—		(4,398,378	)		—
Long-term borrowings		(8,444,914	)		(8,385,289	)		—		(8,385,289	)		—
Accrued interest payable		(95,274	)		(95,274	)		—		(95,274	)		—
Trading account liabilities		(178,125	)		(178,125	)		—		(178,125	)		—
Other financial instruments:
Commitments to originate real estate loans for sale	$	7,712			7,712			—		—			7,712
Commitments to sell real estate loans		(6,177	)		(6,177	)		—		(6,177	)		—
Other credit-related commitments		(131,688	)		(131,688	)		—		—			(131,688	)
Interest rate swap agreements used for interest rate risk management		5,530			5,530			—		5,530			—

Commitments and contingencies (Tables)

12 Months Ended

Dec. 31, 2019

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
	2019		2018
	(In thousands)
Commitments to extend credit
Home equity lines of credit	$	5,442,160		5,484,197
Commercial real estate loans to be sold		164,076		229,401
Other commercial real estate		9,029,608		7,556,722
Residential real estate loans to be sold		423,056		245,211
Other residential real estate		448,375		219,351
Commercial and other		16,170,731		14,363,803
Standby letters of credit		2,441,432		2,326,991
Commercial letters of credit		41,059		55,808
Financial guarantees and indemnification contracts		4,108,572		3,529,136
Commitments to sell real estate loans		906,037		940,692

Segment information (Tables)

12 Months Ended

Dec. 31, 2019

Segment Reporting [Abstract]

Information about Company's Segments

Information about the Company’s segments is presented in the accompanying table. Income statement amounts are in thousands of dollars. Balance sheet amounts are in millions of dollars.

	For the Years Ended December 31, 2019, 2018 and 2017
	Business Banking							Commercial Banking						Commercial Real Estate									Discretionary Portfolio
	2019		2018			2017		2019		2018		2017		2019			2018			2017			2019		2018			2017
Net interest income(a)	$	451,307	$	434,579		$	393,948	$	828,888	$	821,812	$	809,301	$	692,526		$	665,220		$	649,378		$	209,807	$	228,051		$	277,095
Noninterest income		113,855		111,600			112,512		289,558		288,908		283,447		214,970			183,955			169,966			26,919		(9,690	)		23,851
		565,162		546,179			506,460		1,118,446		1,110,720		1,092,748		907,496			849,175			819,344			236,726		218,361			300,946
Provision for credit losses		16,501		10,916			15,598		25,580		8,976		11,876		1,537			3,159			(7,524	)		3,608		6,683			31,119
Amortization of core deposit and other intangible assets		—		—			—		—		—		—		1,060			1,060			1,060			—		—			—
Depreciation and other amortization		412		382			393		554		496		509		25,560			25,852			24,410			263		187			279
Other noninterest expense		319,136		305,340			294,493		384,013		364,102		339,936		240,736			217,387			207,493			52,901		65,393			76,021
Income (loss) before taxes		229,113		229,541			195,976		708,299		737,146		740,427		638,603			601,717			593,905			179,954		146,098			193,527
Income tax expense (benefit)		60,617		61,279			80,043		187,835		198,229		303,556		152,977			148,807			229,770			36,342		29,872			58,559
Net income (loss)	$	168,496	$	168,262		$	115,933	$	520,464	$	538,917	$	436,871	$	485,626		$	452,910		$	364,135		$	143,612	$	116,226		$	134,968
Average total assets (in millions)	$	5,793	$	5,631		$	5,602	$	28,142	$	26,626	$	26,573	$	23,921		$	22,885		$	22,741		$	29,081	$	32,123		$	37,203
Capital expenditures (in millions)	$	1	$	—		$	—	$	2	$	—	$	—	$	—		$	—		$	1		$	—	$	1		$	—

	For the Years Ended December 31, 2019, 2018 and 2017
	Residential Mortgage Banking							Retail Banking						All Other									Total
	2019		2018			2017		2019		2018		2017		2019			2018			2017			2019		2018			2017
Net interest income(a)	$	20,008	$	13,933		$	30,328	$	1,389,788	$	1,351,165	$	1,210,066	$	537,940		$	557,542		$	410,928		$	4,130,264	$	4,072,302		$	3,781,044
Noninterest income		393,372		305,560			321,589		327,562		324,228		329,833		695,443			651,439			609,945			2,061,679		1,856,000			1,851,143
		413,380		319,493			351,917		1,717,350		1,675,393		1,539,899		1,233,383			1,208,981			1,020,873			6,191,943		5,928,302			5,632,187
Provision for credit losses		382		(2,178	)		1,254		122,135		112,572		107,412		6,257			(8,128	)		8,265			176,000		132,000			168,000
Amortization of core deposit and other intangible assets		—		—			—		—		—		—		18,430			23,462			30,306			19,490		24,522			31,366
Depreciation and other amortization		46,901		24,288			32,011		38,394		35,274		38,234		68,840			68,004			69,923			180,924		154,483			165,759
Other noninterest expense		274,414		241,624			247,639		839,636		789,783		758,153		1,157,432			1,125,428			1,019,465			3,268,268		3,109,057			2,943,200
Income (loss) before taxes		91,683		55,759			71,013		717,185		737,764		636,100		(17,576	)		215			(107,086	)		2,547,261		2,508,240			2,323,862
Income tax expense (benefit)		19,355		10,272			25,446		189,611		196,467		258,934		(28,625	)		(54,766	)		(40,752	)		618,112		590,160			915,556
Net income (loss)	$	72,328	$	45,487		$	45,567	$	527,574	$	541,297	$	377,166	$	11,049		$	54,981		$	(66,334	)	$	1,929,149	$	1,918,080		$	1,408,306
Average total assets (in millions)	$	2,611	$	2,161		$	2,355	$	15,083	$	13,656	$	12,702	$	14,953		$	13,877		$	13,684		$	119,584	$	116,959		$	120,860
Capital expenditures (in millions)	$	1	$	1		$	—	$	76	$	31	$	34	$	98		$	65		$	44		$	178	$	98		$	79

(a)

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
	2019			2018			2017
	(In thousands)

Revenues	$	(48,559	)	$	(41,285	)	$	(43,941	)
Expenses		(18,218	)		(24,660	)		(32,623	)
Income taxes (benefit)		(7,976	)		(4,371	)		(4,606	)
Net income (loss)		(22,365	)		(12,254	)		(6,712	)

Regulatory matters (Tables)

12 Months Ended

Dec. 31, 2019

Banking And Thrift [Abstract]

Summary of Required Minimum and Well Capitalized Capital Ratios

Pursuant to the rules in effect as of December 31, 2019, the required minimum and well capitalized capital ratios are as follows:

				Well
	Minimum			Capitalized
● Common equity Tier 1 ("CET1") to risk-weighted assets		4.5	%		6.5	%
● Tier 1 capital to risk-weighted assets		6.0	%		8.0	%
● Total capital to risk-weighted assets		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, 2019 and 2018 are presented below:

	M&T (Consolidated)			M&T Bank			Wilmington Trust, N.A.
	(Dollars in thousands)
December 31, 2019:
Common equity Tier 1 capital
Amount	$	10,053,887		$	10,649,953		$	606,538
Ratio(a)		9.73	%		10.34	%		56.35	%
Tier 1 capital
Amount		11,303,836			10,649,953			606,538
Ratio(a)		10.94	%		10.34	%		56.35	%
Total capital
Amount		13,480,612			12,342,834			608,130
Ratio(a)		13.05	%		11.99	%		56.50	%
Leverage
Amount		11,303,836			10,649,953			606,538
Ratio(b)		9.59	%		9.08	%		13.12	%
December 31, 2018:
Common equity Tier 1 capital
Amount	$	9,960,811		$	10,636,136		$	585,767
Ratio(a)		10.13	%		10.84	%		60.69	%
Tier 1 capital
Amount		11,193,770			10,636,136			585,767
Ratio(a)		11.38	%		10.84	%		60.69	%
Total capital
Amount		13,454,137			12,475,296			589,671
Ratio(a)		13.68	%		12.72	%		61.10	%
Leverage
Amount		11,193,770			10,636,136			585,767
Ratio(b)		9.88	%		9.42	%		12.51	%

(a)	The ratio of capital to risk-weighted assets, as defined by regulation.

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

Parent company financial statements (Tables)

12 Months Ended

Dec. 31, 2019

Condensed Financial Information Of Parent Company Only Disclosure [Abstract]

Condensed Balance Sheet

	December 31
	2019		2018
	(In thousands)
Assets
Cash in subsidiary bank	$	83,531	$	40,609
Due from consolidated bank subsidiaries
Money-market savings		876,819		856,881
Current income tax receivable		1,261		1,117
Total due from consolidated bank subsidiaries		878,080		857,998
Investments in consolidated subsidiaries
Banks		15,732,008		15,491,277
Other		301,765		324,360
Investments in trust preferred entities (note 19)		23,022		23,241
Other assets		67,732		64,187
Total assets	$	17,086,138	$	16,801,672
Liabilities
Accrued expenses and other liabilities	$	74,235	$	63,719
Long-term borrowings		1,295,254		1,277,762
Total liabilities		1,369,489		1,341,481
Shareholders’ equity		15,716,649		15,460,191
Total liabilities and shareholders’ equity	$	17,086,138	$	16,801,672

Condensed Statement of Income

	Year Ended December 31
	2019			2018			2017
	(In thousands, except per share)
Income
Dividends from consolidated bank subsidiaries	$	2,025,000		$	1,250,000		$	1,540,000
Equity in earnings of Bayview Lending Group LLC		36,740			23,500			352
Other income		7,216			2,417			9,493
Total income		2,068,956			1,275,917			1,549,845
Expense
Interest on long-term borrowings		51,938			36,354			21,591
Other expense		25,236			23,894			19,636
Total expense		77,174			60,248			41,227
Income before income taxes and equity in undistributed income of subsidiaries		1,991,782			1,215,669			1,508,618
Income tax credits		8,313			8,446			26,453
Income before equity in undistributed income of subsidiaries		2,000,095			1,224,115			1,535,071
Equity in undistributed income of subsidiaries
Net income of subsidiaries		1,954,054			1,943,965			1,413,235
Less: dividends received		(2,025,000	)		(1,250,000	)		(1,540,000	)
Equity in undistributed income of subsidiaries		(70,946	)		693,965			(126,765	)
Net income	$	1,929,149		$	1,918,080		$	1,408,306
Net income per common share
Basic	$	13.76		$	12.75		$	8.72
Diluted		13.75			12.74			8.70

Condensed Statement of Cash Flow

Condensed Statement of Cash Flows

	Year Ended December 31
	2019			2018			2017
	(In thousands)
Cash flows from operating activities
Net income	$	1,929,149		$	1,918,080		$	1,408,306
Adjustments to reconcile net income to net cash provided by operating activities
Equity in undistributed income of subsidiaries		70,946			(693,965	)		126,765
Provision for deferred income taxes		5,263			4,949			4,543
Net change in accrued income and expense		(34,525	)		(8,242	)		(170	)
Gain on sale of assets		—			—			(2,995	)
Net cash provided by operating activities		1,970,833			1,220,822			1,536,449
Cash flows from investing activities
Proceeds from sales or maturities of investment securities		100			—			—
Other, net		51,235			29,933			12,407
Net cash provided by investing activities		51,335			29,933			12,407
Cash flows from financing activities
Purchases of treasury stock		(1,349,785	)		(2,194,396	)		(1,205,905	)
Dividends paid — common		(552,138	)		(510,382	)		(457,402	)
Dividends paid — preferred		(67,454	)		(72,521	)		(72,734	)
Proceeds from long-term borrowings		—			748,595			—
Redemption of Series A and Series C preferred stock		(381,500	)		—			—
Proceeds from issuance of Series G preferred stock		396,000			—			—
Other, net		(4,431	)		45,913			34,524
Net cash used by financing activities		(1,959,308	)		(1,982,791	)		(1,701,517	)
Net increase (decrease) in cash and cash equivalents		62,860			(732,036	)		(152,661	)
Cash and cash equivalents at beginning of year		897,490			1,629,526			1,782,187
Cash and cash equivalents at end of year	$	960,350		$	897,490		$	1,629,526
Supplemental disclosure of cash flow information
Interest received during the year	$	1,752		$	2,219		$	2,313
Interest paid during the year		49,451			17,482			18,498
Income taxes received during the year		6,251			6,362			21,740

Significant Accounting Policies - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2019
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
Maximum [Member]
Significant Accounting Policies [Line Items]
Loans secured by real estate delinquent period threshold for return to accrual status	90 days
Consumer loan delinquent period threshold for consideration for charge off	180 days
Estimated useful lives	10 years
Minimum [Member]
Significant Accounting Policies [Line Items]
Consumer loan delinquent period threshold for consideration for charge off	91 days
Estimated useful lives	5 years
Income tax benefit recognition criteria percentage threshold	50.00%

Investment Securities - Additional Information (Detail)	12 Months Ended
Investment Securities - Additional Information (Detail)	Dec. 31, 2019 USD ($) Investment	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Investment Holdings [Line Items]
Gross realized gains on investment securities			$ 23,000,000
Gross realized gains(loss) on sale of investment securities	$ 0	$ 0	0
Number of investment securities with aggregate gross unrealized losses \| Investment	641
Unrealized losses on individual investment securities	$ 50,000,000
Cost method investment securities	382,000,000
Investment securities pledged to secure debt carrying value	1,900,000,000
Pledged securities that can be sold or repledged	200,339,000	$ 487,365,000
Available-for-Sale Securities [Member]
Investment Holdings [Line Items]
Investment securities pledged to secure debt carrying value	$ 1,500,000,000
Government Agency [Member]
Investment Holdings [Line Items]
Number of investment securities that exceeded ten percent of shareholders' equity \| Investment	0
Non-U.S. Government [Member]
Investment Holdings [Line Items]
Number of investment securities that exceeded ten percent of shareholders' equity \| Investment	0
Government Issued or Guaranteed [Member]
Investment Holdings [Line Items]
Number of investment securities that exceeded ten percent of shareholders' equity \| Investment	0
Collateralized Debt Obligations [Member] \| Fannie Mae And Freddie Mac Preferred Stock
Investment Holdings [Line Items]
Net gain on securities sold			$ 18,000,000
Retained Earnings [Member] \| Adjustments for New Accounting Pronouncement [Member]
Investment Holdings [Line Items]
Reclassification from accumulated comprehensive income to retained earnings, net of tax	$ 17,000,000

Investment Securities - Amortized Cost and Estimated Fair Value of Investment Securities (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Schedule Of Amortized Cost And Estimated Fair Value Of Investment Securities [Line Items]
Investment securities available for sale, amortized cost	$ 6,258,276	$ 8,869,423
Investment securities available for sale, gross unrealized gains	90,723	16,528
Investment securities available for sale, gross unrealized losses	30,223	203,442
Investment securities available for sale, estimated fair value	6,318,776	8,682,509
Amortized cost for held to maturity	2,656,917	3,316,640
Gross unrealized gains for held to maturity	62,462	16,532
Gross unrealized losses for held to maturity	20,173	77,689
Estimated fair value for held to maturity	2,699,206	3,255,483
Equity and other securities, Amortized Cost	487,041	677,187
Equity securities, Gross Unrealized Gains	34,786	17,295
Equity securities, Gross Unrealized Losses	269	818
Equity and other securities, Estimated Fair Value	521,558	693,664
Other securities, Amortized cost	381,517	599,747
Other securities, Estimated fair value	381,517	599,747
Total debt securities Amortized cost	8,915,193	12,186,063
Total debt securities Gross unrealized gains	153,185	33,060
Total debt securities Gross unrealized losses	50,396	281,131
Total debt securities Estimated fair value	9,017,982	11,937,992
Readily marketable securities Amortized cost	105,524	77,440
Readily marketable securities Gross unrealized gains	34,786	17,295
Readily marketable securities Gross unrealized losses	269	818
Readily marketable securities Estimated fair value	140,041	93,917
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	9,742	1,346,782
Investment securities available for sale, gross unrealized gains	41
Investment securities available for sale, gross unrealized losses	16	9,851
Investment securities available for sale, estimated fair value	9,767	1,336,931
Amortized cost for held to maturity	249,862	446,542
Gross unrealized gains for held to maturity	286
Gross unrealized losses for held to maturity		239
Estimated fair value for held to maturity	250,148	446,303
Obligations of States and Political Subdivisions [Member]
Schedule Of Amortized Cost And Estimated Fair Value Of Investment Securities [Line Items]
Investment securities available for sale, amortized cost	776	1,660
Investment securities available for sale, gross unrealized gains	2	4
Investment securities available for sale, gross unrealized losses	3	5
Investment securities available for sale, estimated fair value	775	1,659
Amortized cost for held to maturity	4,140	7,494
Gross unrealized gains for held to maturity	16	22
Gross unrealized losses for held to maturity		12
Estimated fair value for held to maturity	4,156	7,504
Government Issued or Guaranteed [Member]
Schedule Of Amortized Cost And Estimated Fair Value Of Investment Securities [Line Items]
Investment securities available for sale, amortized cost	6,113,913	7,383,340
Investment securities available for sale, gross unrealized gains	88,634	15,754
Investment securities available for sale, gross unrealized losses	21,607	182,103
Investment securities available for sale, estimated fair value	6,180,940	7,216,991
Amortized cost for held to maturity	2,306,180	2,745,776
Gross unrealized gains for held to maturity	50,381	4,165
Gross unrealized losses for held to maturity	1,992	55,111
Estimated fair value for held to maturity	2,354,569	2,694,830
Privately Issued [Member]
Schedule Of Amortized Cost And Estimated Fair Value Of Investment Securities [Line Items]
Investment securities available for sale, amortized cost	16	24
Investment securities available for sale, gross unrealized losses		2
Investment securities available for sale, estimated fair value	16	22
Amortized cost for held to maturity	93,496	113,160
Gross unrealized gains for held to maturity	11,779	12,345
Gross unrealized losses for held to maturity	18,181	22,327
Estimated fair value for held to maturity	87,094	103,178
Other Debt Securities [Member]
Schedule Of Amortized Cost And Estimated Fair Value Of Investment Securities [Line Items]
Investment securities available for sale, amortized cost	133,829	137,617
Investment securities available for sale, gross unrealized gains	2,046	770
Investment securities available for sale, gross unrealized losses	8,597	11,481
Investment securities available for sale, estimated fair value	127,278	126,906
Amortized cost for held to maturity	3,239	3,668
Estimated fair value for held to maturity	$ 3,239	$ 3,668

Investment Securities - Amortized Cost and Estimated Fair Value of Debt Securities by Contractual Maturity (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Debt securities available for sale:
Due in one year or less	$ 4,418
Due after one year through five years	10,717
Due after five years through ten years	99,212
Due after ten years	30,000
Total available for sale (amortized cost)	144,347
Mortgage-backed securities available for sale	6,113,929
Investment securities available for sale, amortized cost	6,258,276	$ 8,869,423
Debt securities held to maturity:
Due in one year or less	251,457
Due after one year through five years	2,545
Due after ten years	3,239
Total available for held to maturity (amortized cost)	257,241
Mortgage-backed securities held to maturity	2,399,676
Amortized cost for held to maturity	2,656,917	3,316,640
Debt securities available for sale:
Due in one year or less	4,427
Due after one year through five years	10,777
Due after five years through ten years	98,616
Due after ten years	24,000
Total available for sale (fair value)	137,820
Mortgage-backed securities available for sale	6,180,956
Total	6,318,776	8,682,509
Debt securities held to maturity:
Due in one year or less	251,749
Due after one year through five years	2,555
Due after ten years	3,239
Total available for held to maturity (fair value)	257,543
Mortgage-backed securities held to maturity	2,441,663
Total	$ 2,699,206	$ 3,255,483

Investment Securities - Investment Securities in Continuous Unrealized Loss Position (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Estimated fair value, Less than 12 months	$ 125,305	$ 459,960
Available For Sale Securities Continuous Unrealized Losses Position Less Than Twelve Months Aggregate Losses	(583)	(5,088)
Estimated fair value, 12 months or more	2,061,847	7,048,346
Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or More Aggregate Losses	(29,640)	(198,354)
Held to maturity, Estimated fair value, Less than 12 months	2,727	625,657
Held To Maturity Securities Continuous Unrealized Loss Position Less Than12 Months Aggregate Losses	(5)	(1,228)
Held to maturity, Estimated fair value, 12 months or more	194,891	2,137,792
Held To Maturity Securities Continuous Unrealized Loss Position12 Months Or Longer Aggregate Losses	(20,168)	(76,461)
Total investment securities, fair value less than 12 months	128,032	1,085,617
Investment Securities Continuous Unrealized Loss Position Less Than Twelve Months Aggregate Losses	(588)	(6,316)
Total of investment securities, fair value, 12 Months or More	2,256,738	9,186,138
Investment Securities Continuous Unrealized Loss Position Twelve Months or Longer Aggregate Losses	(49,808)	(274,815)
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	1,406	273
Available For Sale Securities Continuous Unrealized Losses Position Less Than Twelve Months Aggregate Losses	(7)	(2)
Estimated fair value, 12 months or more	2,893	1,335,559
Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or More Aggregate Losses	(9)	(9,849)
Held to maturity, Estimated fair value, Less than 12 months		446,303
Held To Maturity Securities Continuous Unrealized Loss Position Less Than12 Months Aggregate Losses		(239)
Obligations of States and Political Subdivisions [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Estimated fair value, Less than 12 months		629
Available For Sale Securities Continuous Unrealized Losses Position Less Than Twelve Months Aggregate Losses		(5)
Estimated fair value, 12 months or more	277
Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or More Aggregate Losses	(3)
Held to maturity, Estimated fair value, 12 months or more		3,126
Held To Maturity Securities Continuous Unrealized Loss Position12 Months Or Longer Aggregate Losses		(12)
Government Issued or Guaranteed [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Estimated fair value, Less than 12 months	117,299	405,558
Available For Sale Securities Continuous Unrealized Losses Position Less Than Twelve Months Aggregate Losses	(222)	(2,892)
Estimated fair value, 12 months or more	2,002,364	5,646,773
Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or More Aggregate Losses	(21,385)	(179,211)
Held to maturity, Estimated fair value, Less than 12 months	2,727	179,354
Held To Maturity Securities Continuous Unrealized Loss Position Less Than12 Months Aggregate Losses	(5)	(989)
Held to maturity, Estimated fair value, 12 months or more	145,235	2,082,723
Held To Maturity Securities Continuous Unrealized Loss Position12 Months Or Longer Aggregate Losses	(1,987)	(54,122)
Other Debt Securities [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Estimated fair value, Less than 12 months	6,600	53,478
Available For Sale Securities Continuous Unrealized Losses Position Less Than Twelve Months Aggregate Losses	(354)	(2,187)
Estimated fair value, 12 months or more	56,313	66,014
Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or More Aggregate Losses	(8,243)	(9,294)
Privately Issued [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Estimated fair value, Less than 12 months		22
Available For Sale Securities Continuous Unrealized Losses Position Less Than Twelve Months Aggregate Losses		(2)
Held to maturity, Estimated fair value, 12 months or more	49,656	51,943
Held To Maturity Securities Continuous Unrealized Loss Position12 Months Or Longer Aggregate Losses	$ (18,181)	$ (22,327)

Loans and Leases - Total Loans and Leases Outstanding (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Loans
Total loans	$ 89,776,328	$ 87,326,591
Leases
Total loans and leases	91,188,525	88,733,492
Unearned discount	(265,656)	(267,015)
Loans and leases, net of unearned discount	90,922,869	88,466,477
Commercial Financial Loan [Member]
Loans
Total loans	22,575,700	21,730,012
Residential Real Estate [Member]
Loans
Total loans	16,098,125	17,150,658
Commercial Real Estate [Member]
Loans
Total loans	26,718,325	25,666,200
Construction Real Estate [Member]
Loans
Total loans	9,010,297	8,823,635
Consumer Real Estate [Member]
Loans
Total loans	15,373,881	13,956,086
Commercial Lease [Member]
Loans
Total loans	$ 1,412,197	$ 1,406,901

Loans and Leases - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Loans And Leases Receivable [Line Items]
Charges incurred for reimbursement of loan	$ 0	$ 0	$ 0
Interest income that would have been recognized on nonaccrual and renegotiated loans if those loans were accruing interest at their originally contracted terms	68,000,000	69,000,000	64,000,000
Interest on nonaccrual and renegotiated loans included in interest income	33,000,000	33,000,000	$ 31,000,000
Contractual principal and interest payments	228,000,000	303,000,000
Guaranteed amount included in the estimated residual value of leased assets associated with direct financing leases	37,000,000	39,000,000
Amount of foreclosed residential real estate property held	76,000,000	77,000,000
Loans secured by residential real estate that were in the process of foreclosure	$ 402,000,000	391,000,000
Percentage loans in the process of foreclosure, serviced by other entities, classified as government guaranteed	36.00%
Commercial Loans and Leases [Member]
Loans And Leases Receivable [Line Items]
Loans pledged to secure outstanding borrowings from the FHLB of New York	$ 11,900,000,000
Residential Mortgage Loans [Member]
Loans And Leases Receivable [Line Items]
Loans pledged to secure outstanding borrowings from the FHLB of New York	11,500,000,000
Home Equity Loans and Lines of Credit [Member]
Loans And Leases Receivable [Line Items]
Loans pledged to secure outstanding borrowings from the FHLB of New York	2,300,000,000
Other Consumer Loans [Member]
Loans And Leases Receivable [Line Items]
Loans pledged to secure outstanding borrowings from the FHLB of New York	$ 7,500,000,000
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	$ 28,000,000	$ 77,000,000
New borrowings by directors, certain officers and their associates	1,000,000
Repayments and other reductions of borrowings by directors, certain officers and their associates	$ 50,000,000
Maximum [Member]
Loans And Leases Receivable [Line Items]
Purchased impaired loans as a percentage of total assets	1.00%	1.00%
Commercial Real Estate [Member]
Loans And Leases Receivable [Line Items]
Loans serviced for others sold with credit recourse	$ 3,900,000,000
Loans pledged to secure outstanding borrowings from the FHLB of New York	13,300,000,000
Residential Mortgage Loans [Member]
Loans And Leases Receivable [Line Items]
Mortgage loans held for sale	414,000,000	$ 205,000,000
RealEstateLoanMember
Loans And Leases Receivable [Line Items]
Mortgage loans held for sale	$ 28,000,000	$ 347,000,000

Loans and Leases - Summary of Current, Past Due and Nonaccrual Loans (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	$ 87,999,720	$ 86,140,950
30-89 Days Past Due	1,174,132	866,337
Accruing Loans Past Due 90 Days or More	518,728	222,527
Purchased Impaired	227,545	303,305
Nonaccrual	963,112	893,608
Loans and leases, net of unearned discount	90,922,869	88,466,477
Accruing Loans Acquired at Discount [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing Loans Past Due 90 Days or More	39,632	39,750
Commercial, Financial, Leasing, etc. [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	23,290,797	22,701,020
30-89 Days Past Due	184,011	39,798
Accruing Loans Past Due 90 Days or More	16,776	2,567
Nonaccrual	346,557	234,423
Loans and leases, net of unearned discount	23,838,168	22,977,976
Commercial, Financial, Leasing, etc. [Member] \| Accruing Loans Acquired at Discount [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing Loans Past Due 90 Days or More	27	168
Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	26,311,414	25,250,983
30-89 Days Past Due	165,579	134,474
Accruing Loans Past Due 90 Days or More	6,740	11,457
Purchased Impaired	15,601	9,769
Nonaccrual	158,474	203,672
Loans and leases, net of unearned discount	26,657,808	25,610,365
Commercial [Member] \| Accruing Loans Acquired at Discount [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing Loans Past Due 90 Days or More		10
Residential Builder and Developer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	1,521,315	1,665,178
30-89 Days Past Due	21,195	20,333
Purchased Impaired	753
Nonaccrual	3,982	4,798
Loans and leases, net of unearned discount	1,547,245	1,690,309
Other Commercial Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	7,204,148	6,982,077
30-89 Days Past Due	95,346	43,615
Accruing Loans Past Due 90 Days or More	3,360	14,344
Purchased Impaired	1,237	641
Nonaccrual	32,770	22,205
Loans and leases, net of unearned discount	7,336,861	7,062,882
Residential [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	12,760,040	13,591,790
30-89 Days Past Due	451,274	404,808
Accruing Loans Past Due 90 Days or More	486,515	189,682
Purchased Impaired	143,145	203,044
Nonaccrual	235,663	233,352
Loans and leases, net of unearned discount	14,082,425	14,629,326
Residential [Member] \| Accruing Loans Acquired at Discount [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing Loans Past Due 90 Days or More	5,788	6,650
Residential Limited Documentation [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	1,858,037	2,278,040
30-89 Days Past Due	65,215	72,544
Accruing Loans Past Due 90 Days or More	181
Purchased Impaired	66,809	89,851
Nonaccrual	83,427	84,685
Loans and leases, net of unearned discount	2,073,669	2,525,120
Home Equity Lines and Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	4,386,511	4,758,513
30-89 Days Past Due	30,229	25,416
Nonaccrual	63,215	71,292
Loans and leases, net of unearned discount	4,481,617	4,860,254
Home Equity Lines and Loans [Member] \| Accruing Loans Acquired at Discount [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing Loans Past Due 90 Days or More	1,662	5,033
Recreational Finance [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	5,484,997	4,085,781
30-89 Days Past Due	36,827	29,947
Nonaccrual	14,219	11,199
Loans and leases, net of unearned discount	5,536,142	4,127,162
Recreational Finance [Member] \| Accruing Loans Acquired at Discount [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing Loans Past Due 90 Days or More	99	235
Automobile [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	3,787,221	3,555,757
30-89 Days Past Due	78,478	79,804
Nonaccrual	21,293	23,359
Loans and leases, net of unearned discount	3,886,992	3,658,920
Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	1,395,240	1,271,811
30-89 Days Past Due	45,978	15,598
Accruing Loans Past Due 90 Days or More	5,156	4,477
Nonaccrual	3,512	4,623
Loans and leases, net of unearned discount	1,481,942	1,324,163
Other [Member] \| Accruing Loans Acquired at Discount [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing Loans Past Due 90 Days or More	$ 32,056	$ 27,654

Loans and Leases - Summary of Changes in Accretable Yield for Acquired Loans (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Purchased Impaired [Member]
Summary of changes in Accretable Yield for acquired loans
Balance at beginning of period	$ 147,210	$ 157,918	$ 154,233
Interest income	(49,017)	(37,819)	(47,452)
Reclassifications from nonaccretable balance	36,718	27,111	51,137
Balance at end of period	134,911	147,210	157,918
Other Acquired [Member]
Summary of changes in Accretable Yield for acquired loans
Balance at beginning of period	96,907	133,162	201,153
Interest income	(36,452)	(63,856)	(82,605)
Reclassifications from nonaccretable balance	15,534	22,849	16,437
Other	(3,909)	4,752	(1,823)
Balance at end of period	$ 72,080	$ 96,907	$ 133,162

Loans and Leases - Loan Modification Activities that were Considered Troubled Debt Restructurings (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($) Modification	Dec. 31, 2018 USD ($) Modification	Dec. 31, 2017 USD ($) Modification
Financing Receivable, Modifications [Line Items]
Number of modifications \| Modification	412	557	654
Pre-modification Recorded Investment	$ 143,556	$ 175,583	$ 216,063
Post- modification	$ 127,024	$ 180,224	$ 191,522
Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications \| Modification	51	83	83
Pre-modification Recorded Investment	$ 48,315	$ 30,217	$ 44,924
Post- modification	$ 31,345	$ 30,731	$ 40,882
Commercial, Financial, Leasing, etc. [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications \| Modification	150	203	217
Pre-modification Recorded Investment	$ 63,715	$ 102,445	$ 111,036
Post- modification	$ 63,356	$ 102,914	$ 88,663
Other Commercial Construction [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications \| Modification	3	1	2
Pre-modification Recorded Investment	$ 1,559	$ 752	$ 168
Post- modification	$ 1,500	$ 746	$ 168
Residential [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications \| Modification	83	134	141
Pre-modification Recorded Investment	$ 21,695	$ 34,798	$ 31,827
Post- modification	$ 22,726	$ 38,072	$ 34,607
Residential Limited Documentation [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications \| Modification	6	9	20
Pre-modification Recorded Investment	$ 1,409	$ 1,887	$ 4,230
Post- modification	$ 1,443	$ 2,250	$ 4,572
Home Equity Lines and Loans [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications \| Modification	41	47	110
Pre-modification Recorded Investment	$ 4,127	$ 3,952	$ 10,049
Post- modification	$ 4,180	$ 3,979	$ 10,213
Recreational Finance [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications \| Modification	10	7	9
Pre-modification Recorded Investment	$ 265	$ 202	$ 160
Post- modification	$ 265	$ 202	$ 160
Automobile [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications \| Modification	66	73	69
Pre-modification Recorded Investment	$ 1,141	$ 1,330	$ 1,378
Post- modification	$ 1,141	1,330	$ 1,378
Residential Builder and Developer [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications \| Modification	2		3
Pre-modification Recorded Investment	$ 1,330		$ 12,291
Post- modification	1,068		10,879
Principal Deferral [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	29,481	90,639	62,302
Principal Deferral [Member] \| Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	5,193	16,870	17,039
Principal Deferral [Member] \| Commercial, Financial, Leasing, etc. [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	10,485	50,490	25,051
Principal Deferral [Member] \| Other Commercial Construction [Member]
Financing Receivable, Modifications [Line Items]
Post- modification		746	168
Principal Deferral [Member] \| Residential [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	10,819	19,962	16,633
Principal Deferral [Member] \| Residential Limited Documentation [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	399	827	911
Principal Deferral [Member] \| Home Equity Lines and Loans [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	176	224	1,137
Principal Deferral [Member] \| Recreational Finance [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	265	202	160
Principal Deferral [Member] \| Automobile [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	1,076	1,318	1,203
Principal Deferral [Member] \| Residential Builder and Developer [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	1,068
Interest Rate Reduction [Member]
Financing Receivable, Modifications [Line Items]
Post- modification		978
Interest Rate Reduction [Member] \| Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Post- modification		175
Interest Rate Reduction [Member] \| Commercial, Financial, Leasing, etc. [Member]
Financing Receivable, Modifications [Line Items]
Post- modification		803
Other [Member]
Financing Receivable, Modifications [Line Items]
Post- modification		10,896	7,818
Other [Member] \| Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Post- modification		4,686	868
Other [Member] \| Commercial, Financial, Leasing, etc. [Member]
Financing Receivable, Modifications [Line Items]
Post- modification		6,210	6,459
Other [Member] \| Home Equity Lines and Loans [Member]
Financing Receivable, Modifications [Line Items]
Post- modification			491
Combination of Concession Types [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	97,543	77,711	121,402
Combination of Concession Types [Member] \| Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	26,152	9,000	22,975
Combination of Concession Types [Member] \| Commercial, Financial, Leasing, etc. [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	52,871	45,411	57,153
Combination of Concession Types [Member] \| Other Commercial Construction [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	1,500
Combination of Concession Types [Member] \| Residential [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	11,907	18,110	17,974
Combination of Concession Types [Member] \| Residential Limited Documentation [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	1,044	1,423	3,661
Combination of Concession Types [Member] \| Home Equity Lines and Loans [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	4,004	3,755	8,585
Combination of Concession Types [Member] \| Automobile [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	$ 65	$ 12	175
Combination of Concession Types [Member] \| Residential Builder and Developer [Member]
Financing Receivable, Modifications [Line Items]
Post- modification			$ 10,879

Loans and Leases - Summary of Lease Financing Receivables (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Direct financings:
Lease payments receivable	$ 1,164,567	$ 1,155,464
Estimated residual value of leased assets	84,540	85,169
Unearned income	(106,780)	(110,458)
Investment in direct financings	1,142,327	1,130,175
Leveraged leases:
Lease payments receivable	82,065	85,007
Estimated residual value of leased assets	81,025	81,261
Unearned income	(31,596)	(33,717)
Investment in leveraged leases	131,494	132,551
Total investment in leases	1,273,821	1,262,726
Deferred taxes payable arising from leveraged leases	$ 70,245	$ 74,995

Loans and Leases - Minimum Future Lease Payments to be Received from Lease Financings (Detail) $ in Thousands	Dec. 31, 2019 USD ($)
Receivables [Abstract]
2020	$ 332,719
2021	297,875
2022	227,652
2023	161,296
2024	84,433
Later years	142,657
Total	$ 1,246,632

Allowance for Credit Losses - Changes in Allowance for Credit Losses (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	$ 1,019,444	$ 1,017,198	$ 988,997
Provision for credit losses	176,000	132,000	168,000
Net charge-offs
Charge-offs	(237,708)	(231,241)	(224,598)
Recoveries	93,335	101,487	84,799
Net (charge-offs) recoveries	(144,373)	(129,754)	(139,799)
Ending balance	1,051,071	1,019,444	1,017,198
Commercial, Financial, Leasing, etc. [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	330,055	328,599	330,833
Provision for credit losses	69,702	33,967	41,511
Net charge-offs
Charge-offs	(58,244)	(60,414)	(64,941)
Recoveries	24,581	27,903	21,196
Net (charge-offs) recoveries	(33,663)	(32,511)	(43,745)
Ending balance	366,094	330,055	328,599
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	341,655	374,085	362,719
Provision for credit losses	(10,726)	(41,181)	6,715
Net charge-offs
Charge-offs	(12,664)	(12,286)	(7,931)
Recoveries	3,936	21,037	12,582
Net (charge-offs) recoveries	(8,728)	8,751	4,651
Ending balance	322,201	341,655	374,085
Residential Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	69,125	65,405	61,127
Provision for credit losses	(8,585)	12,401	16,094
Net charge-offs
Charge-offs	(12,711)	(15,345)	(20,799)
Recoveries	8,204	6,664	8,983
Net (charge-offs) recoveries	(4,507)	(8,681)	(11,816)
Ending balance	56,033	69,125	65,405
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	200,564	170,809	156,288
Provision for credit losses	126,029	127,068	103,410
Net charge-offs
Charge-offs	(154,089)	(143,196)	(130,927)
Recoveries	56,614	45,883	42,038
Net (charge-offs) recoveries	(97,475)	(97,313)	(88,889)
Ending balance	229,118	200,564	170,809
Unallocated [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	78,045	78,300	78,030
Provision for credit losses	(420)	(255)	270
Net charge-offs
Ending balance	$ 77,625	$ 78,045	$ 78,300

Allowance for Credit Losses - Impaired Loans and Leases (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Financing Receivable Impaired [Line Items]
Recorded investment with related allowance	$ 562,457	$ 542,255
Unpaid principal balance with related allowance	660,893	630,609
Related allowance	104,466	79,646
Recorded investment with no related allowance	303,676	254,196
Unpaid principal balance with no related allowance	339,935	305,559
Recorded investment	866,133	796,451
Unpaid principal balance	1,000,828	936,168
Commercial Real Estate [Member]
Financing Receivable Impaired [Line Items]
Recorded investment with related allowance	60,745	110,253
Unpaid principal balance with related allowance	73,026	125,117
Related allowance	7,713	11,937
Recorded investment with no related allowance	117,751	113,376
Unpaid principal balance with no related allowance	131,406	124,657
Recorded investment	178,496	223,629
Unpaid principal balance	204,432	249,774
Automobile [Member]
Financing Receivable Impaired [Line Items]
Recorded investment with related allowance	3,256	3,527
Unpaid principal balance with related allowance	3,344	3,599
Related allowance	703	729
Recorded investment	3,256	3,527
Unpaid principal balance	3,344	3,599
Commercial, Financial, Leasing, etc. [Member]
Financing Receivable Impaired [Line Items]
Recorded investment with related allowance	230,444	153,478
Unpaid principal balance with related allowance	257,745	175,549
Related allowance	74,435	46,034
Recorded investment with no related allowance	139,127	105,507
Unpaid principal balance with no related allowance	152,132	136,128
Recorded investment	369,571	258,985
Unpaid principal balance	409,877	311,677
Residential Builder and Developer [Member]
Financing Receivable Impaired [Line Items]
Recorded investment with related allowance	9,559	5,981
Unpaid principal balance with related allowance	9,856	6,557
Related allowance	121	462
Recorded investment with no related allowance	3,378	2,593
Unpaid principal balance with no related allowance	3,378	2,602
Recorded investment	12,937	8,574
Unpaid principal balance	13,234	9,159
Other Commercial Construction [Member]
Financing Receivable Impaired [Line Items]
Recorded investment with related allowance	12,425	10,563
Unpaid principal balance with related allowance	24,908	11,113
Related allowance	1,354	640
Recorded investment with no related allowance	20,345	11,710
Unpaid principal balance with no related allowance	21,306	11,880
Recorded investment	32,770	22,273
Unpaid principal balance	46,214	22,993
Residential [Member]
Financing Receivable Impaired [Line Items]
Recorded investment with related allowance	125,623	124,974
Unpaid principal balance with related allowance	145,497	147,817
Related allowance	6,873	5,402
Recorded investment with no related allowance	18,090	15,379
Unpaid principal balance with no related allowance	23,365	20,496
Recorded investment	143,713	140,353
Unpaid principal balance	168,862	168,313
Residential Limited Documentation [Member]
Financing Receivable Impaired [Line Items]
Recorded investment with related allowance	64,268	74,156
Unpaid principal balance with related allowance	77,359	90,066
Related allowance	2,300	3,000
Recorded investment with no related allowance	4,985	5,631
Unpaid principal balance with no related allowance	8,348	9,796
Recorded investment	69,253	79,787
Unpaid principal balance	85,707	99,862
Home Equity Lines and Loans [Member]
Financing Receivable Impaired [Line Items]
Recorded investment with related allowance	46,325	47,982
Unpaid principal balance with related allowance	51,238	53,248
Related allowance	8,957	9,135
Recorded investment	46,325	47,982
Unpaid principal balance	51,238	53,248
Recreational Finance [Member]
Financing Receivable Impaired [Line Items]
Recorded investment with related allowance	5,270	6,138
Unpaid principal balance with related allowance	9,579	9,163
Related allowance	1,095	1,261
Recorded investment	5,270	6,138
Unpaid principal balance	9,579	9,163
Other [Member]
Financing Receivable Impaired [Line Items]
Recorded investment with related allowance	4,542	5,203
Unpaid principal balance with related allowance	8,341	8,380
Related allowance	915	1,046
Recorded investment	4,542	5,203
Unpaid principal balance	$ 8,341	$ 8,380

Allowance for Credit Losses - Interest Income Recognized on Impaired Loans (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment	$ 827,359	$ 754,197	$ 748,598
Interest income recognized, Total	33,400	41,461	31,983
Interest income recognized, Cash basis	20,619	29,565	21,316
Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment	208,200	194,451	207,616
Interest income recognized, Total	5,850	10,880	4,497
Interest income recognized, Cash basis	5,850	10,880	4,497
Commercial, Financial, Leasing, etc. [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment	303,712	263,018	240,157
Interest income recognized, Total	8,960	7,873	3,894
Interest income recognized, Cash basis	8,960	7,873	3,894
Residential Builder and Developer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment	10,863	8,699	16,209
Interest income recognized, Total	357	1,779	6,419
Interest income recognized, Cash basis	357	1,779	6,419
Other Commercial Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment	26,440	11,467	15,142
Interest income recognized, Total	634	3,474	1,001
Interest income recognized, Cash basis	634	3,474	1,001
Residential [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment	142,400	129,593	110,646
Interest income recognized, Total	9,200	8,386	7,177
Interest income recognized, Cash basis	3,567	3,456	3,406
Residential Limited Documentation [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment	74,399	82,854	93,097
Interest income recognized, Total	5,463	6,118	5,981
Interest income recognized, Cash basis	881	1,723	1,607
Home Equity Lines and Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment	47,168	48,591	47,323
Interest income recognized, Total	1,639	1,698	1,681
Interest income recognized, Cash basis	270	289	400
Recreational Finance [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment	5,707	1,849	1,041
Interest income recognized, Total	558	333	212
Interest income recognized, Cash basis	17	9	9
Automobile [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment	3,445	9,262	15,045
Interest income recognized, Total	214	690	1,025
Interest income recognized, Cash basis	72	69	81
Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment	5,025	4,413	2,322
Interest income recognized, Total	525	230	96
Interest income recognized, Cash basis	$ 11	$ 13	$ 2

Allowance for Credit Losses - Summary of Loan Grades (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	$ 90,922,869	$ 88,466,477
Commercial, Financial, Leasing, etc. [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	23,838,168	22,977,976
Commercial, Financial, Leasing, etc. [Member] \| Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	22,595,821	21,693,705
Commercial, Financial, Leasing, etc. [Member] \| Criticized Accrual [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	895,790	1,049,848
Commercial, Financial, Leasing, etc. [Member] \| Criticized Nonaccrual [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	346,557	234,423
Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	26,657,808	25,610,365
Commercial [Member] \| Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	25,728,725	24,539,706
Commercial [Member] \| Criticized Accrual [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	770,609	866,987
Commercial [Member] \| Criticized Nonaccrual [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	158,474	203,672
Residential Builder and Developer [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	1,547,245	1,690,309
Residential Builder and Developer [Member] \| Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	1,419,162	1,546,002
Residential Builder and Developer [Member] \| Criticized Accrual [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	124,101	139,509
Residential Builder and Developer [Member] \| Criticized Nonaccrual [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	3,982	4,798
Other Commercial Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	7,336,861	7,062,882
Other Commercial Construction [Member] \| Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	7,092,799	6,890,562
Other Commercial Construction [Member] \| Criticized Accrual [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	211,292	150,115
Other Commercial Construction [Member] \| Criticized Nonaccrual [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	$ 32,770	$ 22,205

Allowance for Credit Losses - Allocation of Allowance for Credit Losses on Basis of Company's Impairment Methodology (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses	$ 104,466	$ 79,646
Allowance for credit losses	865,776	849,356
Allowance for credit losses	1,051,071	1,019,444	$ 1,017,198	$ 988,997
Purchased Impaired [Member] \| Receivables Acquired with Deteriorated Credit Quality [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses	3,204	12,397
Allocated [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses	973,446	941,399
Unallocated [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses	77,625	78,045	$ 78,300	$ 78,030
Commercial, Financial, Leasing, etc. [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses	74,435	46,034
Allowance for credit losses	291,659	284,021
Commercial, Financial, Leasing, etc. [Member] \| Allocated [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses	366,094	330,055
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses	9,188	13,039
Allowance for credit losses	313,013	328,616
Commercial Real Estate [Member] \| Allocated [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses	322,201	341,655
Residential Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses	9,173	8,402
Allowance for credit losses	43,656	48,326
Residential Real Estate [Member] \| Purchased Impaired [Member] \| Receivables Acquired with Deteriorated Credit Quality [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses	3,204	12,397
Residential Real Estate [Member] \| Allocated [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses	56,033	69,125
Consumer Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses	11,670	12,171
Allowance for credit losses	217,448	188,393
Consumer Loans [Member] \| Allocated [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses	$ 229,118	$ 200,564

Allowance for Credit Losses - Recorded Investment in Loans and Leases on Basis of Company's Impairment Methodology (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	$ 90,922,869	$ 88,466,477
Individually Evaluated for Impairment [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	866,133	796,451
Collectively Evaluated for Impairment [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	89,829,191	87,366,721
Purchased Impaired [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	227,545	303,305
Commercial, Financial, Leasing, etc. [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	23,838,168	22,977,976
Commercial, Financial, Leasing, etc. [Member] \| Individually Evaluated for Impairment [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	369,571	258,985
Commercial, Financial, Leasing, etc. [Member] \| Collectively Evaluated for Impairment [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	23,468,597	22,718,991
Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	35,541,914	34,363,556
Commercial Real Estate [Member] \| Individually Evaluated for Impairment [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	224,203	254,476
Commercial Real Estate [Member] \| Collectively Evaluated for Impairment [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	35,300,120	34,098,670
Commercial Real Estate [Member] \| Purchased Impaired [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	17,591	10,410
Residential Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	16,156,094	17,154,446
Residential Real Estate [Member] \| Individually Evaluated for Impairment [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	212,966	220,140
Residential Real Estate [Member] \| Collectively Evaluated for Impairment [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	15,733,174	16,641,411
Residential Real Estate [Member] \| Purchased Impaired [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	209,954	292,895
Consumer Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	15,386,693	13,970,499
Consumer Loans [Member] \| Individually Evaluated for Impairment [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	59,393	62,850
Consumer Loans [Member] \| Collectively Evaluated for Impairment [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	$ 15,327,300	$ 13,907,649

Premises and Equipment - Summary of Premises and Equipment (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Land	$ 96,118	$ 97,082
Buildings	482,182	465,482
Leasehold improvements	262,438	240,731
Premises and equipment, gross	1,594,694	1,491,659
Less: accumulated depreciation and amortization	890,697	844,251
Right of use assets — operating leases	436,927
Premises and equipment, net	1,140,924	647,408
Owned Assets [Member]
Property, Plant and Equipment [Line Items]
Furniture and equipment	739,724	669,782
Less: accumulated depreciation and amortization	882,272	835,218
Capital Leases [Member]
Property, Plant and Equipment [Line Items]
Furniture and equipment	14,232	18,582
Less: accumulated depreciation and amortization	$ 8,425	$ 9,033

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) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($)
Lease cost
Operating lease cost	$ 100,669
Short-term lease cost	105
Variable lease cost	2,332
Total lease cost	103,106
Other information
Right-of-use assets obtained in exchange for new operating lease liabilities	132,219
Cash paid toward lease liabilities	$ 101,869
Weighted-average remaining lease term	7 years
Weighted-average discount rate	3.01%

Premises and Equipment - Summary of Minimum Lease Payments Under Noncancelable Operating Leases (Detail) $ in Thousands	Dec. 31, 2019 USD ($)
Property Plant And Equipment Capitalized Interest Costs [Abstract]
2020	$ 100,447
2021	95,199
2022	79,794
2023	62,766
2024	50,539
Later years	154,585
Total lease payments	543,330
Less: imputed interest	55,775
Operating lease liabilities	$ 487,555

Capitalized Servicing Assets - Changes in Capitalized Servicing Assets (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Residential Mortgage Loans [Member]
Servicing Asset at Amortized Cost [Line Items]
Amortized value, Beginning balance	$ 120,509	$ 114,978	$ 117,351
Originations	26,067	28,985	28,792
Purchases	144,326	454	699
Amortization	(46,491)	(23,908)	(31,864)
Amortized value, ending balance	244,411	120,509	114,978
Valuation allowance	(7,000)
Ending balance, net	237,411	120,509	114,978
Commercial Mortgage Loans [Member]
Servicing Asset at Amortized Cost [Line Items]
Amortized value, Beginning balance	114,663	114,076	103,764
Originations	41,370	26,298	34,620
Amortization	(25,397)	(25,711)	(24,308)
Amortized value, ending balance	130,636	114,663	114,076
Ending balance, net	$ 130,636	$ 114,663	$ 114,076

Capitalized Servicing Assets - Additional Information (Detail) - USD ($) $ in Millions				12 Months Ended
	Dec. 31, 2019	Jan. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Residential Mortgage Loans [Member]
Servicing Assets at Fair Value [Line Items]
Mortgage loans serviced for others	$ 32,300		$ 22,200	$ 32,300	$ 22,200	$ 22,600
Fair value of residential loan servicing assets	$ 297		$ 240	$ 297	$ 240
Weighted average discount rates used to estimate fair value of capitalized mortgaged loan servicing assets	10.60%		11.40%
Residential Mortgage Loans [Member] \| LIBOR [Member]
Servicing Assets at Fair Value [Line Items]
Discounted rate represented weighted-average option-adjusted basis spread point percentage				9.28%	9.63%
Residential Mortgage Sub Servicing Loan [Member]
Servicing Assets at Fair Value [Line Items]
Mortgage loans serviced for others	$ 62,800		$ 56,800	$ 62,800	$ 56,800	56,600
Residential Real Estate [Member]
Servicing Assets at Fair Value [Line Items]
Fair value of residential loan servicing assets		$ 13,300
Purchase price of servicing rights		$ 144
Commercial Mortgage Loans [Member]
Servicing Assets at Fair Value [Line Items]
Mortgage loans serviced for others	17,600		15,500	17,600	15,500	13,600
Fair value of residential loan servicing assets	$ 153		$ 135	$ 153	135
Weighted average discount rates used to estimate fair value of capitalized mortgaged loan servicing assets	18.00%		18.00%	18.00%
Commercial Mortgage Sub Servicing Loan [Member]
Servicing Assets at Fair Value [Line Items]
Mortgage loans serviced for others	$ 3,400		$ 2,700	$ 3,400	$ 2,700	$ 2,600

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 Thousands			12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019
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			15.84%
Impact on fair value of 10% adverse change	$ (16,555)		$ (16,555)
Impact on fair value of 20% adverse change	$ (31,475)		$ (31,475)
Weighted-average OAS	9.28%		9.28%
Impact on fair value of 10% adverse change	$ (8,070)		$ (8,070)
Impact on fair value of 20% adverse change	$ (15,663)		$ (15,663)
Weighted-average discount rate	10.60%	11.40%
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	18.00%	18.00%	18.00%
Impact on fair value of 10% adverse change	$ (6,948)		$ (6,948)
Impact on fair value of 20% adverse change	$ (13,395)		$ (13,395)

Goodwill and Other Intangible Assets - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Goodwill And Other Intangible Assets [Line Items]
Reduction in gross carrying amount and accumulated amortization of intangible assets	$ 933,000
Amortization of core deposit and other intangible assets	$ 19,490	$ 24,522	$ 31,366
Minimum [Member]
Goodwill And Other Intangible Assets [Line Items]
Estimated useful lives	5 years
Maximum [Member]
Goodwill And Other Intangible Assets [Line Items]
Estimated useful lives	10 years
Core Deposit and Other Intangible Assets [Member]
Goodwill And Other Intangible Assets [Line Items]
Estimated useful lives	8 years
Amortization of core deposit and other intangible assets	$ 19,000	$ 25,000	$ 31,000
Core Deposit and Other Intangible Assets [Member] \| Minimum [Member]
Goodwill And Other Intangible Assets [Line Items]
Estimated useful lives	3 years
Core Deposit and Other Intangible Assets [Member] \| Maximum [Member]
Goodwill And Other Intangible Assets [Line Items]
Estimated useful lives	10 years

Goodwill and Other Intangible Assets - Total Amortizing Intangible Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 138,421	$ 1,070,027
Accumulated Amortization	109,387	1,022,960
Net Carrying Amount	29,034	47,067
Core Deposit [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	131,664	887,459
Accumulated Amortization	105,802	843,572
Net Carrying Amount	25,862	43,887
Other [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	6,757	182,568
Accumulated Amortization	3,585	179,388
Net Carrying Amount	$ 3,172	$ 3,180

Goodwill and Other Intangible Assets - Estimated Amortization Expense in Future Years (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Goodwill And Intangible Assets Disclosure [Abstract]
2020	$ 14,869
2021	10,167
2022	3,998
Net Carrying Amount	$ 29,034	$ 47,067

Borrowings - Amounts and Interest Rates of Short-term Borrowings (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Schedule Of Borrowings [Line Items]
Weighted-average interest rate	0.14%	2.58%	0.92%
Daily-average amount outstanding	$ 1,059,390,000	$ 330,665,000	$ 204,623,000
Weighted-average interest rate	2.34%	1.63%	0.74%
Federal funds purchased and short term borrowings	$ 62,363,000	$ 4,398,378,000	$ 175,099,000
Federal Funds Purchased and Repurchase Agreements [Member]
Schedule Of Borrowings [Line Items]
Weighted-average interest rate	0.14%	1.68%	0.92%
Highest amount at a month-end	$ 3,402,566,000	$ 2,654,416,000	$ 204,977,000
Daily-average amount outstanding	$ 260,322,000	$ 261,200,000	$ 188,459,000
Weighted-average interest rate	1.86%	1.49%	0.69%
Federal Funds Purchased and Repurchase Agreements	$ 62,363,000	$ 198,378,000	$ 175,099,000
Other Short-term Borrowings [Member]
Schedule Of Borrowings [Line Items]
Weighted-average interest rate		2.63%
Highest amount at a month-end	5,000,000,000	$ 4,200,000,000	1,500,000,000
Daily-average amount outstanding	$ 799,068,000	$ 69,465,000	$ 16,164,000
Weighted-average interest rate	2.49%	2.16%	1.27%
Other Short-term Borrowings		$ 4,200,000,000

Borrowings - Additional Information (Detail) - USD ($)	12 Months Ended
Borrowings - Additional Information (Detail) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Contractual interest rates of long-term agreements to repurchase securities	4.29%
Minimum contractual interest rates of long-term agreements to repurchase securities		4.09%
Maximum contractual interest rates of long-term agreements to repurchase securities		4.58%
Repurchase dates of the long-term agreements outstanding	2020
Collateral posted	$ 108,000,000	$ 428,000,000
Debt Maturity, Start Year	Jan. 01, 2027
Debt Maturity, End Year	Dec. 31, 2033
Minimum [Member]
Debt Instrument [Line Items]
Variable interest rate of Senior Notes /Junior Subordinated Debentures	2.76%	3.39%
Maximum [Member]
Debt Instrument [Line Items]
Variable interest rate of Senior Notes /Junior Subordinated Debentures	5.34%	5.69%
FHLBs Facility [Member]
Debt Instrument [Line Items]
Borrowing facilities available with FHLB's amount	$ 18,200,000,000
Federal Reserve Bank of New York [Member]
Debt Instrument [Line Items]
Line of credit facility	$ 14,400,000,000
Senior Notes Issued in July 2018 [Member]
Debt Instrument [Line Items]
Variable interest rate of Senior Notes /Junior Subordinated Debentures	2.62%	2.51%
Variable Rate Senior Notes [Member]
Debt Instrument [Line Items]
Weighted-average variable rates payable	2.34%	2.96%
Variable Rate Senior Notes [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Variable interest rate of Senior Notes /Junior Subordinated Debentures	2.21%	2.76%
Variable Rate Senior Notes [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Variable interest rate of Senior Notes /Junior Subordinated Debentures	2.54%	3.25%
Long Term Fixed Rate Advances From Fhlb
Debt Instrument [Line Items]
Advances from the FHLB earliest maturity date	2029
Advances from the FHLB latest maturity date,	2035
Long Term Fixed Rate Advances From Fhlb \| Weighted Average [Member]
Debt Instrument [Line Items]
Variable contractual interest rate of long-term debt	5.82%	2.06%
Subordinated Capital Notes [Member]
Debt Instrument [Line Items]
Interest rate of debt instrument	3.02%	3.72%
Subordinated Variable Rate Notes Due 2021 [Member]
Debt Instrument [Line Items]
Interest rate of debt instrument	2.55%	3.38%
Junior Subordinated Debt [Member]
Debt Instrument [Line Items]
Weighted-average variable rates payable	3.37%	3.94%
Short-term Borrowings [Member]
Debt Instrument [Line Items]
Stated maturity	1 year

Borrowings - Lines of Credit Under Formal Agreements (Detail) - M&T Bank [Member] $ in Thousands	Dec. 31, 2019 USD ($)
Schedule Of Borrowings [Line Items]
Outstanding borrowings	$ 1,869
Unused	$ 32,578,083

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References + Details

Borrowings - Long-term Borrowings (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Schedule Of Borrowings [Line Items]
Fixed rates advances from FHLB	$ 1,815	$ 576,446
Agreements to repurchase securities	101,679	409,154
Other	8,533	35,174
Long-term borrowings	6,986,186	8,444,914
Variable Rate Term Loans Due 2023 [Member] \| M&T Bank Corporation [Member]
Schedule Of Borrowings [Line Items]
Variable\fixed rates term loan amount	249,756	249,688
Variable Rate Term Loans Due 2021 [Member]
Schedule Of Borrowings [Line Items]
Variable\fixed rates term loan amount	349,893	349,794
3.55% Fixed Rate Due 2023 [Member] \| M&T Bank Corporation [Member]
Schedule Of Borrowings [Line Items]
Variable\fixed rates term loan amount	520,454	506,021
Variable Rate Term Loans Due 2022 [Member]
Schedule Of Borrowings [Line Items]
Variable\fixed rates term loan amount	249,758	249,658
Fixed Rate Term Loans 2.25% Due 2019 [Member]
Schedule Of Borrowings [Line Items]
Variable\fixed rates term loan amount		645,801
Fixed Rate Term Loans 2.05% Due 2020 [Member]
Schedule Of Borrowings [Line Items]
Variable\fixed rates term loan amount	749,254	737,793
Fixed Rate Term Loans 2.10% Due 2020 [Member]
Schedule Of Borrowings [Line Items]
Variable\fixed rates term loan amount	749,864	741,965
Fixed Rate Term Loans 2.625% Due 2021 [Member]
Schedule Of Borrowings [Line Items]
Variable\fixed rates term loan amount	654,136	646,301
Fixed Rate Term Loans 2.50% Due 2022 [Member]
Schedule Of Borrowings [Line Items]
Variable\fixed rates term loan amount	652,714	634,525
Fixed Rate Term Loans 2.90% Due 2025 [Member]
Schedule Of Borrowings [Line Items]
Variable\fixed rates term loan amount	749,572	749,488
Variable Rate Due 2020 [Member]
Schedule Of Borrowings [Line Items]
Subordinated notes	409,361	409,361
Variable Rate Due 2021 [Member]
Schedule Of Borrowings [Line Items]
Subordinated notes	500,000	500,000
3.40% due 2027 [Member]
Schedule Of Borrowings [Line Items]
Subordinated notes	514,353	481,692
BSB Capital Trust I - 8.125%, due 2028 [Member]
Schedule Of Borrowings [Line Items]
Junior subordinated debentures associated with preferred capital securities	15,728	15,705
Provident Trust I - 8.29%, due 2028 [Member]
Schedule Of Borrowings [Line Items]
Junior subordinated debentures associated with preferred capital securities	28,235	27,489
Southern Financial Statutory Trust I - 10.60%, due 2030 [Member]
Schedule Of Borrowings [Line Items]
Junior subordinated debentures associated with preferred capital securities	6,770	6,713
First Maryland Capital I - due 2027 [Member]
Schedule Of Borrowings [Line Items]
Junior subordinated debentures associated with preferred capital securities	147,871	147,333
First Maryland Capital II - due 2027 [Member]
Schedule Of Borrowings [Line Items]
Junior subordinated debentures associated with preferred capital securities	149,943	149,280
Allfirst Asset Trust - due 2029 [Member]
Schedule Of Borrowings [Line Items]
Junior subordinated debentures associated with preferred capital securities	96,930	96,785
BSB Capital Trust III - due 2033 [Member]
Schedule Of Borrowings [Line Items]
Junior subordinated debentures associated with preferred capital securities	15,464	15,464
Provident Statutory Trust III - Due 2033 [Member]
Schedule Of Borrowings [Line Items]
Junior subordinated debentures associated with preferred capital securities	55,867	55,143
Southern Financial Capital Trust III - due 2033 [Member]
Schedule Of Borrowings [Line Items]
Junior subordinated debentures associated with preferred capital securities	$ 8,236	$ 8,141

Borrowings - Long-term Borrowings (Parenthetical) (Detail)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Variable Rate Term Loans Due 2023 [Member] \| M&T Bank Corporation [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2023	2023
Variable Rate Term Loans Due 2021 [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2021	2021
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%
Variable Rate Term Loans Due 2022 [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2022	2022
Fixed Rate Term Loans 2.25% Due 2019 [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2019	2019
Interest rate of debt instrument	2.25%	2.25%
Fixed Rate Term Loans 2.10% Due 2020 [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2020	2020
Interest rate of debt instrument	2.10%	2.10%
Fixed Rate Term Loans 2.05% Due 2020 [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2020	2020
Interest rate of debt instrument	2.05%	2.05%
Fixed Rate Term Loans 2.625% Due 2021 [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2021	2021
Interest rate of debt instrument	2.625%	2.625%
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 2.50% Due 2022 [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2022	2022
Interest rate of debt instrument	2.50%	2.50%
Variable Rate Due 2020 [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2020	2020
Variable Rate Due 2021 [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2021	2021
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

Borrowings - Maturity of Long-term Borrowings (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Debt Disclosure [Abstract]
2020	$ 2,010,251
2021	1,506,667
2022	907,794
2023	770,211
2024	479
Later years	1,790,784
Long-term borrowings	$ 6,986,186	$ 8,444,914

Shareholders' Equity - Issued and Outstanding Preferred Stock (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Class Of Stock [Line Items]
Carrying Value	$ 1,250,000	$ 1,231,500
Series A Fixed Rate Cumulative Perpetual Preferred Stock [Member]
Class Of Stock [Line Items]
Preferred stock, Shares Issued		230,000
Preferred stock, Shares Outstanding		230,000
Carrying Value		$ 230,000
Series C Fixed Rate Cumulative Perpetual Preferred Stock [Member]
Class Of Stock [Line Items]
Preferred stock, Shares Issued		151,500
Preferred stock, Shares Outstanding		151,500
Carrying Value		$ 151,500
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	$ 350,000	$ 350,000
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	$ 500,000	$ 500,000
Series G Fixed-Rate Reset Non-cumulative Perpetual Preferred Stock [Member]
Class Of Stock [Line Items]
Preferred stock, Shares Issued	40,000
Preferred stock, Shares Outstanding	40,000
Carrying Value	$ 400,000

Shareholders' Equity - Issued and Outstanding Preferred Stock (Parenthetical) (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Series A Fixed Rate Cumulative Perpetual Preferred Stock [Member]
Class Of Stock [Line Items]
Preferred stock, liquidation preference per share	$ 1,000	$ 1,000
Preferred stock, dividend declared per share	47.8125	63.75	$ 63.75
Series C Fixed Rate Cumulative Perpetual Preferred Stock [Member]
Class Of Stock [Line Items]
Preferred stock, liquidation preference per share	1,000	1,000
Preferred stock, dividend declared per share	47.8125	63.75	63.75
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 declared per share	$ 64.50	$ 64.50	64.50
Preferred stock dividend rate	6.45%	6.45%
Date of change in the dividend rate	Feb. 14, 2024	Feb. 14, 2024
London Interbank offered rate plus basis points	3.61%	3.61%
Preferred shares redemption date	Feb. 15, 2024	Feb. 15, 2024
Preferred Stock, Redemption Feature, Redemption Term	90 days	90 days
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 declared per share	$ 512.50	$ 512.50	$ 512.50
Preferred stock dividend rate	5.125%	5.125%
Date of change in the dividend rate	Oct. 31, 2026	Oct. 31, 2026
London Interbank offered rate plus basis points	3.52%	3.52%
Preferred shares redemption date	Nov. 01, 2026	Nov. 01, 2026
Preferred Stock, Redemption Feature, Redemption Term	90 days	90 days
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 declared per share	$ 125.694
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
U S treasury rate plus additional rate	3.174%	3.174%
Dividend payment terms	five-year	five-year

Revenue from Contracts with Customers - Summary of Sources of Noninterest Income that are Subject to Noted Accounting Guidance (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disaggregation Of Revenue [Line Items]
Brokerage services income	$ 48,922	$ 51,069	$ 61,445
Other revenues from operations:
Total other income	2,061,679	1,856,000	1,851,143
Service Charges on Deposit Accounts [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	432,978	429,337	427,372
Trust Income [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	572,608	537,585	$ 501,381
ASU 2014-09 [Member]
Disaggregation Of Revenue [Line Items]
Brokerage services income	48,922	51,069
Other revenues from operations:
Merchant discount and credit card fees	107,042	105,953
Other	91,613	90,369
Total other income	1,253,163	1,214,313
ASU 2014-09 [Member] \| Service Charges on Deposit Accounts [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	432,978	429,337
ASU 2014-09 [Member] \| Trust Income [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	572,608	537,585
ASU 2014-09 [Member] \| Business Banking [Member]
Other revenues from operations:
Merchant discount and credit card fees	36,844	34,557
Total other income	97,565	96,889
ASU 2014-09 [Member] \| Business Banking [Member] \| Service Charges on Deposit Accounts [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	60,690	62,323
ASU 2014-09 [Member] \| Business Banking [Member] \| Trust Income [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	31	9
ASU 2014-09 [Member] \| Commercial Banking [Member]
Other revenues from operations:
Merchant discount and credit card fees	52,161	52,051
Other	7,498	8,796
Total other income	153,666	158,171
ASU 2014-09 [Member] \| Commercial Banking [Member] \| Service Charges on Deposit Accounts [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	93,044	96,407
ASU 2014-09 [Member] \| Commercial Banking [Member] \| Trust Income [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	963	917
ASU 2014-09 [Member] \| Commercial Real Estate [Member]
Other revenues from operations:
Merchant discount and credit card fees	2,516	2,213
Other	8,615	7,259
Total other income	20,959	19,342
ASU 2014-09 [Member] \| Commercial Real Estate [Member] \| Service Charges on Deposit Accounts [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	9,828	9,870
ASU 2014-09 [Member] \| Discretionary Portfolio [Member]
Other revenues from operations:
Other	1,776	1,738
Total other income	1,776	1,738
ASU 2014-09 [Member] \| Residential Mortgage Banking [Member]
Other revenues from operations:
Other	3,492	3,814
Total other income	3,496	3,824
ASU 2014-09 [Member] \| Residential Mortgage Banking [Member] \| Service Charges on Deposit Accounts [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	4	10
ASU 2014-09 [Member] \| Retail Banking [Member]
Other revenues from operations:
Merchant discount and credit card fees	12,140	14,924
Other	36,144	38,529
Total other income	311,943	308,043
ASU 2014-09 [Member] \| Retail Banking [Member] \| Service Charges on Deposit Accounts [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	263,659	254,590
ASU 2014-09 [Member] \| All Other [Member]
Disaggregation Of Revenue [Line Items]
Brokerage services income	48,922	51,069
Other revenues from operations:
Merchant discount and credit card fees	3,381	2,208
Other	34,088	30,233
Total other income	663,758	626,306
ASU 2014-09 [Member] \| All Other [Member] \| Service Charges on Deposit Accounts [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	5,753	6,137
ASU 2014-09 [Member] \| All Other [Member] \| Trust Income [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	$ 571,614	$ 536,659

Stock-Based Compensation Plans - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2014
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	$ 76	$ 66	$ 61
Recognized income tax benefits related to stock-based compensation	$ 19	$ 24	$ 35
Shares under equity incentive compensation plan for future grant	3,742,478	2,833,428
Stock Options Outstanding, Granted	164,244	116,852
Directors Stock Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares issuable under deferred compensation plans	5,043	6,271
Shares issued in connection with deferred compensation plans	282,532
Deferred Bonus Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares issuable under deferred compensation plans	16,491	18,292
Stock Purchase Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares under equity incentive compensation plan for future grant	2,310,751
Shares issued	71,676	58,167	66,504
Cash received from exercise of stock options	$ 11	$ 10	$ 10
Restricted Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period	3 years	3 years	3 years	4 years
Shares issued	0	0	181,939
Unrecognized compensation cost expected to be recognized over a weighted-average period (in years)	1 year
Restricted Stock Awards [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted-average grant date fair value			$ 30
Restricted Stock Units (RSUs) [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares issued	448,487	348,512	235,983
Weighted-average grant date fair value	$ 74	$ 66	$ 38
Unrecognized compensation cost related to non-vested awards	$ 22
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 1 day
Cash realized from exercise of stock options	$ 9	60	72
Tax benefits realized from exercise of stock options	1	3	10
Intrinsic value of stock options exercised	$ 3	$ 16	$ 31

Stock-Based Compensation Plans - Summary of Restricted Stock and Restricted Stock Unit Activity (Detail)	12 Months Ended
	Dec. 31, 2019 $ / 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	556,875
Restricted Stock Outstanding, Granted \| shares	448,487
Restricted Stock Outstanding, Vested \| shares	(298,243)
Restricted Stock Outstanding, Cancelled \| shares	(15,892)
Restricted Stock Outstanding, Unvested, Ending balance \| shares	691,227
Weighted-Average Grant Price, Unvested, Beginning balance \| $ / shares	$ 170.07
Weighted-Average Grant Price, Granted \| $ / shares	164.63
Weighted-Average Grant Price, Vested \| $ / shares	157.90
Weighted-Average Grant Price, Cancelled \| $ / shares	173.48
Weighted-Average Grant Price, Unvested, Ending balance \| $ / shares	$ 171.72
Restricted Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Restricted Stock Outstanding, Unvested, Beginning balance \| shares	179,439
Restricted Stock Outstanding, Vested \| shares	(113,894)
Restricted Stock Outstanding, Cancelled \| shares	(1,954)
Restricted Stock Outstanding, Unvested, Ending balance \| shares	63,591
Weighted-Average Grant Price, Unvested, Beginning balance \| $ / shares	$ 144.18
Weighted-Average Grant Price, Vested \| $ / shares	133.69
Weighted-Average Grant Price, Cancelled \| $ / shares	161.42
Weighted-Average Grant Price, Unvested, Ending balance \| $ / shares	$ 162.45

Stock-Based Compensation Plans - Summary of Stock Option Activity (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock Options Outstanding, Beginning balance	220,591
Stock Options Outstanding, Granted	164,244	116,852
Stock Options Outstanding, Exercised	(76,181)
Stock Options Outstanding, Expired	(3,202)
Stock Options Outstanding, Ending balance	305,452	220,591
Stock Options Outstanding, Exercisable	66,076
Weighted-Average Exercise Price, Outstanding, Beginning balance	$ 157.98
Weighted-Average Exercise Price, Granted	164.54
Weighted-Average Exercise Price, Exercised	122.55
Weighted-Average Exercise Price, Expired	176.41
Weighted-Average Exercise Price, Outstanding, Ending balance	170.15	$ 157.98
Weighted-Average Exercise Price, Exercisable	$ 159.96
Weighted-Average Life (In Years), Outstanding, Ending balance	8 years
Weighted-Average Life (In Years), Exercisable	5 years 1 month 6 days
Aggregate Intrinsic Value, Outstanding, Ending balance	$ 2,301
Aggregate Intrinsic Value, Exercisable	$ 1,454

Pension Plans and Other Postretirement Benefits - Net Periodic Benefit Cost for Defined Benefit Plans (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 17,294	$ 20,346	$ 20,193
Interest cost on benefit obligation	81,579	74,704	79,270
Expected return on plan assets	(122,139)	(123,127)	(108,524)
Amortization of prior service cost	557	557	557
Recognized net actuarial (gain) loss	21,992	43,793	29,263
Net periodic pension cost (benefit)	(717)	16,273	20,759
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	859	938	1,172
Interest cost on benefit obligation	2,344	2,293	3,716
Amortization of prior service cost	(4,730)	(4,729)	(1,359)
Recognized net actuarial (gain) loss	(1,247)	(826)	(988)
Net periodic pension cost (benefit)	$ (2,774)	$ (2,324)	$ 2,541

Pension Plans and Other Postretirement Benefits - Data Relating to Funding Position of Defined Benefit Plans (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Change in plan assets:
Fair value of plan assets at beginning of year	$ 1,831,773,000
Employer contributions	0	$ 0	$ 200,000
Fair value of plan assets at end of year	2,035,878,000	1,831,773,000
Pension Benefits [Member]
Change in benefit obligation:
Benefit obligation at beginning of year	1,949,613,000	2,188,736,000
Service cost	17,294,000	20,346,000	20,193,000
Interest cost	81,579,000	74,704,000	79,270,000
Actuarial (gain) loss	298,713,000	(228,897,000)
Benefits paid	(99,870,000)	(105,276,000)
Benefit obligation at end of year	2,247,329,000	1,949,613,000	2,188,736,000
Change in plan assets:
Fair value of plan assets at beginning of year	1,833,833,000	2,014,891,000
Actual return on plan assets	293,546,000	(90,657,000)
Employer contributions	10,431,000	14,875,000
Benefits paid	(99,870,000)	(105,276,000)
Fair value of plan assets at end of year	2,037,940,000	1,833,833,000	2,014,891,000
Funded status	(209,389,000)	(115,780,000)
Accrued liabilities recognized in the consolidated balance sheet	(209,389,000)	(115,780,000)
Net loss (gain)	507,029,000	401,716,000
Net prior service cost (credit)	1,834,000	2,391,000
Pre-tax adjustment to AOCI	508,863,000	404,107,000
Taxes	(133,779,000)	(106,240,000)
Net adjustment to AOCI	375,084,000	297,867,000
Other Postretirement Benefits [Member]
Change in benefit obligation:
Benefit obligation at beginning of year	59,991,000	68,637,000
Service cost	859,000	938,000	1,172,000
Interest cost	2,344,000	2,293,000	3,716,000
Plan participants’ contributions	2,749,000	2,974,000
Actuarial (gain) loss	(687,000)	(4,758,000)
Medicare Part D reimbursement	370,000	508,000
Benefits paid	(9,134,000)	(10,601,000)
Benefit obligation at end of year	56,492,000	59,991,000	$ 68,637,000
Change in plan assets:
Employer contributions	6,015,000	7,119,000
Plan participants’ contributions	2,749,000	2,974,000
Medicare Part D reimbursement	370,000	508,000
Benefits paid	(9,134,000)	(10,601,000)
Funded status	(56,492,000)	(59,991,000)
Accrued liabilities recognized in the consolidated balance sheet	(56,492,000)	(59,991,000)
Net loss (gain)	(17,308,000)	(17,868,000)
Net prior service cost (credit)	(27,007,000)	(31,737,000)
Pre-tax adjustment to AOCI	(44,315,000)	(49,605,000)
Taxes	11,650,000	13,041,000
Net adjustment to AOCI	$ (32,665,000)	$ (36,564,000)

Pension Plans and Other Postretirement Benefits - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Minimum pension liability	$ 465,000,000
Minimum pension liability adjustment net of tax	$ 342,000,000
Increase in minimum liability adjustment		$ 110,000,000
Discount rate	3.25%	4.25%
Defined contribution pension and retirement savings plans total expense	$ 32,000,000	$ 29,000,000	$ 30,000,000
Assumptions used calculating net periodic benefit sensitivity rate increase decrease discount rate	0.25%
Effect of 25 basis point increase in rate of return on pension expense	$ 5,000,000
Effect of 25 basis point decrease in rate of return on pension expense	8,000,000
Effect of 25 basis point decrease in discount rate on benefit obligation	75,000,000
Effect of 25 basis point increase in discount rate on benefit obligation	$ 79,000,000
Annual rate of increase in health care cost assumed for next fiscal year	6.25%
Defined Benefit Plan, ultimate health care cost trend rate	5.00%
Period for decreasing the annual rate	over nine years
Defined benefit pension plans	$ 439,000,000
Percentage of total assets	22.00%
Defined benefit plan fair value of plan assets	$ 2,035,878,000	1,831,773,000
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%
Employer contributions	$ 0	0	200,000
Percentage of eligible employees contribution for Retirement Savings Plan	50.00%
Percentage of employer matching contribution to employee's contribution	75.00%
Maximum employer contribution on Employee's qualified contribution	4.50%
Qualified defined contribution plans expense during the period	$ 48,000,000	43,000,000	38,000,000
Equity Securities [Member] \| Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target allocations for plan assets	25.00%
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	$ 439,185,000	361,178,000
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	$ 148,603,000	$ 125,299,000
Percentage of common stock in total plan assets	7.00%	7.00%
Supplemental Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	$ 154,000,000	$ 143,000,000
Accumulated benefit obligation	154,000,000	143,000,000
Employer contributions	10,000,000	15,000,000
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	2,247,329,000	1,949,613,000	2,188,736,000
Accumulated benefit obligation	2,200,000,000	$ 1,900,000,000
Minimum pension liability	$ 509,000,000
Discount rate	3.25%	4.25%
Defined benefit plan fair value of plan assets	$ 2,037,940,000	$ 1,833,833,000	2,014,891,000
Employer contributions	10,431,000	14,875,000
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	56,492,000	$ 59,991,000	$ 68,637,000
Minimum pension liability	$ 44,000,000
Discount rate	3.25%	4.25%
Employer contributions	$ 6,015,000	$ 7,119,000

Pension Plans and Other Postretirement Benefits - Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Net loss (gain)	$ 126,618	$ (19,871)
Amortization of prior service (cost) credit	4,173	4,172	$ 802
Amortization of actuarial (loss) gain	(20,745)	42,967	$ (28,275)
Total recognized in other comprehensive income, pre-tax	110,046	58,666
Pension Benefits [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Net loss (gain)	127,305	(15,113)
Amortization of prior service (cost) credit	(557)	(557)
Amortization of actuarial (loss) gain	(21,992)	43,793
Total recognized in other comprehensive income, pre-tax	104,756	59,463
Other Postretirement Benefits [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Net loss (gain)	(687)	(4,758)
Amortization of prior service (cost) credit	4,730	4,729
Amortization of actuarial (loss) gain	1,247	(826)
Total recognized in other comprehensive income, pre-tax	$ 5,290	$ (797)

Pension Plans and Other Postretirement Benefits - Assumed Weighted-Average Rates Used to Determine Net Benefit Expense (Detail)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Pension Benefits [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Discount rate	4.25%	3.50%	4.00%
Long-term rate of return on plan assets	6.50%	6.50%	6.50%
Rate of increase in future compensation levels	4.31%	4.33%	4.39%
Other Postretirement Benefits [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Discount rate	4.25%	3.50%	4.00%

Pension Plans and Other Postretirement Benefits - Effects on One-Percentage Point Change in Assumed Health Care Cost Trend Rates (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($)
Compensation And Retirement Disclosure [Abstract]
Service and interest cost	$ 49
Accumulated postretirement benefit obligation	834
Service and interest cost	(45)
Accumulated postretirement benefit obligation	$ (747)

Pension Plans and Other Postretirement Benefits - Changes in Level 3 Pension Plan Assets Measured at Fair Value on Recurring Basis (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($)
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of plan assets at beginning of year	$ 1,831,773
Fair value of plan assets at end of year	2,035,878
Significant Unobservable Inputs (Level 3) [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of plan assets at beginning of year	158,632
Fair value of plan assets at end of year	232,237
Other 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	9,016
Purchase(Sales)	7,623
Total Realized/Unrealized Gains (Losses)	1,327
Fair value of plan assets at end of year	17,966
Other Private Equity [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	63,699
Purchase(Sales)	9,531
Total Realized/Unrealized Gains (Losses)	14,736
Fair value of plan assets at end of year	87,966
Other 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	75,502
Purchase(Sales)	27,000
Total Realized/Unrealized Gains (Losses)	13,276
Fair value of plan assets at end of year	115,778
Guaranteed Deposit Fund [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of plan assets at beginning of year	10,415
Fair value of plan assets at end of year	10,527
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	10,415
Total Realized/Unrealized Gains (Losses)	112
Fair value of plan assets at end of year	10,527
Other Securities [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of plan assets at beginning of year	361,178
Fair value of plan assets at end of year	439,185
Other 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	158,632
Purchase(Sales)	44,154
Total Realized/Unrealized Gains (Losses)	29,451
Fair value of plan assets at end of year	$ 232,237

Pension Plans and Other Postretirement Benefits - Defined Benefit Plan Estimated Future Benefit Payments (Detail) $ in Thousands	Dec. 31, 2019 USD ($)
Pension Benefits [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
2020	$ 100,800
2021	104,385
2022	107,368
2023	111,990
2024	115,962
2025 through 2029	619,663
Other Postretirement Benefits [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
2020	6,622
2021	4,036
2022	3,972
2023	3,904
2024	3,829
2025 through 2029	$ 17,919

Income Taxes - Components of Income Tax Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Current
Federal	$ 359,668	$ 408,428	$ 363,043
State and local	132,696	113,706	94,714
Total current	492,364	522,134	457,757
Deferred
Federal	40,769	(12,780)	367,308
State and local	16,779	28,637	33,482
Total deferred	57,548	15,857	400,790
Amortization of investments in qualified affordable housing projects	68,200	52,169	57,009
Income taxes	$ 618,112	$ 590,160	$ 915,556

Income Taxes - Additional Information (Detail)	3 Months Ended	12 Months Ended
Income Taxes - Additional Information (Detail)	Dec. 31, 2017 USD ($)	Dec. 31, 2019 USD ($) State	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Income Tax Disclosure [Abstract]
Tax bad debt reserve		$ 137,000,000
Income taxes attributable to gains or losses on bank investment securities		$ 5,000,000	$ (2,000,000)	$ 7,000,000
Alternative minimum tax expense recognized for gains or losses on bank investment securities				$ 0
Federal income tax rate		21.00%	21.00%	35.00%
Incremental income tax expense related to Tax Act	$ 85,000,000
Reduction in income tax expense due to reduction of federal tax rate			$ 15,000,000
Number of state and local jurisdictions where company files income tax returns \| State		40

Income Taxes - Schedule of Income Taxes Expenses Benefit Reconciliation (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income taxes at statutory federal income tax rate	$ 534,925	$ 526,730	$ 813,352
Increase (decrease) in taxes:
Tax-exempt income	(27,319)	(26,186)	(40,778)
State and local income taxes, net of federal income tax effect	118,085	112,451	83,327
Qualified affordable housing project federal tax credits, net	(15,324)	(12,240)	(16,015)
Initial impact of enactment of Tax Act			85,431
Other	7,745	(10,595)	(9,761)
Income taxes	$ 618,112	$ 590,160	$ 915,556

Income Taxes - Deferred Tax Assets (Liabilities) (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Losses on loans and other assets	$ 309,523	$ 322,818	$ 345,609
Operating lease liabilities	128,178
Retirement benefits	55,048	30,057	45,322
Postretirement and other employee benefits	24,023	23,563	26,009
Incentive and other compensation plans	26,861	24,796	25,050
Interest on loans			37,900
Stock-based compensation	27,912	26,759	26,676
Unrealized losses		52,580
Losses on cash flow hedges		1,861	4,033
Other	69,863	43,880	66,247
Gross deferred tax assets	641,408	526,314	576,846
Right of use assets and other leasing transactions	(326,626)	(186,787)	(181,159)
Unrealized gains	(13,322)		(94,285)
Capitalized servicing rights	(56,649)	(54,894)	(51,781)
Depreciation and amortization	(66,925)	(61,881)	(52,733)
Interest on loans	(23,552)	(18,920)
Gains on cash flow hedges	(36,845)
Other	(40,472)	(30,211)	(25,632)
Gross deferred tax liabilities	(564,391)	(352,693)	(405,590)
Net deferred tax asset	$ 77,017	$ 173,621	$ 171,256

Income Taxes - Reconciliation of Beginning and Ending Amount of Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Federal, State and Local Tax [Member]
Reconciliation Of Unrecognized Tax Benefits [Line Items]
Beginning Balance	$ 56,274	$ 45,432	$ 35,889
Increases as a result of tax positions taken during the period	6,996	13,426	13,019
Increases as a result of tax positions taken in prior years	3,265
Decreases as a result of settlements with taxing authorities		(664)	(332)
Decreases as a result of tax positions taken in prior years	(7,566)	(1,920)	(3,144)
Ending Balance	58,969	56,274	45,432
Accrued Interest [Member]
Reconciliation Of Unrecognized Tax Benefits [Line Items]
Beginning Balance	6,629	5,651	7,915
Increases as a result of tax positions taken in prior years	3,255	1,969	1,379
Decreases as a result of settlements with taxing authorities		(289)	(168)
Decreases as a result of tax positions taken in prior years	(2,685)	(702)	(3,475)
Ending Balance	7,199	6,629	5,651
Unrecognized Income Tax Benefits [Member]
Reconciliation Of Unrecognized Tax Benefits [Line Items]
Beginning Balance	62,903	51,083	43,804
Increases as a result of tax positions taken during the period	6,996	13,426	13,019
Increases as a result of tax positions taken in prior years	6,520	1,969	1,379
Decreases as a result of settlements with taxing authorities		(953)	(500)
Decreases as a result of tax positions taken in prior years	(10,251)	(2,622)	(6,619)
Ending Balance	66,168	$ 62,903	$ 51,083
Less: Federal, state and local income tax benefits	(13,208)
Net unrecognized tax benefits that, if recognized, would impact the effective income tax rate	$ 52,960

Earnings Per Common Share - Computations of Basic Earnings Per Common Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income available to common shareholders:
Net income	$ 1,929,149	$ 1,918,080	$ 1,408,306
Less: Preferred stock dividends	(69,441)	(72,521)	(72,734)
Net income available to common equity	1,859,708	1,845,559	1,335,572
Less: Income attributable to unvested stock-based compensation awards	(10,199)	(9,531)	(8,069)
Net income available to common shareholders	$ 1,849,509	$ 1,836,028	$ 1,327,503
Weighted-average shares outstanding:
Common shares outstanding (including common stock issuable) and unvested stock-based compensation awards	135,169	144,740	153,092
Less: Unvested stock-based compensation awards	(741)	(748)	(933)
Weighted-average shares outstanding	134,428	143,992	152,159
Basic earnings per common share	$ 13.76	$ 12.75	$ 8.72

Earnings Per Common Share - Computations of Diluted Earnings Per Common Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Earnings Per Share [Abstract]
Net income available to common equity	$ 1,859,708	$ 1,845,559	$ 1,335,572
Less: Income attributable to unvested stock-based compensation awards	(10,197)	(9,524)	(8,055)
Net income available to common shareholders	$ 1,849,511	$ 1,836,035	$ 1,327,517
Adjusted weighted-average shares outstanding:
Common and unvested stock-based compensation awards	135,169	144,740	153,092
Less: Unvested stock-based compensation awards	(741)	(748)	(933)
Plus: Incremental shares from assumed conversion of stock-based compensation awards and warrants to purchase common stock	34	159	392
Adjusted weighted-average shares outstanding	134,462	144,151	152,551
Diluted earnings per common share	$ 13.75	$ 12.74	$ 8.70

Comprehensive Income - Components of Other Comprehensive Income (Loss) and Amounts Reclassified from Accumulated Other Comprehensive Income (Loss) to Net Income (Detail) - USD ($)
$ in Thousands

12 Months Ended

Dec. 31, 2019

Dec. 31, 2018

Dec. 31, 2017

Accumulated Other Comprehensive Income (Loss) [Line Items]

Beginning balance, before tax

$ (569,328)

$ (493,290)

$ (485,245)

Unrealized holding gains (losses), net, before tax

247,411

(121,589)

(15,005)

Foreign currency translation adjustment, before tax

1,381

(2,817)

4,447

Unrealized losses on cash flow hedges, before tax

160,373

(4,965)

(12,291)

Current year benefit plans gains, before tax

(126,618)

19,871

9,276

Total other comprehensive income (loss), before tax

282,547

(109,500)

(13,573)

Amortization of unrealized holding losses on held-to-maturity ("HTM") securities, before tax

3,394

4,252

3,387

Gains realized in net income, before tax

(18)

(21,279)

Accretion of net gain (losses) on terminated cash flow hedges, before tax

(136)

(111)

(137)

Net yield adjustment from cash flow hedges currently in effect, before tax

(13,011)

13,339

(3,916)

Amortization of prior service credit, before tax

(4,173)

(4,172)

(802)

Amortization of actuarial losses, before tax

20,745

(42,967)

28,275

Total other comprehensive income (loss), before tax

289,369

(53,243)

(8,045)

Reclassification of income tax effects to retained earnings

(64,029)

Ending balance, before tax

(279,959)

(569,328)

(493,290)

Cumulative effect of change in accounting principles — equity securities, before tax

^[1]

(22,795)

Amortization of actuarial (loss) gain

(20,745)

42,967

(28,275)

Beginning balance, tax

149,247

129,476

190,609

Unrealized holding gains (losses), net, tax

(65,009)

31,946

7,269

Foreign currency translation adjustment, tax

(290)

592

(2,206)

Unrealized losses on cash flow hedges, tax

(42,163)

1,306

4,837

Current year benefit plans gains, tax

33,287

(5,224)

(3,650)

Total other comprehensive income (loss), tax

(74,175)

28,620

6,250

Amortization of unrealized holding losses on held-to-maturity ('HTM') securities, tax

(892)

(1,118)

(1,333)

Gains realized in net income, tax

(1)

7,195

Accretion of net gain on terminated cash flow hedges, tax

Net yield adjustment from cash flow hedges currently in effect, tax

3,421

(3,507)

1,541

Amortization of prior service credit, tax

1,097

315

Amortization of actuarial losses, tax

(5,454)

(11,296)

(11,126)

Total other comprehensive income (loss), tax

(75,968)

13,829

2,896

Reclassification of income tax effects to retained earnings, tax

(64,029)

Ending balance, tax

73,279

149,247

129,476

Cumulative effect of change in accounting principles — equity securities, tax

^[1]

5,942

Beginning balance, net of tax

(420,081)

(363,814)

(294,636)

Unrealized holding gains (losses), net of tax

182,402

(89,643)

(7,736)

Foreign currency translation adjustments

1,091

(2,225)

2,241

Unrealized losses on cash flow hedges, net of tax

118,210

(3,659)

(7,454)

Current year benefit plans gains, net of tax

(93,331)

14,647

5,626

Total other comprehensive income (loss) before reclassifications, net of tax

208,372

(80,880)

(7,323)

Amortization of unrealized holding losses on held-to-maturity ('HTM') securities, net of tax

2,502

3,134

2,054

Gains realized in net income, net of tax

(14)

(14,084)

Accretion of net gain on terminated cash flow hedges, net of tax

(100)

(82)

(83)

Net yield adjustment from cash flow hedges currently in effect, net of tax

(9,590)

9,832

(2,375)

Amortization of prior service credit, net of tax

(3,076)

(3,075)

(487)

Amortization of actuarial losses, net of tax

15,291

31,671

17,149

Total other comprehensive income (loss)

213,401

(39,414)

(5,149)

Ending balance, net of tax

(206,680)

(420,081)

(363,814)

Cumulative effect of change inaccounting principle — equity securities

^[1]

(16,853)

Reclassification of income tax effects to retained earnings, before tax

(64,029)

Gains realized in net income, net of tax

(14)

(14,084)

Investment Securities [Member]

Accumulated Other Comprehensive Income (Loss) [Line Items]

Beginning balance, before tax

(200,107)

(59,957)

Unrealized holding gains (losses), net, before tax

247,411

(121,589)

Total other comprehensive income (loss), before tax

247,411

(121,589)

Amortization of unrealized holding losses on held-to-maturity ("HTM") securities, before tax

3,394

4,252

Gains realized in net income, before tax

(18)

Total other comprehensive income (loss), before tax

250,808

(117,355)

Reclassification of income tax effects to retained earnings

8,065

Ending balance, before tax

50,701

(200,107)

(59,957)

Cumulative effect of change in accounting principles — equity securities, before tax

^[1]

(22,795)

Total other comprehensive income (loss)

184,906

(86,523)

(19,766)

Cumulative effect of change inaccounting principle — equity securities

(16,853)

Reclassification of income tax effects to retained earnings, before tax

8,065

Defined Benefit Plans [Member]

Accumulated Other Comprehensive Income (Loss) [Line Items]

Beginning balance, before tax

(354,502)

(413,168)

(449,917)

Current year benefit plans gains, before tax

(126,618)

19,871

9,276

Total other comprehensive income (loss), before tax

(126,618)

19,871

9,276

Amortization of prior service credit, before tax

(4,173)

(4,172)

(802)

Amortization of actuarial losses, before tax

20,745

(42,967)

28,275

Total other comprehensive income (loss), before tax

(110,046)

58,666

36,749

Reclassification of income tax effects to retained earnings

53,960

Ending balance, before tax

(464,548)

(354,502)

(413,168)

Amortization of actuarial (loss) gain

(20,745)

42,967

(28,275)

Total other comprehensive income (loss)

(81,116)

43,243

22,288

Reclassification of income tax effects to retained earnings, before tax

53,960

Other [Member]

Accumulated Other Comprehensive Income (Loss) [Line Items]

Beginning balance, before tax

(14,719)

(20,165)

(8,268)

Foreign currency translation adjustment, before tax

1,381

(2,817)

4,447

Unrealized losses on cash flow hedges, before tax

160,373

(4,965)

(12,291)

Total other comprehensive income (loss), before tax

161,754

(7,782)

(7,844)

Accretion of net gain (losses) on terminated cash flow hedges, before tax

(136)

(111)

(137)

Net yield adjustment from cash flow hedges currently in effect, before tax

(13,011)

13,339

(3,916)

Total other comprehensive income (loss), before tax

148,607

5,446

(11,897)

Ending balance, before tax

$ 133,888

(14,719)

(20,165)

Investment Securities With OTTI [Member]

Accumulated Other Comprehensive Income (Loss) [Line Items]

Beginning balance, before tax

19,628

46,725

Unrealized holding gains (losses), net, before tax

(8,746)

Total other comprehensive income (loss), before tax

(8,746)

Gains realized in net income, before tax

(18,351)

Total other comprehensive income (loss), before tax

(27,097)

Ending balance, before tax

19,628

Investment Securities All Other [Member]

Accumulated Other Comprehensive Income (Loss) [Line Items]

Beginning balance, before tax

$ (79,585)

(73,785)

Unrealized holding gains (losses), net, before tax

(6,259)

Total other comprehensive income (loss), before tax

(6,259)

Amortization of unrealized holding losses on held-to-maturity ("HTM") securities, before tax

3,387

Gains realized in net income, before tax

(2,928)

Total other comprehensive income (loss), before tax

(5,800)

Ending balance, before tax

$ (79,585)

[1]

Comprehensive Income - Accumulated Other Comprehensive Income (Loss), Net (Detail) - USD ($)
$ in Thousands

12 Months Ended

Dec. 31, 2019

Dec. 31, 2018

Dec. 31, 2017

Accumulated Other Comprehensive Income (Loss) [Line Items]

Beginning balance

$ 15,460,191

$ 16,250,819

$ 16,486,622

Cumulative effect of change inaccounting principle — equity securities

^[1]

(16,853)

Net gain (loss) during period

213,401

(39,414)

(5,149)

Reclassification of income tax effects to retained earnings

64,029

Ending balance

15,716,649

15,460,191

16,250,819

Investment Securities [Member]

Accumulated Other Comprehensive Income (Loss) [Line Items]

Beginning balance

(147,526)

(44,150)

(16,319)

Cumulative effect of change inaccounting principle — equity securities

(16,853)

Net gain (loss) during period

184,906

(86,523)

(19,766)

Reclassification of income tax effects to retained earnings

(8,065)

Ending balance

37,380

(147,526)

(44,150)

Defined Benefit Plans [Member]

Accumulated Other Comprehensive Income (Loss) [Line Items]

Beginning balance

(261,303)

(304,546)

(272,874)

Net gain (loss) during period

(81,116)

43,243

22,288

Reclassification of income tax effects to retained earnings

(53,960)

Ending balance

(342,419)

(261,303)

(304,546)

Accumulated Other Adjustment [Member]

Accumulated Other Comprehensive Income (Loss) [Line Items]

Beginning balance

(11,252)

(15,118)

(5,443)

Net gain (loss) during period

109,611

3,866

(7,671)

Reclassification of income tax effects to retained earnings

(2,004)

Ending balance

98,359

(11,252)

(15,118)

Accumulated Other Comprehensive Income (Loss), Net [Member]

Accumulated Other Comprehensive Income (Loss) [Line Items]

Beginning balance

(420,081)

(363,814)

(294,636)

Cumulative effect of change inaccounting principle — equity securities

(16,853)

Net gain (loss) during period

213,401

(39,414)

(5,149)

Reclassification of income tax effects to retained earnings

(64,029)

Ending balance

$ (206,680)

$ (420,081)

$ (363,814)

[1]

Other Income and Other Expense - Other Income and Other Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Other income:
Credit-related fee income	$ 86,792	$ 82,614	$ 77,580
Other expense:
Professional services	330,900	312,998	289,862
Amortization of capitalized mortgage servicing rights	$ 71,888	49,619	$ 56,172
Wilmington Trust Corporation [Member]
Other expense:
Accrual for Wilmington Trust Corporation legal-related matters		$ 135,000

International Activities - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
International Activities [Line Items]
Revenues from international trust-related services	$ 32,000	$ 29,000	$ 24,000
Loans to foreign borrowers	89,871,798	87,447,033
Deposits at foreign office	1,684,044	811,906
Cayman Islands [Member]
International Activities [Line Items]
Deposits at foreign office	1,680,000	812,000
Canada [Member]
International Activities [Line Items]
Deposits at foreign office	23,000	22,000
Geographic Distribution, Foreign [Member]
International Activities [Line Items]
Loans to foreign borrowers	$ 186,000	$ 172,000
Geographic Concentration Risk [Member] \| Assets, Total [Member]
International Activities [Line Items]
Concentration risk percentage	1.00%
Geographic Concentration Risk [Member] \| Sales Revenue, Net [Member]
International Activities [Line Items]
Concentration risk percentage	1.00%

Derivative Financial Instruments - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Derivative [Line Items]
Notional amounts of derivative contracts entered into for trading account purposes	$ 57,550,000,000	$ 19,850,000,000
Net unrealized pre-tax gains related to hedged loans held for sale, commitments to originate loans for sale and commitments to sell loans	18,000,000	18,000,000
Aggregate fair value of derivative financial instruments in a liability position	51,000,000	21,000,000
Aggregate fair value of derivative financial instruments in asset position	6,000,000	18,000,000
Collateral relating to net asset positions	5,000,000	16,000,000
Counterparties [Member]
Derivative [Line Items]
Post collateral requirements relating to positions	50,000,000	18,000,000
Clearinghouse Credit Facilities [Member]
Derivative [Line Items]
Amount of initial margin posted	84,000,000	65,000,000
Interest Rate Swap Agreements [Member]
Derivative [Line Items]
Increase decrease in net interest income due to interest rate swap agreements	(2,000,000)	25,000,000	$ 25,000,000
Notional amounts of derivative contracts entered into for trading account purposes	57,550,000,000
Interest Rate Contracts [Member]
Derivative [Line Items]
Notional amounts of derivative contracts entered into for trading account purposes	48,600,000,000	42,900,000,000
Foreign Currency and Other Option and Futures Contracts [Member]
Derivative [Line Items]
Notional amounts of derivative contracts entered into for trading account purposes	1,200,000	$ 763,000,000
Credit Risk Derivative [Member]
Derivative [Line Items]
Fair value of additional collateral to be posted for derivative financial instruments	$ 0

Derivative Financial Instruments - Information about Interest Rate Swap Agreements (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Derivative [Line Items]
Notional Amount	$ 57,550,000,000	$ 19,850,000,000
Average Maturity (in years)	1 year 6 months	1 year 8 months 12 days
Estimated Fair Value Gain (Loss)	$ (1,762,000)	$ 5,530,000
Interest Payments On Variable Rate Commercial Real Estate Loans [Member] \| Cash Flow Hedges [Member]
Derivative [Line Items]
Notional Amount	$ 53,750,000,000	$ 15,400,000,000
Average Maturity (in years)	1 year 4 months 24 days	1 year 3 months 18 days
Weighted-Average Rate, Fixed	2.44%	1.52%
Weighted-Average Rate, Variable	1.73%	2.35%
Estimated Fair Value Gain (Loss)	$ (1,195,000)	$ 1,311,000
Fixed Rate Long-Term Borrowings [Member] \| Fair Value Hedges [Member]
Derivative [Line Items]
Notional Amount	$ 3,800,000,000	$ 4,450,000,000
Average Maturity (in years)	2 years 2 months 12 days	2 years 9 months 18 days
Weighted-Average Rate, Fixed	2.51%	2.47%
Weighted-Average Rate, Variable	2.27%	3.02%
Estimated Fair Value Gain (Loss)	$ (567,000)	$ 4,219,000

Derivative Financial Instruments - Notional Amount of Interest Rate Swap Agreements Outstanding Maturity (Detail) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Total	$ 57,550,000,000	$ 19,850,000,000
Interest Rate Swap Agreements [Member]
Derivative Instruments And Hedging Activities Disclosures [Line Items]
2020	12,200,000,000
2021	28,350,000,000
2022	16,000,000,000
2023	500,000,000
2027	500,000,000
Total	$ 57,550,000,000

Derivative Financial Instruments - Information about Fair Values of Derivative Instruments in Consolidated Balance Sheet (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value	$ 427,267	$ 148,862
Liability Derivatives, Fair Value	87,091	190,686
Derivatives Not Designated and Qualifying as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value	425,840	142,242
Liability Derivatives, Fair Value	84,676	184,252
Fair Value Hedges [Member] \| Derivatives Designated and Qualifying as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value	1,427	6,620
Liability Derivatives, Fair Value	2,415	6,434
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	232	5,530
Liability Derivatives, Fair Value	1,994
Commitments to Sell Real Estate Loans [Member] \| Derivatives Not Designated and Qualifying as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value	3,074	3,702
Liability Derivatives, Fair Value	3,548	4,535
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	1,195	1,090
Liability Derivatives, Fair Value	421	6,434
Mortgage-Related Commitments to Originate Real Estate Loans for Sale [Member] \| Derivatives Not Designated and Qualifying as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value	11,965	9,304
Liability Derivatives, Fair Value	1,225	1,592
Interest Rate Contracts [Member] \| Derivatives Not Designated and Qualifying as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value	398,295	118,687
Liability Derivatives, Fair Value	68,103	169,255
Foreign Exchange and Other Option and Futures Contracts [Member] \| Derivatives Not Designated and Qualifying as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value	12,506	10,549
Liability Derivatives, Fair Value	$ 11,800	$ 8,870

Derivative Financial Instruments - Information about Fair Values of Derivative Instruments in Consolidated Statement of Income (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives not designated as hedging instruments, Derivatives	$ 33,212	$ 13,922	$ 12,219
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	95,006	(10,006)	(52,392)
Derivatives in fair value hedging relationships, Hedged item	(94,742)	10,969	51,628
Interest Rate Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives not designated as hedging instruments, Derivatives	24,701	4,506	5,398
Foreign Exchange and Other Option and Futures Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives not designated as hedging instruments, Derivatives	$ 8,511	$ 9,416	$ 6,821

Variable Interest Entities - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Loss on securitization of assets	$ 0	$ 0	$ 0
Other assets for its "investment" in the common securities recognized by the company of various trusts	23,000,000	23,000,000
Total assets of partnerships in which the company invested	119,872,757,000	120,097,403,000
Investment in partnership carrying amount	748,000,000	523,000,000
Unfunded commitments includes carrrying amount of its investments	414,000,000	280,000,000
Maximum exposure to loss of investments in real estate partnerships	984,000,000
Variable Interest Entity Primary Beneficiary [Member]
Total assets of partnerships in which the company invested	$ 1,500,000,000	$ 1,100,000,000

- Definition

A gain (loss) realized on a transfer, accounted for as a sale, of all or a portion of financial assets in which the transferor surrenders control and receives consideration other than a beneficial interest in the assets transferred. Reflects the amount of sales proceeds in excess of, or deficient from, the sum of the carrying amounts of transferred financial assets plus transaction costs.

+ References + Details

Fair Value Measurements - Assets and Liabilities Measured at Estimated Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities	$ 6,318,776	$ 8,682,509
U.S. Treasury and Federal Agencies [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities	9,767	1,336,931
Obligations of States and Political Subdivisions [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities	775	1,659
Government Issued or Guaranteed [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities	6,180,940	7,216,991
Other Debt Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities	127,278	126,906
Fair Value Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Trading account assets	470,129	185,584
Investment securities	6,318,776	8,682,509
Equity securities	140,041	93,917
Real estate loans held for sale	442,079	551,697
Other assets	16,466	19,626
Total assets	7,387,491	9,533,333
Trading account liabilities	79,903	178,125
Other liabilities	7,188	12,561
Total liabilities	87,091	190,686
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 assets	49,040	46,018
Equity securities	100,637	71,989
Total assets	149,677	118,007
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 assets	421,089	139,566
Investment securities	6,318,760	8,682,487
Equity securities	39,404	21,928
Real estate loans held for sale	442,079	551,697
Other assets	4,501	10,322
Total assets	7,225,833	9,406,000
Trading account liabilities	79,903	178,125
Other liabilities	5,963	10,969
Total liabilities	85,866	189,094
Fair Value Measurements, Recurring [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities	16	22
Other assets	11,965	9,304
Total assets	11,981	9,326
Other liabilities	1,225	1,592
Total liabilities	1,225	1,592
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]
Investment securities	9,767	1,336,931
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]
Investment securities	9,767	1,336,931
Fair Value Measurements, Recurring [Member] \| Obligations of States and Political Subdivisions [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities	775	1,659
Fair Value Measurements, Recurring [Member] \| Obligations of States and Political Subdivisions [Member] \| Significant Observable Inputs (Level 2) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities	775	1,659
Fair Value Measurements, Recurring [Member] \| Government Issued or Guaranteed [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities	6,180,940	7,216,991
Fair Value Measurements, Recurring [Member] \| Government Issued or Guaranteed [Member] \| Significant Observable Inputs (Level 2) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities	6,180,940	7,216,991
Fair Value Measurements, Recurring [Member] \| Privately Issued Mortgage-Backed Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities	16	22
Fair Value Measurements, Recurring [Member] \| Privately Issued Mortgage-Backed Securities [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities	16	22
Fair Value Measurements, Recurring [Member] \| Other Debt Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities	127,278	126,906
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]
Investment securities	$ 127,278	$ 126,906

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] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Privately Issued Mortgage-Backed Securities [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning Balance	$ 22	$ 28	$ 44
Total gains realized/unrealized:
Settlements	(6)	(6)	(16)
Ending Balance	16	22	28
Other Assets and Other Liabilities [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning Balance	7,712	8,303	7,325
Total gains realized/unrealized:
Included in earnings	129,398	58,740	77,832
Transfers out of Level 3	(126,370)	(59,331)	(76,854)
Ending Balance	10,740	7,712	8,303
Changes in unrealized gains included in earnings related to assets still held at end of period	$ 11,146	$ 7,386	$ 7,978

Fair Value Measurements - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Measurement Input [Extensible List]	us-gaap:MeasurementInputComparabilityAdjustmentMember
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	85.00%
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	$ 110	$ 83	$ 56
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	305	268	210
Assets taken in foreclosure of defaulted loans measured at fair value on a nonrecurring basis	21	28
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	115	120	145
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	$ 190	$ 148	$ 65

Fair Value Measurements - Quantitative Information Related to Significant Unobservable Inputs (Detail) - Fair Value Measurements, Recurring [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Privately Issued Mortgage-Backed Securities [Member] \| Two Independent Pricing Quotes [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	$ 16	$ 22
Other Assets and Other Liabilities [Member] \| 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	$ 10,740	$ 7,712
Other Assets and Other Liabilities [Member] \| Discounted Cash Flows [Member] \| Minimum [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Commitment expirations	0.00%	0.00%
Other Assets and Other Liabilities [Member] \| Discounted Cash Flows [Member] \| Maximum [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Commitment expirations	99.00%	95.00%
Other Assets and Other Liabilities [Member] \| Discounted Cash Flows [Member] \| Weighted Average [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Commitment expirations	13.00%	13.00%

Fair Value Measurements - Carrying Amounts and Estimated Fair Value for Financial Instrument Assets (Liabilities) (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Financial assets:
Interest-bearing deposits at banks	$ 7,190,154	$ 8,105,197
Federal funds sold	3,500
Investment securities	9,497,251	12,692,813
Loans and leases:
Commercial loans and leases	89,776,328	87,326,591
Allowance for credit losses	(1,051,071)	(1,019,444)	$ (1,017,198)	$ (988,997)
Loans and leases, net	89,871,798	87,447,033
Financial liabilities:
Noninterest-bearing deposits	(32,396,407)	(32,256,668)
Savings and interest-checking deposits	(54,932,162)	(50,963,744)
Time deposits	(5,757,456)	(6,124,254)
Deposits at Cayman Islands office	(1,684,044)	(811,906)
Long-term borrowings	(6,986,186)	(8,444,914)
Carrying Amount [Member]
Financial assets:
Cash and cash equivalents	1,432,805	1,605,439
Interest-bearing deposits at banks	7,190,154	8,105,197
Federal funds sold	3,500
Trading account assets	470,129	185,584
Investment securities	9,497,251	12,692,813
Loans and leases:
Consumer loans	15,386,693	13,970,499
Allowance for credit losses	(1,051,071)	(1,019,444)
Loans and leases, net	89,871,798	87,447,033
Accrued interest receivable	333,142	353,965
Financial liabilities:
Noninterest-bearing deposits	(32,396,407)	(32,256,668)
Savings and interest-checking deposits	(54,932,162)	(50,963,744)
Time deposits	(5,757,456)	(6,124,254)
Deposits at Cayman Islands office	(1,684,044)	(811,906)
Short-term borrowings	(62,363)	(4,398,378)
Long-term borrowings	(6,986,186)	(8,444,914)
Accrued interest payable	(105,374)	(95,274)
Trading account liabilities	(79,903)	(178,125)
Other financial instruments:
Commitments to originate real estate loans for sale	10,740	7,712
Commitments to sell real estate loans	300	(6,177)
Other credit-related commitments	(136,470)	(131,688)
Interest rate swap agreements used for interest rate risk management	(1,762)	5,530
Estimate Fair Value [Member]
Financial assets:
Cash and cash equivalents	1,432,805	1,605,439
Interest-bearing deposits at banks	7,190,154	8,105,197
Federal funds sold	3,500
Trading account assets	470,129	185,584
Investment securities	9,539,540	12,631,656
Loans and leases:
Consumer loans	15,413,262	13,819,545
Loans and leases, net	90,668,624	87,214,035
Accrued interest receivable	333,142	353,965
Financial liabilities:
Noninterest-bearing deposits	(32,396,407)	(32,256,668)
Savings and interest-checking deposits	(54,932,162)	(50,963,744)
Time deposits	(5,829,347)	(6,201,957)
Deposits at Cayman Islands office	(1,684,044)	(811,906)
Short-term borrowings	(62,363)	(4,398,378)
Long-term borrowings	(7,063,165)	(8,385,289)
Accrued interest payable	(105,374)	(95,274)
Trading account liabilities	(79,903)	(178,125)
Other financial instruments:
Commitments to originate real estate loans for sale	10,740	7,712
Commitments to sell real estate loans	300	(6,177)
Other credit-related commitments	(136,470)	(131,688)
Interest rate swap agreements used for interest rate risk management	(1,762)	5,530
Estimate Fair Value [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Financial assets:
Cash and cash equivalents	1,394,984	1,528,302
Trading account assets	49,040	46,018
Investment securities	100,637	71,989
Estimate Fair Value [Member] \| Significant Observable Inputs (Level 2) [Member]
Financial assets:
Cash and cash equivalents	37,821	77,137
Interest-bearing deposits at banks	7,190,154	8,105,197
Federal funds sold	3,500
Trading account assets	421,089	139,566
Investment securities	9,351,793	12,456,467
Loans and leases:
Loans and leases, net	4,019,186	4,267,222
Accrued interest receivable	333,142	353,965
Financial liabilities:
Noninterest-bearing deposits	(32,396,407)	(32,256,668)
Savings and interest-checking deposits	(54,932,162)	(50,963,744)
Time deposits	(5,829,347)	(6,201,957)
Deposits at Cayman Islands office	(1,684,044)	(811,906)
Short-term borrowings	(62,363)	(4,398,378)
Long-term borrowings	(7,063,165)	(8,385,289)
Accrued interest payable	(105,374)	(95,274)
Trading account liabilities	(79,903)	(178,125)
Other financial instruments:
Commitments to sell real estate loans	300	(6,177)
Interest rate swap agreements used for interest rate risk management	(1,762)	5,530
Estimate Fair Value [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Financial assets:
Investment securities	87,110	103,200
Loans and leases:
Consumer loans	15,413,262	13,819,545
Loans and leases, net	86,649,438	82,946,813
Other financial instruments:
Commitments to originate real estate loans for sale	10,740	7,712
Other credit-related commitments	(136,470)	(131,688)
Commercial Loans and Leases [Member] \| Carrying Amount [Member]
Loans and leases:
Commercial loans and leases	23,838,168	22,977,976
Commercial Loans and Leases [Member] \| Estimate Fair Value [Member]
Loans and leases:
Commercial loans and leases	23,510,908	22,587,387
Commercial Loans and Leases [Member] \| Estimate Fair Value [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Loans and leases:
Commercial loans and leases	23,510,908	22,587,387
Commercial [Member] \| Carrying Amount [Member]
Loans and leases:
Commercial loans and leases	35,541,914	34,363,556
Commercial [Member] \| Estimate Fair Value [Member]
Loans and leases:
Commercial loans and leases	35,517,180	33,832,558
Commercial [Member] \| Estimate Fair Value [Member] \| Significant Observable Inputs (Level 2) [Member]
Loans and leases:
Commercial loans and leases	28,338	346,775
Commercial [Member] \| Estimate Fair Value [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Loans and leases:
Commercial loans and leases	35,488,842	33,485,783
Residential Real Estate Loans \| Carrying Amount [Member]
Loans and leases:
Commercial loans and leases	16,156,094	17,154,446
Residential Real Estate Loans \| Estimate Fair Value [Member]
Loans and leases:
Commercial loans and leases	16,227,274	16,974,545
Residential Real Estate Loans \| Estimate Fair Value [Member] \| Significant Observable Inputs (Level 2) [Member]
Loans and leases:
Commercial loans and leases	3,990,848	3,920,447
Residential Real Estate Loans \| Estimate Fair Value [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Loans and leases:
Commercial loans and leases	$ 12,236,426	$ 13,054,098

Commitments and Contingencies - Commitments and Contingent Liabilities Outstanding (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Commitments to extend credit
Home equity lines of credit	$ 5,442,160	$ 5,484,197
Commercial real estate loans to be sold	164,076	229,401
Other commercial real estate	9,029,608	7,556,722
Residential real estate loans to be sold	423,056	245,211
Other residential real estate	448,375	219,351
Commercial and other	16,170,731	14,363,803
Standby letters of credit	2,441,432	2,326,991
Commercial letters of credit	41,059	55,808
Financial guarantees and indemnification contracts	4,108,572	3,529,136
Commitments to sell real estate loans	$ 906,037	$ 940,692

Segment Information - Information about Company's Segments (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Net interest income	$ 4,130,264	$ 4,072,302	$ 3,781,044
Noninterest income	2,061,679	1,856,000	1,851,143
Total income	6,191,943	5,928,302	5,632,187
Provision for credit losses	176,000	132,000	168,000
Amortization of core deposit and other intangible assets	19,490	24,522	31,366
Depreciation and other amortization	180,924	154,483	165,759
Other noninterest expense	3,268,268	3,109,057	2,943,200
Income before taxes	2,547,261	2,508,240	2,323,862
Income tax expense (benefit)	618,112	590,160	915,556
Net income	1,929,149	1,918,080	1,408,306
Average total assets	119,584,000	116,959,000	120,860,000
Capital expenditures	178,000	98,000	79,000
All Other [Member]
Segment Reporting Information [Line Items]
Net interest income	537,940	557,542	410,928
Noninterest income	695,443	651,439	609,945
Total income	1,233,383	1,208,981	1,020,873
Provision for credit losses	6,257	(8,128)	8,265
Amortization of core deposit and other intangible assets	18,430	23,462	30,306
Depreciation and other amortization	68,840	68,004	69,923
Other noninterest expense	1,157,432	1,125,428	1,019,465
Income before taxes	(17,576)	215	(107,086)
Income tax expense (benefit)	(28,625)	(54,766)	(40,752)
Net income	11,049	54,981	(66,334)
Average total assets	14,953,000	13,877,000	13,684,000
Capital expenditures	98,000	65,000	44,000
Business Banking [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Net interest income	451,307	434,579	393,948
Noninterest income	113,855	111,600	112,512
Total income	565,162	546,179	506,460
Provision for credit losses	16,501	10,916	15,598
Depreciation and other amortization	412	382	393
Other noninterest expense	319,136	305,340	294,493
Income before taxes	229,113	229,541	195,976
Income tax expense (benefit)	60,617	61,279	80,043
Net income	168,496	168,262	115,933
Average total assets	5,793,000	5,631,000	5,602,000
Capital expenditures	1,000
Commercial Banking [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Net interest income	828,888	821,812	809,301
Noninterest income	289,558	288,908	283,447
Total income	1,118,446	1,110,720	1,092,748
Provision for credit losses	25,580	8,976	11,876
Depreciation and other amortization	554	496	509
Other noninterest expense	384,013	364,102	339,936
Income before taxes	708,299	737,146	740,427
Income tax expense (benefit)	187,835	198,229	303,556
Net income	520,464	538,917	436,871
Average total assets	28,142,000	26,626,000	26,573,000
Capital expenditures	2,000
Commercial Real Estate [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Net interest income	692,526	665,220	649,378
Noninterest income	214,970	183,955	169,966
Total income	907,496	849,175	819,344
Provision for credit losses	1,537	3,159	(7,524)
Amortization of core deposit and other intangible assets	1,060	1,060	1,060
Depreciation and other amortization	25,560	25,852	24,410
Other noninterest expense	240,736	217,387	207,493
Income before taxes	638,603	601,717	593,905
Income tax expense (benefit)	152,977	148,807	229,770
Net income	485,626	452,910	364,135
Average total assets	23,921,000	22,885,000	22,741,000
Capital expenditures			1,000
Discretionary Portfolio [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Net interest income	209,807	228,051	277,095
Noninterest income	26,919	(9,690)	23,851
Total income	236,726	218,361	300,946
Provision for credit losses	3,608	6,683	31,119
Depreciation and other amortization	263	187	279
Other noninterest expense	52,901	65,393	76,021
Income before taxes	179,954	146,098	193,527
Income tax expense (benefit)	36,342	29,872	58,559
Net income	143,612	116,226	134,968
Average total assets	29,081,000	32,123,000	37,203,000
Capital expenditures		1,000
Residential Mortgage Banking [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Net interest income	20,008	13,933	30,328
Noninterest income	393,372	305,560	321,589
Total income	413,380	319,493	351,917
Provision for credit losses	382	(2,178)	1,254
Depreciation and other amortization	46,901	24,288	32,011
Other noninterest expense	274,414	241,624	247,639
Income before taxes	91,683	55,759	71,013
Income tax expense (benefit)	19,355	10,272	25,446
Net income	72,328	45,487	45,567
Average total assets	2,611,000	2,161,000	2,355,000
Capital expenditures	1,000	1,000
Retail Banking [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Net interest income	1,389,788	1,351,165	1,210,066
Noninterest income	327,562	324,228	329,833
Total income	1,717,350	1,675,393	1,539,899
Provision for credit losses	122,135	112,572	107,412
Depreciation and other amortization	38,394	35,274	38,234
Other noninterest expense	839,636	789,783	758,153
Income before taxes	717,185	737,764	636,100
Income tax expense (benefit)	189,611	196,467	258,934
Net income	527,574	541,297	377,166
Average total assets	15,083,000	13,656,000	12,702,000
Capital expenditures	$ 76,000	$ 31,000	$ 34,000

Segment Information - Intersegment Activity Eliminated in Arriving at Consolidated Totals was Included in "All Other" Category (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Revenues	$ 6,191,943	$ 5,928,302	$ 5,632,187
Income taxes (benefit)	618,112	590,160	915,556
Net income (loss)	1,929,149	1,918,080	1,408,306
Intersegment Activity Eliminated in Consolidated Totals [Member]
Segment Reporting Information [Line Items]
Revenues	(48,559)	(41,285)	(43,941)
Expenses	(18,218)	(24,660)	(32,623)
Income taxes (benefit)	(7,976)	(4,371)	(4,606)
Net income (loss)	$ (22,365)	$ (12,254)	$ (6,712)

- Definition

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

+ References + Details

Regulatory Matters - Summary of Required Minimum and Well Capitalized Capital Ratios (Detail)	Dec. 31, 2019
Banking And Thrift [Abstract]
Common equity Tier 1 ("CET1") to risk-weighted assets, Minimum	4.50%
Tier 1 capital to risk-weighted assets, Minimum	6.00%
Total capital to risk-weighted assets, Minimum	8.00%
Leverage — Tier 1 capital to average total assets, as defined	4.00%
Common equity Tier 1 ("CET1") to risk-weighted assets, Well Capitalized	6.50%
Tier 1 capital to risk-weighted assets, Well capitalized	8.00%
Total capital to risk-weighted assets, Well capitalized	10.00%
Leverage — Tier 1 capital to average total assets, as defined	5.00%

Regulatory Matters - Capital Ratios and Amounts of Company and its Banking Subsidiaries (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Ratio	4.50%
Ratio	6.00%
Ratio	8.00%
M&T Bank Corporation [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Amount	$ 10,053,887	$ 9,960,811
Ratio	9.73%	10.13%
Amount	$ 11,303,836	$ 11,193,770
Ratio	10.94%	11.38%
Amount	$ 13,480,612	$ 13,454,137
Ratio	13.05%	13.68%
Amount	$ 11,303,836	$ 11,193,770
Ratio	9.59%	9.88%
M&T Bank [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Amount	$ 10,649,953	$ 10,636,136
Ratio	10.34%	10.84%
Amount	$ 10,649,953	$ 10,636,136
Ratio	10.34%	10.84%
Amount	$ 12,342,834	$ 12,475,296
Ratio	11.99%	12.72%
Amount	$ 10,649,953	$ 10,636,136
Ratio	9.08%	9.42%
Wilmington Trust, N.A. [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Amount	$ 606,538	$ 585,767
Ratio	56.35%	60.69%
Amount	$ 606,538	$ 585,767
Ratio	56.35%	60.69%
Amount	$ 608,130	$ 589,671
Ratio	56.50%	61.10%
Amount	$ 606,538	$ 585,767
Ratio	13.12%	12.51%

Relationship with Bayview Lending Group LLC and Bayview Financial Holdings, L.P. - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Schedule of Equity Method Investments [Line Items]
Loan facility carrying amount	$ 6,986,186,000	$ 8,444,914,000
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	37,000,000	24,000,000	$ 0
Bayview Lending Group and Bayview Financial [Member]
Schedule of Equity Method Investments [Line Items]
Outstanding principal balances of mortgage servicing rights	2,200,000,000	2,500,000,000
Revenue from contract with customer	12,000,000	14,000,000	17,000,000
Bayview Financial [Member]
Schedule of Equity Method Investments [Line Items]
Outstanding principal balances of residential mortgage loans from Bayview Financial	62,800,000,000	56,800,000,000
Revenues from sub-servicing	125,000,000	114,000,000	$ 103,000,000
Investment securities in held-to-maturity portfolio securitized by Bayview Financial	93,000,000	$ 113,000,000
Bayview Financial [Member] \| Syndicated Loan Facility [Member]
Schedule of Equity Method Investments [Line Items]
Loan facility carrying amount	702,000,000
Bayview Financial [Member] \| Syndicated Loan Facility [Member] \| M&T Bank [Member]
Schedule of Equity Method Investments [Line Items]
Loan facility carrying amount	$ 88,000,000

Parent Company Financial Statements - Condensed Balance Sheet (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Investments in consolidated subsidiaries
Total assets	$ 119,872,757	$ 120,097,403
Liabilities
Long-term borrowings	6,986,186	8,444,914
Total liabilities	104,156,108	104,637,212
Shareholders’ equity	15,716,649	15,460,191	$ 16,250,819	$ 16,486,622
Total liabilities and shareholders’ equity	119,872,757	120,097,403
Parent Company [Member]
Assets
Cash in subsidiary bank	83,531	40,609
Due from consolidated bank subsidiaries
Money-market savings	876,819	856,881
Current income tax receivable	1,261	1,117
Total due from consolidated bank subsidiaries	878,080	857,998
Investments in consolidated subsidiaries
Banks	15,732,008	15,491,277
Other	301,765	324,360
Investments in trust preferred entities (note 19)	23,022	23,241
Other assets	67,732	64,187
Total assets	17,086,138	16,801,672
Liabilities
Accrued expenses and other liabilities	74,235	63,719
Long-term borrowings	1,295,254	1,277,762
Total liabilities	1,369,489	1,341,481
Shareholders’ equity	15,716,649	15,460,191
Total liabilities and shareholders’ equity	$ 17,086,138	$ 16,801,672

Parent Company Financial Statements - Condensed Statement of Income (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Expense
Interest on long-term borrowings	$ 239,242	$ 248,556	$ 189,372
Other expense	3,468,682	3,288,062	3,140,325
Income tax credits	(618,112)	(590,160)	(915,556)
Equity in undistributed income of subsidiaries
Net income	$ 1,929,149	$ 1,918,080	$ 1,408,306
Net income per common share
Basic	$ 13.76	$ 12.75	$ 8.72
Diluted	$ 13.75	$ 12.74	$ 8.70
Parent Company [Member]
Income
Dividends from consolidated bank subsidiaries	$ 2,025,000	$ 1,250,000	$ 1,540,000
Equity in earnings of Bayview Lending Group LLC	36,740	23,500	352
Other income	7,216	2,417	9,493
Total income	2,068,956	1,275,917	1,549,845
Expense
Interest on long-term borrowings	51,938	36,354	21,591
Other expense	25,236	23,894	19,636
Total expense	77,174	60,248	41,227
Income before income taxes and equity in undistributed income of subsidiaries	1,991,782	1,215,669	1,508,618
Income tax credits	8,313	8,446	26,453
Income before equity in undistributed income of subsidiaries	2,000,095	1,224,115	1,535,071
Equity in undistributed income of subsidiaries
Net income of subsidiaries	1,954,054	1,943,965	1,413,235
Less: dividends received	(2,025,000)	(1,250,000)	(1,540,000)
Equity in undistributed income of subsidiaries	(70,946)	693,965	(126,765)
Net income	$ 1,929,149	$ 1,918,080	$ 1,408,306
Net income per common share
Basic	$ 13.76	$ 12.75	$ 8.72
Diluted	$ 13.75	$ 12.74	$ 8.70

Parent Company Financial Statements - Condensed Statement of Cash Flows (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities
Net income	$ 1,929,149	$ 1,918,080	$ 1,408,306
Adjustments to reconcile net income to net cash provided by operating activities
Provision for deferred income taxes	57,548	15,857	400,790
Gain on sale of assets	31,526	(23,503)	(53,467)
Net cash provided by operating activities	2,357,555	2,089,852	2,781,935
Cash flows from investing activities
Other, net	(195,921)	47,904	19,825
Cash flows from financing activities
Purchases of treasury stock	(1,349,785)	(2,194,396)	(1,205,905)
Dividends paid — common	(552,138)	(510,382)	(457,402)
Dividends paid — preferred	(67,454)	(72,521)	(72,734)
Proceeds from long-term borrowings		1,773,189	2,145,950
Redemption of Series A and Series C preferred stock	(381,500)
Other, net	(25,393)	17,167	10,675
Supplemental disclosure of cash flow information
Interest received during the year	4,892,301	4,568,991	4,155,723
Income taxes received during the year	320,513	375,116	494,205
Series G Preferred Stock [Member]
Cash flows from financing activities
Proceeds from issuance of Series G preferred stock	396,000
Parent Company [Member]
Cash flows from operating activities
Net income	1,929,149	1,918,080	1,408,306
Adjustments to reconcile net income to net cash provided by operating activities
Equity in undistributed income of subsidiaries	70,946	(693,965)	126,765
Provision for deferred income taxes	5,263	4,949	4,543
Net change in accrued income and expense	(34,525)	(8,242)	(170)
Gain on sale of assets			(2,995)
Net cash provided by operating activities	1,970,833	1,220,822	1,536,449
Cash flows from investing activities
Proceeds from sales or maturities of investment securities	100
Other, net	51,235	29,933	12,407
Net cash provided by investing activities	51,335	29,933	12,407
Cash flows from financing activities
Purchases of treasury stock	(1,349,785)	(2,194,396)	(1,205,905)
Dividends paid — common	(552,138)	(510,382)	(457,402)
Dividends paid — preferred	(67,454)	(72,521)	(72,734)
Proceeds from long-term borrowings		748,595
Redemption of Series A and Series C preferred stock	(381,500)
Other, net	(4,431)	45,913	34,524
Net cash used by financing activities	(1,959,308)	(1,982,791)	(1,701,517)
Net increase (decrease) in cash and cash equivalents	62,860	(732,036)	(152,661)
Cash and cash equivalents at beginning of year	897,490	1,629,526	1,782,187
Cash and cash equivalents at end of year	960,350	897,490	1,629,526
Supplemental disclosure of cash flow information
Interest received during the year	1,752	2,219	2,313
Interest paid during the year	49,451	17,482	18,498
Income taxes received during the year	6,251	$ 6,362	$ 21,740
Parent Company [Member] \| Series G Preferred Stock [Member]
Cash flows from financing activities
Proceeds from issuance of Series G preferred stock	$ 396,000

Recent Accounting Developments - Additional Information (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Recognized right of use asset	$ 436,927
Recognizing lease liabilities	487,555
Allowance for credit losses	$ 1,051,071	$ 1,019,444	$ 1,017,198	$ 988,997
ASU 2016-02 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Lessee, operating lease term	12 months
Recognized right of use asset	$ 394,000
Recognizing lease liabilities	399,000
ASU 2016-13 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses	$ 132,000

Consolidated Statement of Changes in Shareholders' Equity (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Treasury Stock [Member] \| Series A Warrants [Member]
Exercise of warrants into shares of common stock		257,630	374,786
Exercise of warrants into shares of common stock		136,676	204,133
Retained Earnings [Member]
Common stock per share dividend amount	$ 4.10	$ 3.55	$ 3.00

Investment Securities - Amortized Cost and Estimated Fair Value of Collateralized Mortgage Obligations (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Amortized Cost And Fair Value Debt Securities [Abstract]
Collateralized mortgage obligations, Amortized cost	$ 94,817	$ 115,171
Collateralized mortgage obligations, Estimated fair value	$ 88,410	$ 105,155

Investment Securities - Investment Ratings of All Privately Issued Mortgage-Backed Securities and Other Debt Securities (Detail) $ in Thousands	Dec. 31, 2019 USD ($)
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Total securities with disclosed rating, Amortized Cost	$ 235,496
Total securities with disclosed rating, Estimated Fair Value	222,558
A or Better [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Total securities with disclosed rating, Estimated Fair Value	17,564
BBB [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Total securities with disclosed rating, Estimated Fair Value	83,660
BB [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Total securities with disclosed rating, Estimated Fair Value	19,106
B or Less [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Total securities with disclosed rating, Estimated Fair Value	20,671
Not Rated [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Total securities with disclosed rating, Estimated Fair Value	81,557
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	4,916
Total securities with disclosed rating, Estimated Fair Value	4,931
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	4,809
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	122
Privately Issued [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Total securities with disclosed rating, Amortized Cost	93,512
Total securities with disclosed rating, Estimated Fair Value	87,110
Privately Issued [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	8,015
Privately Issued [Member] \| BBB [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Total securities with disclosed rating, Estimated Fair Value	8,768
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	20,671
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	49,656
Other Debt Securities [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Total securities with disclosed rating, Amortized Cost	137,068
Total securities with disclosed rating, Estimated Fair Value	130,517
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	4,740
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	74,770
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	19,106
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	$ 31,901

Loans and Leases - Outstanding Principal Balance and Carrying Amount of Loans and Included in Consolidated Balance Sheet (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Outstanding principal and carrying value of acquired loans recorded at fair value
Outstanding principal balance	$ 769,414	$ 1,016,785
Carrying amount	535,596	727,491
Commercial, Financial, Leasing, etc. [Member]
Outstanding principal and carrying value of acquired loans recorded at fair value
Carrying amount	21,114	27,073
Commercial Real Estate [Member]
Outstanding principal and carrying value of acquired loans recorded at fair value
Carrying amount	94,890	135,047
Residential Real Estate [Member]
Outstanding principal and carrying value of acquired loans recorded at fair value
Carrying amount	341,807	473,511
Consumer [Member]
Outstanding principal and carrying value of acquired loans recorded at fair value
Carrying amount	$ 77,785	$ 91,860

Goodwill and Other Intangible Assets - Summary of Goodwill Assigned to Reportable Segments for Purposes of Testing for Impairment (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Goodwill [Line Items]
Goodwill	$ 4,593,112	$ 4,593,112
Business Banking [Member]
Goodwill [Line Items]
Goodwill	864,366
Commercial Banking [Member]
Goodwill [Line Items]
Goodwill	1,401,873
Commercial Real Estate [Member]
Goodwill [Line Items]
Goodwill	654,389
Retail Banking [Member]
Goodwill [Line Items]
Goodwill	1,309,191
All Other [Member]
Goodwill [Line Items]
Goodwill	$ 363,293

Revenue from Contracts with Customers - Additional Information (Detail1)	Dec. 31, 2018
Maximum [Member] \| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2018-01-01
Disaggregation Of Revenue [Line Items]
Period of satisfaction of contract with customer	1 year

Pension Plans and Other Postretirement Benefits - Fair Values of Company's Pension Plan Assets by Asset Category (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	$ 2,035,878	$ 1,831,773
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	1,488,940	1,373,040
Significant Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	314,701	300,101
Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	232,237	158,632
Money-Market Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	38,461	23,049
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	33,870	10,794
Money-Market Investments [Member] \| Significant Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	4,591	12,255
M&T Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	148,603	125,299
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	148,603	125,299
Domestic Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	219,663	191,640
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	219,663	191,640
International Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	10,476	7,752
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	10,476	7,752
Domestic Mutual Fund Equity securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	238,872	216,523
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	238,872	216,523
International Mutual Fund Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	381,433	316,923
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	381,433	316,923
Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	999,047	858,137
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	999,047	858,137
Corporate Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	112,783	103,672
Corporate Debt Securities [Member] \| Significant Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	112,783	103,672
Government Agency [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	190,679	182,034
Government Agency [Member] \| Significant Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	190,679	182,034
Non-U.S. Government [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	6,648	2,140
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	6,648	2,140
Domestic Mutual Fund Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	249,075	280,902
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	249,075	280,902
Total Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	559,185	589,409
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	249,075	301,563
Total Debt Securities [Member] \| Significant Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	310,110	287,846
Other Diversified Mutual Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	86,980	74,446
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	86,980	74,446
Other Real Estate Partnerships [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	21,905	11,807
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	3,939	2,791
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	17,966	9,016
Other Private Equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	87,966	63,699
Other Private Equity [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	87,966	63,699
Other Hedge Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	231,807	200,811
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	116,029	125,309
Other Hedge Funds [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	115,778	75,502
Guaranteed Deposit Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	10,527	10,415
Guaranteed Deposit Fund [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	10,527	10,415
Other Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	439,185	361,178
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	206,948	202,546
Other Securities [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	$ 232,237	158,632
International Mutual Fund Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets		20,661
International 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		$ 20,661

Comprehensive Income - Additional Information (Detail)	12 Months Ended
Comprehensive Income - Additional Information (Detail)	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement Of Income And Comprehensive Income [Abstract]
Federal income tax rate	21.00%	21.00%	35.00%

Comprehensive Income - Impact of Reclassification from AOCI to Retained Earnings (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($)
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Increase to retained earnings	$ 64,029
Net Unrealized Losses on Investment Securities [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Increase to retained earnings	8,065
Defined Benefit Plans Liability Adjustments [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Increase to retained earnings	53,960
Cash Flow Hedges and Other [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Increase to retained earnings	$ 2,004

Derivative Financial Instruments - Information about Fair Values of Derivative Instruments in Consolidated Balance Sheet (Parenthetical) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Offsetting [Abstract]
Reduction in estimated fair value of interest rate contracts in asset position	$ (43.3)	$ (170.7)
Reduction in estimated fair value of interest rate contracts in liability position	$ (281.3)	$ (49.7)

Fair Value Measurements - Assets and Liabilities Measured at Estimated Fair Value on Recurring Basis (Parenthetical) (Detail) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Transfer of asset from level 1 to 2	$ 0	$ 0
Transfer of asset from level 2 to 1	0	0
Transfer of liabilities from level 1 to 2	0	0
Transfer of liabilities from level 2 to 1	$ 0	$ 0

Commitments and Contingencies - Additional Information (Detail) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Loss Contingencies [Line Items]
Commitments to extend credit to commercial customers	$ 9,100,000,000	$ 8,600,000,000
Maximum credit risk for recourse associated with loans sold under Federal National Mortgage Association Delegated Underwriting and Servicing program	3,900,000,000	$ 3,400,000,000
Minimum [Member]
Loss Contingencies [Line Items]
Range of reasonably possible losses	0
Maximum [Member]
Loss Contingencies [Line Items]
Range of reasonably possible losses	$ 50,000,000

Segment Information - Additional Information (Detail)	12 Months Ended
Segment Information - Additional Information (Detail)	Dec. 31, 2019
Segment Reporting [Abstract]
Percent of maximum revenue from single customer on total revenues	10.00%

Regulatory Matters - Additional Information (Detail) - USD ($) $ in Millions	Dec. 31, 2019	Jan. 01, 2019	Dec. 31, 2018
Banking And Thrift [Abstract]
Funds available for payment of dividends to M&T from banking subsidiaries	$ 605
Required subsidiary noninterest-earning reserves against certain deposit liabilities	$ 666		$ 684
Capital conservation buffer		2.50%