Loans (a) Total Total Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Fee, and Loan in Process Commercial Commercial Real Estate Excluding Residential Builder And Developer And Other Construction [Member] Commercial real estate excluding residential builder and developer and other construction. Expected return on plan assets Defined Benefit Plan, Expected Return (Loss) on Plan Assets Award Timing Predetermined Award Timing Predetermined [Flag] Investments amortized to income tax expense Investment Program, Proportional Amortization Method, Applied, Amortization Expense Entity File Number Entity File Number Additional Paid-in Capital Additional Paid-in Capital [Member] Tabular List, Table Tabular List [Table Text Block] Other residential real estate Commitments To Extend Credit For Other Residential Real Estate Commitments to extend credit for other residential real estate. Carrying Amounts and Estimated Fair Value for Financial Instrument Assets (Liabilities) Fair Value, by Balance Sheet Grouping [Table Text Block] Debt Securities Debt Securities [Member] M&T Bank M&T Bank [Member] M&T Bank Noninterest-bearing deposits Noninterest-Bearing Deposit Liabilities, Domestic Measurement Basis [Axis] Measurement Basis [Axis] Adjustment to Compensation: Adjustment to Compensation [Axis] HTM, 12 months or longer, fair value Debt Securities, Held-to-Maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value Named Executive Officers, Footnote Named Executive Officers, Footnote [Text Block] Maturity Period 2026 Maturity Period Two [Member] Maturity Period Two [Member]. Revenue from contracts with customers Revenue from Contract with Customer [Text Block] Financing Receivable Portfolio Segment Financing Receivable Portfolio Segment [Domain] Dividends paid — preferred Payments of Ordinary Dividends, Preferred Stock and Preference Stock Recoveries Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Recovery Schedule of Stock by Class [Table] Stock, Class of Stock [Table] Adjustment to Compensation, Amount Adjustment to Compensation Amount Pension Benefits Pension Plan [Member] Employee Stock Option Share-Based Payment Arrangement, Option [Member] Pledged financial instruments Financing Receivable, after Allowance for Credit Loss Asset Pledged as Collateral without Right Asset Pledged as Collateral without Right [Member] Residential builder and developer Residential Builder And Developer [Member] Residential builder and developer. Common stock cash dividends Dividends, Common Stock, Cash Asset write-downs Asset Impairment Charges Total shareholders’ equity Beginning balance Ending balance Equity, Attributable to Parent Measurement Frequency Measurement Frequency [Axis] Debt Securities, Available-for-Sale [Table] Debt Securities, Available-for-Sale [Table] Other comprehensive income (loss), net of tax and reclassification adjustments: Other Comprehensive Income (Loss), Net of Tax [Abstract] Insider Trading Policies and Procedures [Line Items] Common stock authorized (in shares) Common Stock, Shares Authorized Cash and cash equivalents Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract] Recurring Fair Value, Recurring [Member] Five Point Four Zero Percentage Fixed Rate Senior Notes Due To Mature In July 2030 Five Point Four Zero Percentage Fixed Rate Senior Notes Due To Mature In July 2030 [Member] Five Point Four Zero Percentage Fixed Rate Senior Notes Due To Mature In July 2030 Total debt securities gross unrealized losses Investment In Debt Securities Gross Unrealized Losses Investment in debt securities gross unrealized losses. Criticized accrual Criticized Accrual [Member] Criticized accrual. Cover [Abstract] Cover [Abstract] Fair Value Measurements Portion at Fair Value Measurement [Member] Maximum Maximum [Member] Real estate acquired in settlement of loans Real Estate Owned, Transfer to Real Estate Owned Mortgage-backed securities Debt Securities, Held-to-Maturity, Amortized Cost, after Allowance for Credit Loss, Maturity, without Single Maturity Date Core deposit and other intangible assets Finite-Lived Intangible Assets, Net Due after ten years Debt Securities, Available-for-Sale, Amortized Cost, Maturity, Allocated and Single Maturity Date, after Year 10 Remaining collateral balance Debt Instrument, Collateral Amount Non-PEO NEO Average Total Compensation Amount Non-PEO NEO Average Total Compensation Amount Debt Instrument [Line Items] Debt Instrument [Line Items] Adjustment to Non-PEO NEO Compensation Footnote Adjustment to Non-PEO NEO Compensation Footnote [Text Block] Schedule Of Financing Receivable Recorded Investment Credit Quality Indicator [Table] Financing Receivable, Credit Quality Indicator [Table] Indirect expense Indirect Expense (Income) Indirect Expense (Income) Retirement Benefits [Abstract] Retirement Benefits [Abstract] Forgone Recovery due to Disqualification of Tax Benefits, Amount Forgone Recovery due to Disqualification of Tax Benefits, Amount Non-Rule 10b5-1 Arrangement Terminated Non-Rule 10b5-1 Arrangement Terminated [Flag] Income before taxes Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Entity Shell Company Entity Shell Company Revolving Loans Converted to Term Loans Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan Schedule of Long-Term Debt Instruments [Table] Schedule of Long-Term Debt Instruments [Table] Mortgage-backed securities Debt Securities, Held-to-Maturity, Maturity, without Single Maturity Date, Fair Value Statement of Stockholders' Equity [Abstract] Statement of Stockholders' Equity [Abstract] Amortization of capitalized servicing rights Amortization of Mortgage Servicing Rights (MSRs) Operating Segments Operating Segments [Member] FHLB of New York FHLB of New York [Member] FHLB of New York. Award Timing MNPI Considered Award Timing MNPI Considered [Flag] Total interest expense Interest Expense, Operating Loans And Leases Receivable [Line Items] Loans And Leases Receivable [Line Items] Loans and leases receivable. Due in one year or less Debt Securities, Held-to-Maturity, Amortized Cost, after Allowance for Credit Loss, Maturity, Allocated and Single Maturity Date, Year One Document Fiscal Period Focus Document Fiscal Period Focus Derivatives, Fair Value [Line Items] Derivatives, Fair Value [Line Items] Award Timing Method Award Timing Method [Text Block] Amortized Cost Total Financing Receivable, Excluding Accrued Interest, Nonaccrual Award Type Award Type [Axis] Hedging Relationship Hedging Relationship [Domain] Other Other Loans [Member] Other loans. Investment, Name Investment, Name [Domain] Trading Symbol Trading Symbol Long-term borrowings Interest Expense, Long-Term Debt Entity Address, City or Town Entity Address, City or Town Other securities, estimated fair value Federal Home Loan Bank Stock and Federal Reserve Bank Stock Class of Financing Receivable [Axis] Class of Financing Receivable [Axis] Variable interest entities and asset securitizations Variable Interest Entities And Asset Securitizations [Text Block] Variable interest entities and asset securitizations. Non-PEO NEO Average Compensation Actually Paid Amount Non-PEO NEO Average Compensation Actually Paid Amount Income Statement Location Statement of Income Location, Balance [Domain] Merchant discount and credit card interchange fees Credit Card, Merchant Discount [Member] Compensation Actually Paid vs. Other Measure Compensation Actually Paid vs. Other Measure [Text Block] Equipment finance loans and leases Equipment Finance Loans And Leases [Member] Equipment Finance Loans And Leases Short-term borrowings Interest Expense, Short-Term Borrowings Total debt securities amortized cost Investment In Debt Securities Amortized Cost Investment in debt securities amortized cost. Entity Emerging Growth Company Entity Emerging Growth Company HTM, Less than 12 months, gross unrealized losses Debt Securities, Held-to-Maturity, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year [Member] Unfunded Loan Commitment Unfunded Loan Commitment [Member] Derivatives in fair value hedging relationships, derivative Derivative, Gain (Loss) on Derivative, Net Time deposits Interest Expense, Time Deposits Total other income Noninterest income Noninterest Income Gross unrealized losses for held to maturity Debt Securities, Held-to-Maturity, Accumulated Unrecognized Loss Other assets Other Assets, Fair Value Disclosure Brokerage services income Brokerage Services Income [Member] Brokerage Services Income Loans and allowance for loan losses Loans, Notes, Trade and Other Receivables Disclosure [Text Block] Other expense Noninterest Expense [Abstract] Summary of Sources of Noninterest Income that are Subject to Revenue Recognition Accounting Guidance Disaggregation of Revenue [Table Text Block] Cash and due from banks Cash and Due from Banks Federal tax credits and other federal tax benefits recognized Investment Program, Proportional Amortization Method, Elected, Income Tax Credit and Other Income Tax Benefit, before Amortization Expense Class of Financing Receivable [Domain] Class of Financing Receivable [Domain] Savings and interest-checking deposits Savings And Interest Checking Deposits Amount of domestic interest-bearing checking and savings accounts, which may include money market accounts, NOW accounts, interest-bearing corporate checking accounts, brokered deposits and other savings accounts. Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year [Member] Derivative Instruments and Hedging Activities Disclosure [Abstract] Derivative Instruments and Hedging Activities Disclosure [Abstract] Due after one year through five years Debt Securities, Held-to-Maturity, Fair Value, Maturity, Allocated and Single Maturity Date, after Year One Through Five Pledged Status [Domain] Pledged Status [Domain] Entity Address, Postal Zip Code Entity Address, Postal Zip Code Restatement Determination Date Restatement Determination Date Income taxes Income tax expense (benefit) Income Tax Expense (Benefit) Payments to Acquire Loans Receivable Payments to Acquire Loans Receivable Variable rate Debt Instrument, Basis Spread on Variable Rate Document Information [Line Items] Document Information [Line Items] Preferred stock, shares issued (in shares) Preferred Stock, Shares Issued Pension Adjustments Service Cost Pension Adjustments Service Cost [Member] Designated as Hedging Instrument Designated as Hedging Instrument [Member] Fair Value Hierarchy and NAV Fair Value Hierarchy and NAV [Axis] Hedging Relationship Hedging Relationship [Axis] Cash flow hedges adjustments Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification and Tax Due in one year or less Debt Securities, Held-to-Maturity, Fair Value, Maturity, Allocated and Single Maturity Date, Year One Compensation Actually Paid vs. Company Selected Measure Compensation Actually Paid vs. Company Selected Measure [Text Block] Commitments to sell real estate loans Commitments To Sell Real Estate Loans [Member] Commitments to sell real estate loans. Revenues from sub-servicing Revenues From Subservicing Revenues from sub-servicing All Trading Arrangements All Trading Arrangements [Member] Equity Awards Adjustments, Footnote Equity Awards Adjustments, Footnote [Text Block] Total Shareholder Return Vs Peer Group Total Shareholder Return Vs Peer Group [Text Block] Interest Payments On Variable Rate Commercial Real Estate Loans Interest Payments On Variable Rate Commercial Real Estate Loans [Member] Interest payments on variable rate commercial real estate loans. Less: Preferred stock dividends Preferred Stock Dividends, Income Statement Impact Total investment securities, 12 months or longer, fair value Investment Securities Continuous Unrealized Loss Position Twelve Months Or Longer Fair Value This item represents the fair value of securities that have been in a continuous loss position for twelve months or longer. Other revenues from operations Noninterest Income, Other Operating Income Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Abstract] Net cash from operating activities Cash Provided by (Used in) Operating Activity, Including Discontinued Operation Weighted-Average Life Debt Instrument, Term Investment securities available for sale: Debt Securities, Available-for-Sale, Excluding Accrued Interest Equity Method Investments and Joint Ventures [Abstract] Equity Method Investments and Joint Ventures [Abstract] Investment securities available for sale Proceeds from Sale of Debt Securities, Available-for-Sale Preferred stock, par value (in dollars per share) Preferred Stock, Par or Stated Value Per Share Subsequent Event Subsequent Event [Member] Schedule of Equity Method Investments [Line Items] Schedule of Equity Method Investments [Line Items] Net interest income Net Interest Income Interest Income (Expense), Operating Equity Valuation Assumption Difference, Footnote Equity Valuation Assumption Difference, Footnote [Text Block] PEO Total Compensation Amount PEO Total Compensation Amount Liability derivatives, fair value Derivative Liability, Subject to Master Netting Arrangement, before Offset Weighted-average shares outstanding: Weighted Average Number of Shares Outstanding, Basic [Abstract] Equity Components Equity Components [Axis] Year four Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year Commitments to originate real estate loans for sale Mortgage Related Commitments To Originate Real Estate Loans For Sale [Member] Mortgage related commitments to originate real estate loans for sale. Revolving Loans Converted to Term Loans Revolving Loans Converted To Term Loans [Member] Revolving loans converted to term loans. Non-Rule 10b5-1 Arrangement Adopted Non-Rule 10b5-1 Arrangement Adopted [Flag] Entity Address, State or Province Entity Address, State or Province Total interest income Interest and Dividend Income, Operating Financial Asset, Aging [Domain] Financial Asset, Aging [Domain] Loans measured at fair value on nonrecurring basis Loans Receivable, Fair Value Disclosure Individual: Individual [Axis] Reduction in estimated fair value of interest rate contracts in asset position Increase Decrease In Estimated Fair Value Of Interest Rate Contracts In Asset Position Increase (decrease) in estimated fair value of interest rate contracts in asset position. Dividends paid — common Payments of Ordinary Dividends, Common Stock Net change in loans originated for sale Increase (Decrease) in Loan, Held-for-Sale Mortgage-backed securities Debt Securities, Available-for-Sale, Maturity, without Single Maturity Date, Amortized Cost Maximum exposure to loss of investments in real estate partnerships Maximum Exposure To Loss Of Investments In Real Estate Partnerships Maximum exposure to loss of investments in real estate partnerships. Forgone Recovery, Explanation of Impracticability Forgone Recovery, Explanation of Impracticability [Text Block] Payments on long-term borrowings Repayments of Long-Term Debt Entity Interactive Data Current Entity Interactive Data Current Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff, by Origination Year [Abstract] Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff, by Origination Year [Abstract] Commercial Bank Commercial Banking [Member] Commercial banking segment. Interest income Interest and Dividend Income, Operating [Abstract] Total other expense Noninterest Expense Residential real estate loans to be sold Commitments To Extend Credit For Residential Real Estate Loans To Be Sold Commitments to extend credit for residential real estate loans to be sold. Disaggregation Of Revenue [Table] Disaggregation of Revenue [Table] Term Extension Payment Deferral [Member] Other income Noninterest Income [Abstract] Recreational finance Recreational Finance [Member] Recreational finance. Entity Central Index Key Entity Central Index Key Investment in partnership carrying amount Investments In Variable Interest Entity Carrying Amount The carrying amount of investments in variable interest entity. PEO Name PEO Name Total revenue Revenues Prior Year End Fair Value of Equity Awards Granted in Any Prior Year that Fail to Meet Applicable Vesting Conditions During Covered Year Prior Year End Fair Value of Equity Awards Granted in Any Prior Year that Fail to Meet Applicable Vesting Conditions During Covered Year [Member] Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Outstanding Aggregate Erroneous Compensation Amount Outstanding Aggregate Erroneous Compensation Amount Equity and other securities (cost: $1,003 at June 30, 2025; $1,007 at December 31, 2024) Equity and other securities, estimated fair value Equity And Other Securities Estimated Fair Value Equity and other securities estimated fair value. Computations of Basic Earnings Per Common Share Schedule of Earnings Per Share, Basic, by Common Class, Including Two Class Method [Table Text Block] Schedule Of Defined Benefit Plans Disclosures [Table] Defined Benefit Plan [Table] Schedule Of Segment Reporting Information By Segment [Table] Schedule of Segment Reporting Information, by Segment [Table] Information about Fair Values of Derivative Instruments in Consolidated Balance Sheet Schedule of Derivative Instruments in Statement of Financial Position, Fair Value [Table Text Block] Exercise Price Award Exercise Price Entity Filer Category Entity Filer Category Class of Stock Class of Stock [Domain] Subsequent Event Type [Axis] Subsequent Event Type [Axis] Balance Sheet Location Statement of Financial Position Location, Balance [Axis] Reduction in estimated fair value of interest rate contracts in liability position Increase Decrease In Estimated Fair Value Of Interest Rate Contracts In Liability Position Increase (decrease) in estimated fair value of interest rate contracts in liability position. Financing receivable, before allowance for credit loss Financing Receivable, before Allowance for Credit Loss Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year [Member] Entity Address, Address Line One Entity Address, Address Line One Commitments to extend credit Commitments To Extend Credit [Abstract] Commitments to extend credit. Accumulated Other Comprehensive Income (Loss), Net AOCI Attributable to Parent AOCI Attributable to Parent [Member] Investments Investments [Domain] Revolving Loans Converted to Term Loans Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan, Writeoff Internal Credit Assessment Internal Credit Assessment [Axis] Internal Credit Assessment Internal Credit Assessment [Domain] Other Revenue Portfolio Segment Other Revenue Portfolio Segment [Member] Other Revenue Portfolio Segment Readily marketable securities gross unrealized gains Readily Marketable Securities At Fair Value Gross Unrealized Gains Readily marketable securities at fair value gross unrealized gains. Derivative financial instruments Derivative Instruments and Hedging Activities Disclosure [Text Block] Amortization of prior service credit Defined Benefit Plan, Amortization of Prior Service Cost (Credit) Other Revenues From Operations Other Revenues From Operations [Member] Other revenues from operations. Schedule of Preferred Stock Schedule of Stock by Class [Table Text Block] Fair Value as of Grant Date Award Grant Date Fair Value Cost method equity securities Equity Securities, FV-NI, Cost Financing Receivable, Impaired [Line Items] Financing Receivable, Impaired [Line Items] Year five Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year Fair Value Measurements Fair Value, Inputs, Level 1, Level 2, and Level 3 [Member] Salaries and employee benefits Labor and Related Expense Privately issued Mortgage-Backed Securities, Issued by Private Enterprises [Member] Plus: Incremental shares from assumed conversion of stock-based compensation awards (in shares) Incremental Common Shares Attributable to Dilutive Effect of Share-Based Payment Arrangements Document Quarterly Report Document Quarterly Report AFS, less than 12 months, fair value Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months Deferred income taxes and credits Deferred Income Taxes and Tax Credits Changed Peer Group, Footnote Changed Peer Group, Footnote [Text Block] HTM, 12 months or longer, gross unrealized losses Debt Securities, Held-to-Maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss Counterparty Name [Domain] Counterparty Name [Domain] Fair Values Derivatives Balance Sheet Location By Derivative Contract Type By Hedging Designation [Table] Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] Maturity Period 2025 Maturity Period One [Member] Maturity Period One [Member]. Adjustment To PEO Compensation, Footnote Adjustment To PEO Compensation, Footnote [Text Block] Investment Securities in Continuous Unrealized Loss Position Investment Securities In Continuous Unrealized Loss Position [Table Text Block] Investment securities in continuous unrealized loss position. Loans Insured or Guaranteed by Government Authorities [Domain] Loans Insured or Guaranteed by Government Authorities [Domain] Investment Type Investment Type [Axis] Total investment securities Investment securities held to maturity Investments Title Trading Arrangement, Individual Title Peer Group Total Shareholder Return Amount Peer Group Total Shareholder Return Amount Collateral relating to net asset positions Derivative Asset, Fair Value of Collateral Non-PEO NEO Non-PEO NEO [Member] Standby letters of credit Letters of Credit Outstanding, Amount Loans secured by residential real estate that were in the process of foreclosure Residential Mortgage Loans Secured By Residential Real Estate In Process Of Foreclosure Residential mortgage loans secured by residential real estate in process of foreclosure. Preferred stock dividend rate (as a percent) Preferred Stock, Dividend Rate, Percentage Trading account and other non-hedging derivative gains Trading Gain (Loss) Accumulated Other Comprehensive Income (Loss) [Line Items] Accumulated Other Comprehensive Income (Loss) [Line Items] Investment securities available for sale, gross unrealized gains Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax All Award Types Award Type [Domain] Prior Service Credit Accumulated Defined Benefit Plans Adjustment, Net Prior Service Attributable to Parent [Member] Retail Bank Retail Banking [Member] Retail banking segment. Equity Awards Adjustments Equity Awards Adjustments [Member] Equity, attributable to parent, beginning balance Equity, attributable to parent, ending balance Equity, attributable to parent, before tax Equity, Attributable to Parent, Before Tax Equity, Attributable to Parent, Before Tax Pension Benefits Adjustments, Footnote Pension Benefits Adjustments, Footnote [Text Block] Disaggregation Of Revenue [Line Items] Disaggregation of Revenue [Line Items] Defined Benefit Plan Disclosure [Line Items] Defined Benefit Plan Disclosure [Line Items] Compensation Amount Outstanding Recovery Compensation Amount Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Recovery of Erroneously Awarded Compensation Disclosure [Line Items] Estimated Fair Value Estimate of Fair Value Measurement [Member] Retirement Plan Type Retirement Plan Type [Domain] MNPI Disclosure Timed for Compensation Value MNPI Disclosure Timed for Compensation Value [Flag] Aggregate fair value of derivative financial instruments in asset position Derivative Asset, Subject to Master Netting Arrangement, before Offset of Collateral Due after one year through five years Debt Securities, Available-for-Sale, Amortized Cost, Maturity, Allocated and Single Maturity Date, after Year One Through Five Commercial real estate loans to be sold Commitments To Extend Credit For Commercial Real Estate Loans To Be Sold Commitments to extend credit for commercial real estate loans to be sold. 30-89 days past due Financial Asset, 30 to 89 Days Past Due [Member] Financial Asset, 30 to 89 Days Past Due Service charges on deposit accounts Deposit Account [Member] Financing Receivable, Past Due [Line Items] Financing Receivable, Past Due [Line Items] Due after five years through ten years Debt Securities, Available-for-Sale, Amortized Cost, Maturity, Allocated and Single Maturity Date, after Year 5 Through 10 Equity and other securities, cost Equity and other securities, cost Equity And Other Securities At Cost Equity and other securities at cost. Accumulated other comprehensive income (loss), net Accumulated Other Comprehensive Income (Loss), Net of Tax Financial Instruments Financial Instruments [Domain] Net unrealized gains on investment securities OCI, Debt Securities, Available-for-Sale, Gain (Loss), after Adjustment and Tax Due after ten years Debt Securities, Held-to-Maturity, Fair Value, Maturity, Allocated and Single Maturity Date, after Year 10 Aggregate Pension Adjustments Service Cost Aggregate Pension Adjustments Service Cost [Member] Pledging Purpose [Domain] Pledging Purpose [Domain] Minimum Minimum [Member] February 2025 Asset Backed Notes February 2025 [Member] Asset Backed Notes February 2025 Net interest income after provision for credit losses Interest Income (Expense), after Provision for Loan Loss Financing receivable, accrued interest, before allowance for credit loss Financing Receivable, Accrued Interest, before Allowance for Credit Loss Accounts, Notes, Loans and Financing Receivable [Line Items] Accounts, Notes, Loans and Financing Receivable [Line Items] Company Selected Measure Name Company Selected Measure Name Equity and other securities Payments To Acquire Equity And Other Securities Investments Payments to acquire equity and other securities investments. Fair Value Measurement Fair Value Measurement [Domain] Borrowings Debt Disclosure [Text Block] Aggregate Available Trading Arrangement, Securities Aggregate Available Amount Stock Appreciation Rights (SARs) Stock Appreciation Rights (SARs) [Member] Due after ten years Debt Securities, Held-to-Maturity, Amortized Cost, after Allowance for Credit Loss, Maturity, Allocated and Single Maturity Date, after Year 10 Diluted Net income available to common shareholders Net Income (Loss) Available to Common Stockholders, Diluted Collateral Held Collateral Held [Domain] Commitments and contingencies Commitments and Contingencies Disclosure [Text Block] Hedged item Derivative Assets (Liabilities), at Fair Value, Net Schedule Of Borrowings [Table] Schedule Of Borrowings [Table] Schedule of borrowings. Diluted (in shares) Adjusted weighted-average shares outstanding (in shares) Weighted Average Number of Shares Outstanding, Diluted Non-GAAP Measure Description Non-GAAP Measure Description [Text Block] Derivative [Table] Derivative [Table] Junior subordinated debentures — M&T (a) Junior Subordinated Notes Entity Small Business Entity Small Business Debt securities held to maturity: Debt Securities, Held-to-Maturity, Amortized Cost, after Allowance for Credit Loss, Maturity [Abstract] Loan and Leases Considered Nonaccrual and Interest Income Recognized on Loans Loan And Leases Considered Nonaccrual And Interest Income Recognized On Loans [Table Text Block] Loan and leases considered nonaccrual and interest income recognized on loans. Weighted-Average Maturity (In years) Derivative, Average Remaining Maturity Preferred stock, shares outstanding (in shares) Preferred Stock, Shares Outstanding Document Transition Report Document Transition Report Due after one year through five years Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, after Year One Through Five Net income available to common equity Net Income Loss Available To Common Stockholders Diluted Before Unvested Stock Based Compensation Awards Adjustment Net income loss available to common stockholders before unvested stock based compensation awards adjustment as used in the determination of diluted earnings per common share. Long-term Debt Long-Term Debt [Member] Stock-based compensation transactions, net Share Based Compensation Expense Net The adjustment to common stock or additional paid in capital for the amount of recognized equity-based compensation during the period. Underlying Securities Award Underlying Securities Amount Equity Component Equity Component [Domain] Document Period End Date Document Period End Date Outstanding principal balances of mortgage servicing rights Mortgage Loans Of Privately Held Company Mortgage servicing rights of commercial mortgage loans with outstanding principal balances of privately held commercial mortgage company. Awards Close in Time to MNPI Disclosures, Table Awards Close in Time to MNPI Disclosures [Table Text Block] Less: Income attributable to unvested stock-based compensation awards Income Attributable To Unvested Stock Based Compensation Awards Basic Income attributable to unvested stock based compensation awards. This amount is used as a reduction to net income available to common equity in the calculation of net income available to common shareholders as used in the determination of basic earnings per common share. Net change in loan servicing advances Net Increase Decrease In Loan Servicing Advances The net cash outflow or inflow for the increase (decrease) of loan servicing advances. Document Type Document Type Level 3 Fair Value, Inputs, Level 3 [Member] Earnings per common share Earnings Per Share [Text Block] Name Outstanding Recovery, Individual Name Loss Contingencies [Table] Loss Contingencies [Table] Advertising and marketing Marketing and Advertising Expense Additional paid-in capital Additional Paid in Capital Product and Service Product and Service [Axis] Advances from FHLB Long-Term Federal Home Loan Bank Advances Net Periodic Defined Benefit Cost for Defined Benefit Plans Schedule of Defined Benefit Plans Disclosures [Table Text Block] Revolving Loans Financing Receivable, Excluding Accrued Interest, Revolving, Writeoff Revenue from contract with customer Revenue from Contract with Customer, Excluding Assessed Tax Statistical Measurement Statistical Measurement [Axis] Loss contingency accrual Loss Contingency Accrual Year two Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year, Writeoff Aggregate Erroneous Compensation Amount Aggregate Erroneous Compensation Amount Number of debt securities with aggregate gross unrealized losses Number Of Debt Securities With Gross Losses Number of debt securities with gross losses. Peer Group Issuers, Footnote Peer Group Issuers, Footnote [Text Block] Basic Net income available to common shareholders Net Income (Loss) Available to Common Stockholders, Basic Other comprehensive income (loss), net of Tax, Portion attributable to parent Total other comprehensive income (loss) Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent Other liabilities Other Liabilities, Fair Value Disclosure Information about Fair Values of Derivative Instruments in Consolidated Statement of Income Derivative Instruments, Gain (Loss) [Table Text Block] Amortized cost Financing Receivable, Excluding Accrued Interest, Modified, after 12 Months Level 1 Fair Value, Inputs, Level 1 [Member] Diluted (in USD per share) Diluted earnings per common share (in USD per share) Earnings Per Share, Diluted FDIC assessments Federal Deposit Insurance Corporation Premium Expense Supplemental schedule of noncash investing and financing activities Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract] Due after five years through ten years Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, after Year 5 Through 10 AOCI Attributable to Parent, Net of Tax [Roll Forward] AOCI Attributable to Parent, Net of Tax [Roll Forward] Modified in period Financing Receivable, Excluding Accrued Interest, Modified in Period, Amount Preferred stock cash dividends Dividends, Preferred Stock, Cash Treasury stock (in shares) Treasury Stock, Common, Shares Consolidation Items Consolidation Items [Domain] Summary of Loan grades applied various classes of Commercial and Real Estate Loans Summary Of Loan Grades Applied Various Classes Of Commercial And Real Estate Loans [Table Text Block] Summary of loan grades applied various classes of commercial and real estate loans. Investments, Debt and Equity Securities [Abstract] Investments, Debt and Equity Securities [Abstract] Beginning balance Ending balance Equity, Attributable To Parent, Tax Equity, Attributable To Parent, Tax Financing Receivable Portfolio Segment Financing Receivable Portfolio Segment [Axis] Noncontrolling Interest [Abstract] Modified past due 90 days or more Delinquency Status of Loans and Leases Receivable Modified Past Due Ninety Days or More Delinquency status of loans and leases receivable modified past due ninety days or more. Other commercial construction Other Commercial Construction [Member] Other commercial construction. Income taxes paid during the period Income Taxes Paid, Net Common shares outstanding (including common stock issuable) and unvested stock-based compensation awards (in shares) Common shares outstanding (including common stock issuable) and unvested stock-based compensation awards (in shares) Common Shares Outstanding Including Common Stock Issuable And Unvested Stock Based Compensation Awards The weighted average number of common shares outstanding (including common stock issuable) and unvested stock-based compensation awards. Bayview Financial Bayview Financial [Member] Bayview Financial. Other Projects Other Projects [Member] Other Projects Derivatives in fair value hedging relationships, hedged item Gain Loss On Hedged Item In Fair Value Hedge Aggregate net gain and losses (whether realized or unrealized) of the hedged item in a fair value hedge recognized in the income statement. Loans Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss Available line of credit Line of Credit Facility, Current Borrowing Capacity Expiration Date Trading Arrangement Expiration Date Other Commitments [Domain] Other Commitments [Domain] March 2024 Asset Backed Notes March 2024 [Member] Asset Backed Notes March 2024 Variable Derivative, Average Variable Interest Rate Premises and equipment Property, Plant and Equipment, Net August 2024 Asset Backed Notes August 2024 [Member] Asset Backed Notes August 2024 Compensation Actually Paid vs. Net Income Compensation Actually Paid vs. Net Income [Text Block] Entity Current Reporting Status Entity Current Reporting Status Receivables [Abstract] Receivables [Abstract] Derivative [Line Items] Derivative [Line Items] Capital expenditures, net Payments for (Proceeds from) Productive Assets Awards Close in Time to MNPI Disclosures Awards Close in Time to MNPI Disclosures [Table] Collateral Held Collateral Held [Axis] Consolidated Entities Consolidated Entities [Domain] Due in one year or less Debt Securities, Available-for-Sale, Amortized Cost, Maturity, Allocated and Single Maturity Date, Year One Measurement Input, Commitment Expiration Measurement Input, Commitment Expiration [Member] Measurement Input, Commitment Expiration Financial Instrument Financial Instrument [Axis] Statement of Financial Position [Abstract] Statement of Financial Position [Abstract] Executive Category: Executive Category [Axis] AFS, 12 months or longer, gross unrealized losses Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss Credit cards Commitments To Extend Credit For Credit Cards Commitments To Extend Credit For Credit Cards Proceeds from long-term borrowings Proceeds from Issuance of Long-Term Debt Current Fiscal Year End Date Current Fiscal Year End Date AFS, less than 12 months, gross unrealized losses Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss Total deposits Deposits Deposits Professional and other services Professional Fees Held to maturity (fair value: $12,073 at June 30, 2025; $12,955 at December 31, 2024) Amortized cost for held to maturity Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss Amortized Cost and Estimated Fair Value of Debt Securities by Contractual Maturity Amortized Cost And Estimated Fair Value Of Debt Securities By Contractual Maturity [Table Text Block] Amortized cost and estimated fair value of debt securities by contractual maturity. 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Antidilutive securities excluded from computation of earnings per share Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Average common shares outstanding Adjusted weighted-average shares outstanding: Weighted Average Number of Shares Outstanding, Diluted [Abstract] Loans And Leases Receivable [Table] Loans And Leases Receivable [Table] Loans and Leases receivable. 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Other direct expenses Other Direct Expenses Other Direct Expenses Amortized Cost without Allowance Financing Receivable, Excluding Accrued Interest, Nonaccrual, No Allowance Pledged Status [Axis] Pledged Status [Axis] Investment securities available for sale, gross unrealized losses Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax Asset-backed notes (a) Secured Long-Term Debt, Noncurrent Trading Arrangements, by Individual Trading Arrangements, by Individual [Table] Basic (in USD per share) Basic earnings per common share (in USD per share) Earnings Per Share, Basic Less: Unvested stock-based compensation awards (in shares) Unvested Stock Based Compensation Awards Number of shares related to unvested stock-based compensation awards. This amount is a reduction in the calculation of weighted average shares outstanding for the earnings per share calculation. Preferred stock per share dividend amount (in USD per share) Preferred Stock, Dividends Per Share, Declared Unrealized losses on individual debt securities Debt Securities, Unrealized Gain (Loss) Information about Company's Segments Schedule of Segment Reporting Information, by Segment [Table Text Block] Short-term borrowings Total short-term borrowings Short-Term Debt Debt Instrument, Redemption, Period Debt Instrument, Redemption, Period [Axis] Forward-Starting Interest Rate Swap Agreements Forward Starting Interest Rate Swap Agreements [Member] Forward starting interest rate swap agreements. Uncollected amounts receivable Revenue, Remaining Performance Obligation, Amount Gross unrealized gains for held to maturity Debt Securities, Held-to-Maturity, Accumulated Unrecognized Gain Measurement Input Type [Domain] Measurement Input Type [Domain] Estimated fair value gain (loss) Increase (Decrease) in Fair Value of Interest Rate Fair Value Hedging Instruments Total Total Charge-offs Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff Award Timing MNPI Disclosure Award Timing MNPI Disclosure [Text Block] Variable Interest Entity Primary Beneficiary Variable Interest Entity, Primary Beneficiary [Member] Trading account Debt Securities, Trading, and Equity Securities, FV-NI Accounts and Financing Receivables [Table] Accounts and Financing Receivables [Table] Derivative Instruments, Gain (Loss) [Line Items] Derivative Instruments, Gain (Loss) [Line Items] OCI, before reclassifications, net of tax, attributable to parent OCI, before Reclassifications, Net of Tax, Attributable to Parent Hedging Designation Hedging Designation [Domain] Mortgage loans held for sale Financing Receivable, Held-for-Sale, Not Part of Disposal Group, after Valuation Allowance Total liabilities and shareholders’ equity Liabilities and Equity Defined Benefit Plans Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member] Derivative Instruments Gain Loss By Hedging Relationship By Income Statement Location By Derivative Instrument Risk [Table] Derivative Instruments, Gain (Loss) [Table] Commitments and Contingent Liabilities Outstanding Commitments [Table Text Block] The tabular disclosure of commitments. Commitments to extend credit to commercial customers Commitments To Extend Credit To Commercial Customers Commitments to extend credit to commercial customers. Reclassification from AOCI, current period, net of tax, attributable to parent Reclassification from AOCI, Current Period, Net of Tax, Attributable to Parent Schedule Of Equity Method Investments [Table] Equity Method Investment [Table] Accounting Policies [Abstract] Accounting Policies [Abstract] Equity securities, gross unrealized gains Equity Securities Gross Unrealized Gains Equity securities gross unrealized gains. Treasury Stock Treasury Stock, Common [Member] Year one Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year Pay vs Performance Disclosure [Line Items] Accruing Loans Past Due 90 Days or More Financial Asset, Equal to or Greater than 90 Days Past Due [Member] Preferred stock, liquidation preference per share (in USD per share) Preferred Stock, Liquidation Preference Per Share Line of Credit Facility, Lender [Domain] Line of Credit Facility, Lender [Domain] Liabilities Liabilities [Abstract] Divestiture Business Combination [Text Block] Net charge-offs Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff (Recovery) Automobile Automobile Loan [Member] Trading Activity, by Type Trading Activity, by Type [Domain] Debt Instrument, Redemption, Period Debt Instrument, Redemption, Period [Domain] Modified past due 30-89 days Delinquency Status of Loans and Leases Receivable Modified Past Due Thirty to Eighty Nine Days Delinquency status of loans and leases receivable modified past due thirty to eighty nine days. Variable Interest Entity [Table] Variable Interest Entity [Table] Year three Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year Statement of Cash Flows [Abstract] Statement of Cash Flows [Abstract] Company Selected Measure Amount Company Selected Measure Amount Prior Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year, Writeoff Total comprehensive income Total comprehensive income Comprehensive Income (Loss), Net of Tax, Attributable to Parent Measurement Input Type [Axis] Measurement Input Type [Axis] Name Measure Name Due in one year or less Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, Year One Total other comprehensive income (loss) Other Comprehensive Income (Loss), before Tax, Portion Attributable to Parent Net change in deposits Increase (Decrease) in Deposits Investment securities available for sale Proceeds from Maturities, Prepayments and Calls of Debt Securities, Available-for-Sale Class of Stock [Line Items] Class of Stock [Line Items] Renewable Energy Renewable Energy [Member] Renewable Energy Total debt securities estimated fair value Investment In Debt Securities Estimated Fair Value Investment in debt securities estimated fair value. Long-term borrowings (a) Total long-term borrowings Loan facility carrying amount Long-Term Debt Legal Entity [Axis] Legal Entity [Axis] Total assets Total assets of partnerships in which the company invested Assets Other Consumer, Other [Member] Financing Receivable, Credit Quality Indicator [Line Items] Financing Receivable, Credit Quality Indicator [Line Items] Interest Income Recognized Impaired Financing Receivable Nonaccrual Interest Income Impaired financing receivable nonaccrual interest income. Cash flows from operating activities Cash Provided by (Used in) Operating Activity, Including Discontinued Operation [Abstract] Net change in short-term borrowings Net Increase Decrease In Short Term Borrowings Net increase (decrease) in short term borrowings. 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Nonrecurring Fair Value, Nonrecurring [Member] Schedule Of Financing Receivable Troubled Debt Restructurings [Table] Financing Receivable, Modified [Table] Product and Service Product and Service [Domain] Interest received during the period Proceeds from Interest Received Restatement does not require Recovery Restatement Does Not Require Recovery [Text Block] Total liabilities Liabilities, Fair Value Disclosure Notional Amount Derivative, Notional Amount Organization, Consolidation and Presentation of Financial Statements [Abstract] Combination of Modification Types Combination of Modification Types [Member] Combination of modification types. Preferred Series H Series H Preferred Stock [Member] Revolving Loans Financing Receivable, Excluding Accrued Interest, Revolving Other assets for its "investment" in the common securities recognized by the company of various trusts Other Assets For Its Investment In Common Securities Recognized By Company Of Various Trusts Other assets for its "investment" in the common securities recognized by the company of various trusts. Computations of Diluted Earnings Per Common Share Schedule of Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Table Text Block] City Area Code City Area Code Changes in Allowance for Credit Losses Financing Receivable, Allowance for Credit Loss [Table Text Block] Award Timing, How MNPI Considered Award Timing, How MNPI Considered [Text Block] Total investment securities, less than 12 months, fair value Investment Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value This item represents the fair value of securities that have been in a continuous loss position for less than twelve months. Held-for-sale measurement input (as a percent) Loan, Held-for-Sale, Measurement Input Cash flows from investing activities Cash Provided by (Used in) Investing Activity, Including Discontinued Operation [Abstract] Maturity Period 2028 Maturity Period Four [Member] Maturity Period Four Fixed Rate Available For Sale Securities Fixed Rate Available For Sale Securities [Member] Fixed Rate Available For Sale Securities Pay vs Performance Disclosure Pay vs Performance Disclosure [Table] Guaranteed by Government-Related Entities Loans Insured or Guaranteed by US Government Authorities [Member] Home equity lines and loans Home Equity Lines And Loans [Member] Home equity lines and loans. Fair value hedges: Fair Value Hedging [Member] Investment securities Investment Securities Investment Securities Realized gain Debt Securities, Realized Gain (Loss) Amortization of net actuarial gain Defined Benefit Plan, Amortization of Gain (Loss) Total debt securities gross unrealized gains Investment In Debt Securities Gross Unrealized Gains Investment in debt securities gross unrealized gains. 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Commercial Real Estate Commercial Real Estate Portfolio Segment [Member] Unamortized loan cost (fee) and purchase premium (discount) Financing Receivable, Unamortized Loan Cost (Fee) and Purchase Premium (Discount) Entity [Domain] Entity [Domain] Net cash from investing activities Cash Provided by (Used in) Investing Activity, Including Discontinued Operation Period of satisfaction of contract with customer Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period Aggregate Change in Present Value of Accumulated Benefit for All Pension Plans Reported in Summary Compensation Table Aggregate Change in Present Value of Accumulated Benefit for All Pension Plans Reported in Summary Compensation Table [Member] Loans Insured or Guaranteed by Government Authorities [Axis] Loans Insured or Guaranteed by Government Authorities [Axis] Gain on disposition of business Gain (Loss) on Disposition of Business Interest paid during the period Interest Paid, Excluding Capitalized Interest, Operating Activity Document Fiscal Year Focus Document Fiscal Year Focus Basis of Accounting Basis of Accounting, Policy [Policy Text Block] Lender Name [Axis] Lender Name [Axis] Four Point Seven Six Two Percentage Fixed Rate Senior Notes Due To Mature In July 2027 Four Point Seven Six Two Percentage Fixed Rate Senior Notes Due To Mature In July 2027 [Member] Four Point Seven Six Two Percentage Fixed Rate Senior Notes Due To Mature In July 2027 All Other Other Operating Segment [Member] Carrying Amount Reported Value Measurement [Member] Preferred Series I Series I Preferred Stocks [Member] Series I preferred stocks Debt securities held to maturity: Debt Securities, Held-to-Maturity, Fair Value, Maturity [Abstract] Trust income Fiduciary and Trust [Member] Equity [Abstract] Equity [Abstract] Senior notes Senior Notes Gain (loss) on bank investment securities Debt and Equity Securities, Gain (Loss) Segment information Segment Reporting Disclosure [Text Block] Financial guarantees and indemnification contracts Commitments Regarding Financial Guarantees And Indemnification Contracts Commitments regarding financial guarantees and indemnification contracts. Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Not Designated as Hedging Instrument Not Designated as Hedging Instrument [Member] Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Outside data processing and software Information Technology and Data Processing Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss [Abstract] Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss [Abstract] Other Other Debt Obligations [Member] Compensation Actually Paid vs. Total Shareholder Return Compensation Actually Paid vs. Total Shareholder Return [Text Block] Bayview Lending Group Bayview Lending Group [Member] Bayview Lending Group. Comprehensive income Comprehensive Income (Loss) Note [Text Block] Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Table] Fair Value, Recurring and Nonrecurring [Table] Amortization of core deposit and other intangible assets Amortization of Intangible Assets Loans Proceeds from Sale of Loans Receivable Accumulated Other Comprehensive Income (Loss), Net Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Depreciation and amortization of premises and equipment Depreciation and amortization Depreciation, Depletion and Amortization Residential Residential Residential Mortgage-Backed Securities [Member] Revolving Loans Revolving Credit Facility [Member] Bayview Lending Group and Bayview Financial Bayview Lending Group And Bayview Financial [Member] Bayview Lending Group and Bayview Financial. 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Due after five years through ten years Debt Securities, Held-to-Maturity, Amortized Cost, after Allowance for Credit Loss, Maturity, Allocated and Single Maturity Date, after Year 5 through 10 Asset derivatives, fair value Derivative Asset, Subject to Master Netting Arrangement, before Offset Investment securities pledged to secure debt carrying value Carrying Value Of Investment Securities Pledged Carrying value of investment securities pledged. Entity Registrant Name Entity Registrant Name Impact of estimated fair value gain (losses) on hedging instruments Impact In Estimated Fair Value Gain Losses On Hedging Instruments Impact in estimated fair value gain (losses ) on hedging instruments. Stock Price or TSR Estimation Method Stock Price or TSR Estimation Method [Text Block] Net periodic benefit Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Residential Residential Real Estate Excluding Alt A [Member] Residential real estate excluding Alt-A. Trading Activity Trading Activity [Axis] Total assets Assets, Fair Value Disclosure Loan Modification Activities to Borrowers Experiencing Financial Difficulty on Financing Receivables Modifications to borrowers experiencing financial difficulty on financing receivables [Table Text Block] Modifications to borrowers experiencing financial difficulty on financing receivables. Schedule of Borrowings Schedule of Asset-Backed Notes Issued to Investors Schedule of Debt [Table Text Block] Interest cost on projected benefit obligation Defined Benefit Plan, Interest Cost HTM, less than 12 months, fair value Debt Securities, Held-to-Maturity, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value Restatement Determination Date: Restatement Determination Date [Axis] Accumulated Other Comprehensive Income Loss [Table] Accumulated Other Comprehensive Income (Loss) [Table] Components of Other Comprehensive Income (Loss) and Amounts Reclassified from Accumulated Other Comprehensive Income (Loss) to Net Income Components Of Other Comprehensive Income Loss [Table Text Block] The tabular disclosure of components of other comprehensive income loss. Information about Interest Rate Swap Agreements Schedule of Interest Rate Derivatives [Table Text Block] Provision for credit losses Financing Receivable And Unfunded Commitments, Excluding Accrued Interest, Credit Loss Expense (Reversal) Financing Receivable And Unfunded Commitments, Excluding Accrued Interest, Credit Loss Expense (Reversal) Other, net Proceeds from (Payment for) Other Financing Activity Change in fair value of nonrecurring fair value measured loans for charge-offs and impairment reserves Increase Decrease In Fair Value Of Nonrecurring Fair Value Measured Loans For Charge Offs And Impairment Reserves Increase (decrease) in fair value of nonrecurring fair value measured loans for charge offs and impairment reserve. Summary of loans in Accrual and Nonaccrual Status Summary Of Loans In Accrual And Nonaccrual Status [Table Text Block] Summary of loans in accrual and nonaccrual status. Name Trading Arrangement, Individual Name Foreign exchange and other option and futures contracts Foreign Exchange And Other Option And Futures Contracts [Member] Foreign exchange and other option and futures contracts. Real estate loans held for sale Loan, Held-for-Sale, Fair Value Disclosure Fixed Rate Long-Term Borrowings Fixed Rate Long Term Borrowings [Member] Fixed rate long-term borrowings. Asset-Backed Notes to Investors Debt Instrument, Face Amount Statement of Comprehensive Income [Abstract] Statement of Comprehensive Income [Abstract] Other commercial real estate Commitments To Extend Credit For Other Commercial Real Estate Commitments to extend credit for other commercial real estate. Other Accumulated Other [Member] Accumulated other. Preferred Stock Preferred Stock [Member] Name Awards Close in Time to MNPI Disclosures, Individual Name Due after one year through five years Debt Securities, Held-to-Maturity, Amortized Cost, after Allowance for Credit Loss, Maturity, Allocated and Single Maturity Date, after Year One through Five Aggregate Erroneous Compensation Not Yet Determined Aggregate Erroneous Compensation Not Yet Determined [Text Block] Outstanding balance Other Commitment Debt Securities, Available For Sale Debt Securities, Available For Sale [Member] Debt Securities, Available For Sale Amortized Cost and Estimated Fair Value of Investment Securities Amortized Cost And Estimated Fair Value Of Investment Securities [Table Text Block] Amortized cost and estimated fair value of investment securities. Treasury stock — common, at cost — 22,913,989 shares at June 30, 2025; 13,922,820 shares at December 31, 2024 Treasury Stock, Value Other comprehensive income (loss) before reclassifications, tax Other Comprehensive Income (Loss) before Reclassifications, Tax Segments Segments [Domain] Income Statement Location Statement of Income Location, Balance [Axis] Investment securities Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block] Fair Value Hierarchy and NAV Fair Value Hierarchy and NAV [Domain] Derivatives not designated as hedging instruments, derivatives Gain (Loss) on Derivative Instruments Held for Trading Purposes, Net Balance Sheet Location Statement of Financial Position Location, Balance [Domain] Investment Securities AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-Sale, Parent [Member] Interest expense Interest Expense, Operating and Nonoperating [Abstract] Relationship with BLG and Bayview Financial Relationship With Other Entities [Text Block] Relationship with other entities. Investment securities available for sale Payments to Acquire Debt Securities, Available-for-Sale Preferred stock Carrying Amount Preferred Stock, Value, Issued State and political subdivisions US States and Political Subdivisions Debt Securities [Member] Subordinated notes Subordinated Debt Year two Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year Short-term borrowings Debt, Current [Abstract] Weighted-average remaining term Loans and leases weighted-average remaining term Loans and leases weighted-average remaining term Unfunded commitments includes carrying amount of its investments Unfunded Commitments Includes Carrying Amount Of Its Investments Unfunded commitments includes carrying amount of its investments. Financial Asset, Aging [Axis] Financial Asset, Aging [Axis] All Executive Categories All Executive Categories [Member] Common stock, $0.50 par, 250,000,000 shares authorized, 179,436,779 shares issued at June 30, 2025 and December 31, 2024 Common Stock, Value, Issued Loans Interest and Fee Income, Loans and Leases Year one Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year, Writeoff Other Other Long-Term Debt Investment securities: Marketable Securities [Abstract] Interest Income Interest Income [Member] Ownership percentage (as a percent) Equity Method Investment, Ownership Percentage Change in cash flow hedges derivative instruments, fair value net Change in Cash Flow Hedges Derivative Instruments At Fair Value Net Change in Cash Flow Hedges Derivative Instruments At Fair Value Net Net income available to common shareholders Income available to common shareholders: Net Income (Loss) Available to Common Stockholders, Basic [Abstract] Common stock issuable (in shares) Common Stock Issuable Share Number of shares of common stock issuable in connection with deferred compensation plans. PEO Actually Paid Compensation Amount PEO Actually Paid Compensation Amount Due after ten years Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, after Year 10 Revenue from Contract with Customer [Abstract] Revenue from Contract with Customer [Abstract] Hedging Designation Hedging Designation [Axis] Other Other Interest and Dividend Income Allowance for credit losses Debt Securities, Held-to-Maturity, Allowance for Credit Loss M&T M And T [Member] M&T. Defined benefit plans liability adjustments Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax Cash flow hedge reclassification before tax Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, before Tax Derivative Contract Derivative Contract [Domain] Schedule Of Financing Receivable Allowance For Credit Losses [Table] Financing Receivable, Allowance for Credit Loss [Table] All Individuals All Individuals [Member] Fair Value Disclosures [Abstract] Fair Value Disclosures [Abstract] Name Forgone Recovery, Individual Name Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years That are Outstanding and Unvested Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years That are Outstanding and Unvested [Member] Weighted-Average Rate Debt, Weighted Average Interest Rate Year five Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year, Writeoff Debt Securities, Held-to-Maturity [Table] Debt Securities, Held-to-Maturity [Table] Erroneous Compensation Analysis Erroneous Compensation Analysis [Text Block] Fixed Derivative, Average Fixed Interest Rate Commercial and industrial Commercial Portfolio Segment [Member] Net change in other accrued income and expense Increase (Decrease) in Other Operating Assets and Liabilities, Net Rule 10b5-1 Arrangement Terminated Rule 10b5-1 Arrangement Terminated [Flag] Readily marketable securities gross unrealized losses Readily Marketable Securities At Fair Value Gross Unrealized Losses Readily marketable securities at fair value gross unrealized losses. Reserve for Unfunded Credit Commitments Reserve for Unfunded Credit Commitments [Member] Reserve for Unfunded Credit Commitments Erroneously Awarded Compensation Recovery Erroneously Awarded Compensation Recovery [Table] Title of 12(b) Security Title of 12(b) Security Provision for credit losses Financing Receivable, Excluding Accrued Interest, Credit Loss Expense (Reversal) Percentage loans in the process of foreclosure, serviced by other entities, classified as government guaranteed Percentage Of Loans In The Process Of Foreclosure Serviced By Other Entities Classified As Government Guaranteed Percentage of loans in the process of foreclosure, serviced by other entities, classified as government guaranteed. Defined contribution pension and retirement savings plans total expense Pension and Other Postretirement Benefits Cost (Reversal of Cost) Net income per common share Earnings Per Share [Abstract] Commitments to extend credit Commitments To Extend Credit, Amount Commitments To Extend Credit, Amount Other securities, amortized cost Other Investments and Securities, at Cost Year three Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year, Writeoff Maximum credit risk for recourse associated with loans sold under Federal National Mortgage Association Delegated Underwriting and Servicing program Maximum Credit Risk For Recourse Associated With Loans Sold Under Federal National Mortgage Association Delegated Underwriting And Servicing Program Maximum credit risk for recourse associated with loans sold under Federal National Mortgage Association Delegated Underwriting and Servicing program. Financing Receivable, Allowance for Credit Losses [Line Items] Financing Receivable, Allowance for Credit Loss [Line Items] Award Timing Disclosures [Line Items] Service cost Defined Benefit Plan, Service Cost Measurement Frequency Measurement Frequency [Domain] FHLBs Facility Federal Home Loan Bank Advances [Member] Shareholders' equity Equity [Text Block] Loan Restructuring Modification Loan Restructuring Modification [Domain] Net loans Net loans Financing Receivable, Excluding Accrued Interest, after Allowance for Credit Loss Net income Net income Net income (loss) Net Income (Loss) Attributable to Parent Readily marketable securities amortized cost Readily Marketable Securities At Fair Value Amortized Cost Readily marketable securities at fair value amortized cost. Clearinghouse Credit Facilities Clearinghouse Credit Facilities [Member] Clearinghouse credit facilities. Accounts Receivable, Allowance for Credit Loss [Roll Forward] Accounts Receivable, Allowance for Credit Loss [Roll Forward] Segment Reporting Information [Line Items] Segment Reporting Information [Line Items] Preferred stock, shares authorized (in shares) Preferred Stock, Shares Authorized Total investment securities, 12 months or longer, gross unrealized losses Investment Securities Continuous Unrealized Loss Position Twelve Months Or Longer Aggregate Losses Amount of accumulated unrealized loss on investments in debt and equity securities that have been in a continuous loss position for twelve months or longer. Purchases of treasury stock Payments for Repurchase of Common Stock Adoption Date Trading Arrangement Adoption Date Financing Receivable, Past Due [Table] Financing Receivable, Past Due [Table] Schedule Of Borrowings [Line Items] Schedule Of Borrowings [Line Items] Schedule of borrowings. Commercial and industrial Commercial Financial Leasing [Member] Commercial financial leasing. Retained earnings Retained Earnings (Accumulated Deficit) Residential Real Estate Residential Portfolio Segment [Member] Year-end Fair Value of Equity Awards Granted in Covered Year that are Outstanding and Unvested Year-end Fair Value of Equity Awards Granted in Covered Year that are Outstanding and Unvested [Member] Affordable Housing Projects Affordable Housing Projects [Member] Affordable Housing Projects Maturity Period 2027 Maturity Period Three [Member] Maturity Period Three [Member]. Criticized nonaccrual Criticized Nonaccrual [Member] Criticized nonaccrual. Investment securities in held-to-maturity portfolio securitized by Bayview Financial Debt Security, Mortgage-Backed, Held-to-Maturity, Fair Value Disclosure Class of Stock Class of Stock [Axis] Cash Flow Hedges Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent [Member] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Brokerage services income Brokerage Commissions Revenue Outstanding principal balances of residential mortgage loans from Bayview Financial Sub Serviced Residential Mortgage Loans Of Privately Held Company Outstanding principal balance of sub-serviced residential real estate loans for a privately-held specialty mortgage finance company. Aggregate Grant Date Fair Value of Equity Award Amounts Reported in Summary Compensation Table Aggregate Grant Date Fair Value of Equity Award Amounts Reported in Summary Compensation Table [Member] Retirement Plan Type Retirement Plan Type [Axis] Statement [Table] Statement [Table] Provision for deferred income taxes Deferred Income Tax Expense (Benefit) Adjustments to reconcile net income to net cash provided by operating activities: Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity [Abstract] Cash flows from financing activities Cash Provided by (Used in) Financing Activity, Including Discontinued Operation [Abstract] Contract with customer Contract with Customer, Liability Debt securities available for sale: Debt Securities, Available-for-Sale, Amortized Cost, Fiscal Year Maturity [Abstract] Commitments to sell real estate loans Commitments To Sell Real Estate Loans Notional Amount Commitments to sell real estate loans notional amount. Net (gain) loss on sales of assets Gain (Loss) on Disposition of Assets for Financial Service Operations All Adjustments to Compensation All Adjustments to Compensation [Member] Other (a) Contractual Interest Rate Reduction [Member] Total available for held to maturity (fair value) Debt Securities, Held-to-Maturity, Maturity, Allocated and Single Maturity Date, Fair Value Amendment flag Amendment Flag Debt securities available for sale: Debt Securities, Available-for-Sale, Fair Value, Fiscal Year Maturity [Abstract] Other Postretirement Benefits Other Postretirement Benefits Plan [Member] Termination Date Trading Arrangement Termination Date Interest-bearing deposits at banks Interest-Bearing Deposits in Banks and Other Financial Institutions Insider Trading Policies and Procedures Adopted Insider Trading Policies and Procedures Adopted [Flag] Contingent commitments to provide additional capital contributions to partnerships Contingent Commitments to Provide Additional Capital Contributions to Partnerships Contingent Commitments to Provide Additional Capital Contributions to Partnerships Long-term borrowings Long-Term Debt, Excluding Current Maturities [Abstract] Allowance for loan losses Beginning balance Ending balance Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest Basic (in shares) Weighted-average shares outstanding (in shares) Weighted Average Number of Shares Outstanding, Basic Segment Reporting [Abstract] Segment Reporting [Abstract] Debt Disclosure [Abstract] Debt Disclosure [Abstract] Reclassification from AOCI, current period, tax Reclassification from AOCI, Current Period, Tax Taxable-equivalent adjustment Taxable Equivalent Adjustment Taxable equivalent adjustment. Amounts reclassified from accumulated other comprehensive income (loss) that (increase) decrease net income: Reclassification from AOCI, Current Period, before Tax, Attributable to Parent Defined benefit plan, net periodic benefit cost (credit) excluding service cost, statement of income or comprehensive income [extensible enumeration] Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Excluding Service Cost, Statement of Income or Comprehensive Income [Extensible Enumeration] Total available for held to maturity (amortized cost) Held To Maturity Securities Debt Maturities With Single Maturity Date Net Carrying Amount Carrying amount of debt securities accounted for as held-to-maturity, net of adjustments including, but not limited to, accretion, amortization, collection of cash, previous other-than-temporary impairments (OTTI) recognized, and fair value hedge accounting adjustments, that have single maturity date. Readily marketable securities estimated fair value Readily Marketable Securities At Estimated Fair Value Readily marketable securities at estimated fair value. Forgone Recovery due to Expense of Enforcement, Amount Forgone Recovery due to Expense of Enforcement, Amount Common stock issuable, 9,556 shares at June 30, 2025; 11,642 shares at December 31, 2024 Common Stock Issuable The obligation to issue shares of company common stock in connection with deferred compensation plans. Common stock par value (in USD per share) Common Stock, Par or Stated Value Per Share Consolidated Entities Consolidated Entities [Axis] Trading account Trading Account Trading account. Amortized Cost with Allowance Financing Receivable, Excluding Accrued Interest, Nonaccrual, With Allowance Financing Receivable, Excluding Accrued Interest, Nonaccrual, With Allowance Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items] Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items] Financing receivable, modifications other than troubled debt restructuring. Equipment and net occupancy Occupancy, Net Less: Income attributable to unvested stock-based compensation awards Income Attributable To Unvested Stock Based Compensation Awards Diluted Income attributable to unvested stock based compensation awards. This amount is used as a reduction to net income available to common equity in the calculation of net income available to common shareholders as used in the determination of diluted earnings per share. Other Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax Insider Trading Arrangements [Line Items] Prior Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year Current Financial Asset, Not Past Due [Member] Other Product and Service, Other [Member] Total liabilities Liabilities Five Point One Seven Nine Percentage Fixed Rate Senior Notes Due To Mature In July 2030 Five Point One Seven Nine Percentage Fixed Rate Senior Notes Due To Mature In July 2030 [Member] Five Point One Seven Nine Percentage Fixed Rate Senior Notes Due To Mature In July 2030 Total available for sale (amortized cost) Debt Securities, Available-for-Sale, Maturity, Allocated and Single Maturity Date, Amortized Cost Percent of Total Loan Class Financing Receivable, Excluding Accrued Interest, Modified in Period, to Total Financing Receivables, Percentage Preferred Series G Series G Preferred Stock [Member] Pension Adjustments Prior Service Cost Pension Adjustments Prior Service Cost [Member] Material Terms of Trading Arrangement Material Terms of Trading Arrangement [Text Block] Net change in loans Payments for (Proceeds from) Loans and Leases Net income available to common equity Net Income Loss Available To Common Stockholders Basic Before Unvested Stock Based Compensation Awards Adjustment Net income loss available to common stockholders before unvested stock based compensation awards adjustment as used in the determination of basic earnings per common share. Amount of foreclosed residential real estate property held Other Real Estate, Foreclosed Assets, and Repossessed Assets Issuance of Series J preferred stock Stock Issued During Period, Value, New Issues Intersegment Activity Eliminated in Consolidated Totals Consolidation Items [Axis] Counterparty Name [Axis] Counterparty Name [Axis] Investment securities held to maturity Proceeds from Maturities, Prepayments and Calls of Held-to-Maturity Securities Deposits at banks Interest Income, Domestic Deposits Available for sale (cost: $21,458 at June 30, 2025; $19,054 at December 31, 2024) Investment securities available for sale, estimated fair value Investment securities available for sale, estimated fair value Debt Securities, Available-for-Sale Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Carrying value of investment securities pledged related to repurchase transactions Carrying Value of Investment Securities Pledged Related to Repurchase Transactions Carrying value of investment securities pledged related to repurchase transactions.. Non-NEOs Non-NEOs [Member] Amount of initial margin posted Collateral Already Posted, Aggregate Fair Value