Basis spread on variable rate EBP, Participant Loan, Basis Spread On Variable Rate EBP, Participant Loan, Basis Spread On Variable Rate Entity tax identification number Entity Tax Identification Number Vested percentage EBP, Employer Contribution Vesting Percentage EBP, Employer Contribution Vesting Percentage Vesting service EBP, Employer Contribution Vesting Service Period EBP, Employer Contribution Vesting Service Period Maximum Maximum [Member] Legal Entity [Axis] Legal Entity [Axis] Statistical Measurement [Domain] Statistical Measurement [Domain] EBP, Description of Plan [Table] EBP, Description of Plan [Table] Mutual funds Mutual Fund [Member] EBP, Employer Contribution, Tranche Three EBP, Employer Contribution, Tranche Three [Member] EBP, Employer Contribution, Tranche Three Sales EBP, Investment Sold, Excluding Plan Interest in Master Trust, Selling Price EBP, Related Party and Party-in-Interest Transactions [Table] EBP, Related Party and Party-in-Interest Transactions [Table] Maximum annual compensation to total compensation percentage EBP, Participant Contribution, Pretax, Maximum Annual Compensation to Total Compensation, Percentage EBP, Fully Benefit-Responsive Investment Contract [Table] EBP, Fully Benefit-Responsive Investment Contract [Table] Involuntary cash-out limit EBP, Involuntary Cash-out Limit EBP, Involuntary Cash-out Limit Maximum borrowing, amount EBP, Note Receivable from Participant, Account, Maximum Borrowing, Amount Fair value measurements EBP, Investment, Fair Value and NAV [Text Block] Minimum borrowing, amount EBP, Note Receivable from Participant, Account, Minimum Borrowing, Amount EBP, Fully Benefit-Responsive Investment Contract [Abstract] Investments, at fair value EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value Level 1 Fair Value, Inputs, Level 1 [Member] Investment contracts EBP, Fully Benefit-Responsive Investment Contract [Text Block] EBP, Investment, Fair Value and NAV [Abstract] EBP, Employer Contribution, Tranche Five EBP, Employer Contribution, Tranche Five [Member] EBP, Employer Contribution, Tranche Five EBP, Employer Contribution, Vesting [Axis] EBP, Employer Contribution, Vesting [Axis] EBP, Employer Contribution, Vesting Schedule of Related Party and Party-in-Interest Transactions EBP, Related Party and Party-in-Interest Transactions [Table Text Block] Investments EBP, Asset [Abstract] Statistical Measurement [Axis] Statistical Measurement [Axis] Additions EBP, Change in Net Asset Available for Benefit, Increase [Abstract] EBP, Statement of Change in Net Asset Available for Benefit [Table] EBP, Statement of Change in Net Asset Available for Benefit [Table] Participant benefits and withdrawals EBP, Payment to Participant [Policy Text Block] Amendment Flag Amendment Flag Basis of accounting EBP, Basis of Accounting [Policy Text Block] EBP, Schedule of Asset Held for Investment [Table] EBP, Schedule of Asset Held for Investment [Table] Due from broker EBP, Investment Sale, Receivable Investment, number of shares (in shares) EBP, Investment, Number of Shares EBP, Description of Plan and Accounting Change [Abstract] Receivables EBP, Receivable [Abstract] EBP, Investment, Fair Value and NAV EBP, Investment, Fair Value and NAV [Table Text Block] M&T Bank Corporation common stock Common Stock [Member] Investments [Domain] Investments [Domain] Use of estimates EBP, Use of Estimate [Policy Text Block] Schedule H, Line 4i – Schedule of Assets (Held At End of Year) EBP, Schedule of Asset Held for Investment [Text Block] Cover [Abstract] EBP, Employer Contribution, Tranche Two EBP, Employer Contribution, Tranche Two [Member] EBP, Employer Contribution, Tranche Two Risks and uncertainties EBP, Risk and Uncertainty [Text Block] Employer – Matching EBP, Change in Net Asset Available for Benefit, Increase from Employer Contribution, Cash Minimum investment program percentage EBP, Minimum Investment Program Percentage EBP, Minimum Investment Program Percentage Minimum Minimum [Member] Investment Type [Axis] Investment Type [Axis] Interest income on notes receivable from participants EBP, Change in Net Asset Available for Benefit, Increase from Interest Income on Note Receivable from Participant Total contributions EBP, Change in Net Asset Available for Benefit, Increase from Contribution Participants EBP, Change in Net Asset Available for Benefit, Increase from Participant Contribution, Excluding Rollover Net appreciation in fair value of investments EBP, Change in Net Asset Available for Benefit, Increase (Decrease) from Gain (Loss) on Investment Interest and dividends EBP, Change in Net Asset Available for Benefit, Increase from Interest and Dividend Income on Investment EBP, Description of Plan [Line Items] EBP, Description of Plan [Line Items] Plan number EBP, Plan Number EBP, Investment, Fair Value and NAV [Line Items] EBP, Investment, Fair Value and NAV [Line Items] Description of plan EBP, Description of Plan [Text Block] EBP 004 EBP 004 [Member] EBP 004 EBP, Statement of Change in Net Asset Available for Benefit [Line Items] EBP, Statement of Change in Net Asset Available for Benefit [Line Items] EBP, Statement of Net Asset Available for Benefit [Table] EBP, Statement of Net Asset Available for Benefit [Table] Employer – Discretionary EBP, Change In Net Asset Available For Benefit, Increase From Employer Discretionary Contribution, Cash EBP, Change In Net Asset Available For Benefit, Increase From Employer Discretionary Contribution, Cash EBP, Schedule of Asset Held for Investment [Line Items] EBP, Schedule of Asset Held for Investment [Line Items] EBP, Employer Contribution, Tranche Four EBP, Employer Contribution, Tranche Four [Member] EBP, Employer Contribution, Tranche Four EBP, Employer, Common Stock EBP, Employer, Common Stock [Member] EBP, Schedule of Asset Held for Investment [Abstract] EBP, Accounting Policy [Table] EBP, Accounting Policy [Table] Total additions EBP, Change in Net Asset Available for Benefit, Increase Investment income EBP, Change in Net Asset Available for Benefit, Increase (Decrease) from Income (Loss) on Investment [Abstract] Investment, Identifier [Axis] Investment, Identifier [Axis] Total investments EBP, Asset Held for Investment Document Information [Line Items] Document Information [Line Items] EBP, Risk and Uncertainty [Line Items] EBP, Risk and Uncertainty [Line Items] EBP, Risk and Uncertainty [Table] EBP, Risk and Uncertainty [Table] Realized gains EBP, Change in Net Asset Available for Benefit, Increase (Decrease) from Realized Gain (Loss) on Investment Participant compensation matched, percentage EBP, Employer Contribution, Participant Compensation Matched, Percentage EBP, Statement of Change in Net Asset Available for Benefit [Abstract] Level 2 Fair Value, Inputs, Level 2 [Member] Employer Contribution, Vesting EBP, Employer Contribution, Vesting [Table Text Block] EBP, Employer Contribution, Vesting EBP, Fully Benefit-Responsive Investment Contract [Line Items] EBP, Fully Benefit-Responsive Investment Contract [Line Items] EBP, Tax Status [Table] EBP, Tax Status [Table] Change in net assets available for benefits EBP, Change in Net Asset Available for Benefit, Increase (Decrease) Related-party transactions and party in interest EBP, Related Party and Party-in-Interest Transactions [Text Block] EBP, Related Party and Party-in-Interest Transactions [Abstract] EBP, Accounting Policy, Accounting Standard Update, and Change in Accounting Principle [Abstract] Total receivables EBP, Receivable Employer – Matching contribution EBP, Employer Contribution, Receivable Unrealized gains EBP, Change in Net Asset Available for Benefit, Increase (Decrease) from Unrealized Gain (Loss) on Investment Automatic deferral rate EBP, Participant Contribution, Automatic, Deferral Rate Investments EBP, Investment, Fair Value [Abstract] Cash dividends received EBP, Change in Net Asset Available for Benefit, Increase from Dividend Income on Investment Participant withdrawals and distributions EBP, Change in Net Asset Available for Benefit, Decrease from Payment to Participant Current value EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] EBP, Statement of Net Asset Available for Benefit [Abstract] EBP, Accounting Policy [Line Items] EBP, Accounting Policy [Line Items] EBP, Tax Status [Abstract] Synthetic investment contracts, minimum credit rating (as a percent) EBP, Synthetic Investment Contracts, Minimum Credit Rating, Percent EBP, Synthetic Investment Contracts, Minimum Credit Rating, Percent Administrative expenses EBP, Expense [Policy Text Block] EBP, Employer Contribution, Tranche One EBP, Employer Contribution, Tranche One [Member] EBP, Employer Contribution, Tranche One Participant Loans Receivable EBP, Asset Held for Investment, Participant Loan, after Deemed Distribution Investment valuation and income recognition EBP, Investment [Policy Text Block] Participant contributions EBP, Participant Contribution, Receivable Fair Value, Inputs, Level 1, Level 2, and Level 3 Fair Value, Inputs, Level 1, Level 2, and Level 3 [Member] Document Type Document Type Entity Central Index Key Entity Central Index Key Participant loan interest rate EBP, Asset Held for Investment, Participant Loan, Interest Rate Common Collective Trust Common Collective Trust [Member] Synthetic investment contracts, average yield (as a percent) EBP, Synthetic Investment Contracts, Average Yield, Percent EBP, Synthetic Investment Contracts, Average Yield, Percent EBP, Tax Status [Line Items] EBP, Tax Status [Line Items] EBP, Risk and Uncertainty [Abstract] EBP, Subsequent Event [Table] EBP, Subsequent Event [Table] Participant compensation matched, minimum service period EBP, Requisite Service Period EBP, Requisite Service Period Deductions EBP, Change in Net Asset Available for Benefit, Decrease [Abstract] Forfeited nonvested account, decrease from employer contribution EBP, Forfeited Nonvested Account, Decrease from Employer Contribution Notes receivable from participants EBP, Note Receivable from Participant Requisite service hours EBP, Requisite Minimum Service Hours EBP, Requisite Minimum Service Hours Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Summary of significant accounting policies EBP, Summary of Accounting Policy [Text Block] Entity Registrant Name Entity Registrant Name Purchases EBP, Investment Acquired, Excluding Plan Interest in Master Trust, Cost EBP, Subsequent Event [Abstract] Subsequent events EBP, Subsequent Event [Text Block] General loan administrative fee EBP, Note Receivable From Participant, General Loan, Administrative Fee EBP, Note Receivable From Participant, General Loan, Administrative Fee General loan, borrowing term EBP, Note Receivable From Participant, General Loan, Maximum Borrowing Term EBP, Note Receivable From Participant, General Loan, Maximum Borrowing Term Automatic deferral rate, annual increase EBP, Participant Contribution, Automatic, Annual Increase Deferral Rate EBP, Participant Contribution, Automatic, Annual Increase Deferral Rate Income taxes EBP, Tax Status [Text Block] EBP, Employer Contribution, Vesting [Domain] EBP, Employer Contribution, Vesting [Domain] EBP, Employer Contribution, Vesting [Domain] Maximum borrowing, to total account, percentage EBP, Note Receivable from Participant, Account, Maximum Borrowing, to Total Account, Percentage EBP, Subsequent Event [Line Items] EBP, Subsequent Event [Line Items] Employer – retirement accumulation Account contribution EBP, Employer Contribution, Retirement Accumulation Account Receivable EBP, Employer Contribution, Retirement Accumulation Account Receivable Document Information [Table] Document Information [Table] Notes receivable from participants EBP, Note Receivable from Participant [Policy Text Block] Total investment income EBP, Change in Net Asset Available for Benefit, Increase (Decrease) from Income (Loss) on Investment EBP, Related Party and Party-in-Interest Transactions [Line Items] EBP, Related Party and Party-in-Interest Transactions [Line Items] Level 3 Fair Value, Inputs, Level 3 [Member] Net assets available for benefits Beginning of year End of year EBP, Net Asset Available for Benefit Total investments EBP, Investment, Excluding Plan Interest in Master Trust, Fair and Contract Value Entity [Domain] Entity [Domain] Contributions EBP, Change in Net Asset Available for Benefit, Increase from Contribution [Abstract] Investments, at contract value EBP, Investment, Excluding Plan Interest in Master Trust, Contract Value Matching percentage EBP, Employer Contribution, Matching Percentage NAV Fair Value Measured at Net Asset Value Per Share [Member] EBP, Investment, Fair Value and NAV [Table] EBP, Investment, Fair Value and NAV [Table] Employer – Retirement Accumulation Account EBP, Change In Net Asset Available For Benefit, Increase From Employer Retirement Accumulation Account Contribution, Cash EBP, Change In Net Asset Available For Benefit, Increase From Employer Retirement Accumulation Account Contribution, Cash EBP, Statement of Net Asset Available for Benefit [Line Items] EBP, Statement of Net Asset Available for Benefit [Line Items]