XML 78 R67.htm IDEA: XBRL DOCUMENT
v3.25.2

Derivative financial instruments - Information about Interest Rate Swap Agreements (Detail) - USD ($) $ in Millions | 6 Months Ended | 12 Months Ended
--- | --- | ---
Jun. 30, 2025 | Dec. 31, 2024
Derivative [Line Items] |  |
Notional Amount | $ 32,750 | $ 36,184
Weighted-Average Maturity (In years) | 2 years 3 months 18 days | 2 years 2 months 12 days
Estimated fair value gain (loss) | $ 24 | $ (1)
Fair value hedges: |  |
Derivative [Line Items] |  |
Impact of estimated fair value gain (losses) on hedging instruments | (20) | (153)
Fair value hedges: | Forward-Starting Interest Rate Swap Agreements |  |
Derivative [Line Items] |  |
Notional Amount | 2,800 | 3,400
Cash flow hedges: |  |
Derivative [Line Items] |  |
Impact of estimated fair value gain (losses) on hedging instruments | 74 | (136)
Cash flow hedges: | Forward-Starting Interest Rate Swap Agreements |  |
Derivative [Line Items] |  |
Notional Amount | 11,500 | 10,000
Interest Payments On Variable Rate Commercial Real Estate Loans | Cash flow hedges: |  |
Derivative [Line Items] |  |
Notional Amount | $ 26,650 | $ 30,819
Weighted-Average Maturity (In years) | 1 year 7 months 6 days | 1 year 7 months 6 days
Fixed | 3.59% | 3.41%
Variable | 4.32% | 4.47%
Estimated fair value gain (loss) | $ 11 | $ 1
Fixed Rate Long-Term Borrowings | Fair value hedges: |  |
Derivative [Line Items] |  |
Notional Amount | $ 6,100 | $ 5,350
Weighted-Average Maturity (In years) | 5 years 3 months 18 days | 5 years 10 months 24 days
Fixed | 3.56% | 3.55%
Variable | 4.46% | 4.71%
Estimated fair value gain (loss) | $ 13 | $ (2)
Fixed Rate Available For Sale Securities | Fair value hedges: |  |
Derivative [Line Items] |  |
Notional Amount |  | $ 15
Weighted-Average Maturity (In years) |  | 1 month 6 days
Fixed |  | 4.84%
Variable |  | 4.36%
Estimated fair value gain (loss) |  | $ 0

X
- Definition Impact in estimated fair value gain (losses ) on hedging instruments. + References No definition available. + Details
Name: | mtb_ImpactInEstimatedFairValueGainLossesOnHedgingInstruments
Namespace Prefix: | mtb_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Average fixed interest rate related to the group of interest rate derivatives. + References No definition available. + Details
Name: | us-gaap_DerivativeAverageFixedInterestRate
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Average remaining period until maturity of the derivative contract, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References No definition available. + Details
Name: | us-gaap_DerivativeAverageRemainingMaturity1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Average variable interest rate related to the group of interest rate derivatives. + References No definition available. + Details
Name: | us-gaap_DerivativeAverageVariableInterestRate
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 815 -SubTopic 20 -Name Accounting Standards Codification -Section 25 -Paragraph 6A -Publisher FASB -URI https://asc.fasb.org/1943274/2147480682/815-20-25-6A Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 815 -SubTopic 40 -Name Accounting Standards Codification -Section 50 -Paragraph 5 -Subparagraph (f) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480237/815-40-50-5 + Details
Name: | us-gaap_DerivativeLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Nominal or face amount used to calculate payment on derivative. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 55 -Paragraph 181 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480401/815-10-55-181 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 1B -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-1B Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 1A -Subparagraph (d) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-1A + Details
Name: | us-gaap_DerivativeNotionalAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amount of unrealized gain (loss) related to the fair value of interest rate derivatives designated as fair value hedging instruments, as offset by the gain (loss) on the hedged item to the extent that the fair value hedge is determined to be effective. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4A -Subparagraph (b)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4A Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4C -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4C + Details
Name: | us-gaap_IncreaseDecreaseInFairValueOfInterestRateFairValueHedgingInstruments1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis=us-gaap_FairValueHedgingMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=mtb_ForwardStartingInterestRateSwapAgreementsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis=us-gaap_CashFlowHedgingMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=mtb_InterestPaymentsOnVariableRateCommercialRealEstateLoansMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_TradingActivityByTypeAxis=mtb_FixedRateLongTermBorrowingsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_TradingActivityByTypeAxis=mtb_FixedRateAvailableForSaleSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |