XML 141 R122.htm IDEA: XBRL DOCUMENT
v3.25.0.1

Comprehensive Income - Components of Other Comprehensive Income (Loss) and Amounts Reclassified from Accumulated Other Comprehensive Income (Loss) to Net Income (Detail) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022
AOCI Attributable to Parent, Net of Tax [Roll Forward] |  |  |
Beginning balance | $ 26,957 | $ 25,318 | $ 17,903
Other comprehensive income before reclassifications: |  | 125 |
Other comprehensive income (loss) before reclassifications, tax |  | (33) |
OCI, before reclassifications, net of tax, attributable to parent |  | 92 |
Ending balance | 29,027 | 26,957 | 25,318
AOCI Attributable to Parent |  |  |
AOCI Attributable to Parent, Net of Tax [Roll Forward] |  |  |
Equity, attributable to parent, beginning balance | (616) | (1,066) | (171)
Beginning balance | 157 | 276 | 44
Beginning balance | (459) | (790) | (127)
Other comprehensive income before reclassifications: | 37 | 207 | (949)
Other comprehensive income (loss) before reclassifications, tax | (8) | (55) | 246
OCI, before reclassifications, net of tax, attributable to parent | 29 | 152 | (703)
Total other comprehensive income (loss) | 397 | 450 | (895)
Deferred income taxes and tax credits | (102) | (119) | 232
Other comprehensive income (loss), net of tax, portion attributable to parent | 295 | 331 | (663)
Equity, attributable to parent, ending balance | (219) | (616) | (1,066)
Ending balance | 55 | 157 | 276
Ending balance | (164) | (459) | (790)
Investment Securities |  |  |
AOCI Attributable to Parent, Net of Tax [Roll Forward] |  |  |
Equity, attributable to parent, beginning balance | (251) | (444) | 105
Beginning balance | (187) | (329) | 78
Other comprehensive income before reclassifications: | 31 | 193 | (551)
Other comprehensive income (loss) before reclassifications, tax | (8) | (51) | 143
OCI, before reclassifications, net of tax, attributable to parent | 23 | 142 | (408)
Amounts reclassified from accumulated other comprehensive income that (increase) decrease net income: | 15 |  | 2
Amortization of prior service credit, tax | (4) |  | (1)
Reclassification from AOCI, current period, net of tax, attributable to parent | 11 |  | 1
Total other comprehensive income (loss) | 46 | 193 | (549)
Equity, attributable to parent, ending balance | (205) | (251) | (444)
Ending balance | (153) | (187) | (329)
Cash Flow Hedges |  |  |
AOCI Attributable to Parent, Net of Tax [Roll Forward] |  |  |
Equity, attributable to parent, beginning balance | (203) | (337) | 88
Beginning balance | (151) | (249) | 66
Other comprehensive income before reclassifications: | (296) | (116) | (461)
Other comprehensive income (loss) before reclassifications, tax | 77 | 30 | 119
OCI, before reclassifications, net of tax, attributable to parent | (219) | (86) | (342)
Amounts reclassified from accumulated other comprehensive income that (increase) decrease net income: | 364 | 250 | 36
Amortization of prior service credit, tax | (95) | (66) | (9)
Reclassification from AOCI, current period, net of tax, attributable to parent | 269 | 184 | 27
Total other comprehensive income (loss) | 68 | 134 | (425)
Equity, attributable to parent, ending balance | (135) | (203) | (337)
Ending balance | (101) | (151) | (249)
Defined Benefit Plans |  |  |
AOCI Attributable to Parent, Net of Tax [Roll Forward] |  |  |
Equity, attributable to parent, beginning balance | (155) | (273) | (360)
Beginning balance | (115) | (202) | (267)
Other comprehensive income before reclassifications: | 305 | 125 | 71
Other comprehensive income (loss) before reclassifications, tax | (78) |  | (18)
OCI, before reclassifications, net of tax, attributable to parent | 227 |  | 53
Total other comprehensive income (loss) | 286 | 118 | 87
Equity, attributable to parent, ending balance | 131 | (155) | (273)
Ending balance | 98 | (115) | (202)
Prior Service Credit |  |  |
AOCI Attributable to Parent, Net of Tax [Roll Forward] |  |  |
Amounts reclassified from accumulated other comprehensive income that (increase) decrease net income: | (2) | (2) | (2)
Amortization of prior service credit, tax | 1 | 1 | 0
Reclassification from AOCI, current period, net of tax, attributable to parent | (1) | (1) | (2)
Actuarial Gains |  |  |
AOCI Attributable to Parent, Net of Tax [Roll Forward] |  |  |
Amounts reclassified from accumulated other comprehensive income that (increase) decrease net income: | (5) | (5) | 18
Amortization of prior service credit, tax | 1 | 1 | (4)
Reclassification from AOCI, current period, net of tax, attributable to parent | (4) | (4) | 14
Settlement gain |  |  |
AOCI Attributable to Parent, Net of Tax [Roll Forward] |  |  |
Amounts reclassified from accumulated other comprehensive income that (increase) decrease net income: | 12 |  |
Amortization of prior service credit, tax | 3 |  |
Reclassification from AOCI, current period, net of tax, attributable to parent | 9 |  |
Other |  |  |
AOCI Attributable to Parent, Net of Tax [Roll Forward] |  |  |
Equity, attributable to parent, beginning balance | (7) | (12) | (4)
Beginning balance | (6) | (10) | (4)
Other comprehensive income before reclassifications: | (3) | 5 | (8)
Other comprehensive income (loss) before reclassifications, tax | 1 | (1) | 2
OCI, before reclassifications, net of tax, attributable to parent | (2) | 4 | (6)
Total other comprehensive income (loss) | (3) | 5 | (8)
Equity, attributable to parent, ending balance | (10) | (7) | (12)
Ending balance | $ (8) | $ (6) | $ (10)

X
- Definition Equity, Attributable to Parent, Before Tax + References No definition available. + Details
Name: | mtb_EquityAttributableToParentBeforeTax
Namespace Prefix: | mtb_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Equity, Attributable To Parent, Tax + References No definition available. + Details
Name: | mtb_EquityAttributableToParentTax
Namespace Prefix: | mtb_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period. + References No definition available. + Details
Name: | us-gaap_AOCIAttributableToParentNetOfTaxRollForward
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of deferred income tax expense (benefit) and income tax credits. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 230 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 28 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482740/230-10-45-28 + Details
Name: | us-gaap_DeferredIncomeTaxesAndTaxCredits
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount before tax and reclassification adjustments of other comprehensive income (loss) attributable to parent. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 14A -Publisher FASB -URI https://asc.fasb.org/1943274/2147482790/220-10-45-14A + Details
Name: | us-gaap_OciBeforeReclassificationsBeforeTaxAttributableToParent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount after tax, before reclassification adjustments, of other comprehensive income (loss), attributable to parent. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 14A -Publisher FASB -URI https://asc.fasb.org/1943274/2147482790/220-10-45-14A Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 55 -Paragraph 15 -SubTopic 10 -Topic 220 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482739/220-10-55-15 + Details
Name: | us-gaap_OciBeforeReclassificationsNetOfTaxAttributableToParent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of tax expense (benefit) allocated to other comprehensive income (loss) before reclassification adjustment from accumulated other comprehensive income (loss). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 45 -Paragraph 12 -SubTopic 10 -Topic 220 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482790/220-10-45-12 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 220 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482765/220-10-50-4 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 220 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04(19)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147477250/944-220-S99-1 + Details
Name: | us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount before tax of other comprehensive income (loss) attributable to parent entity. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 810 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 19 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481231/810-10-45-19 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 45 -Paragraph 20 -SubTopic 10 -Topic 810 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481231/810-10-45-20 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 50 -Paragraph 1A -Subparagraph (c)(3) -SubTopic 10 -Topic 810 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481203/810-10-50-1A + Details
Name: | us-gaap_OtherComprehensiveIncomeLossBeforeTaxPortionAttributableToParent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount after tax of other comprehensive income (loss) attributable to parent entity. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 810 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 19 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481231/810-10-45-19 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 45 -Paragraph 20 -SubTopic 10 -Topic 810 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481231/810-10-45-20 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 50 -Paragraph 1A -Subparagraph (c)(3) -SubTopic 10 -Topic 810 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481203/810-10-50-1A Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 250 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 6 -Publisher FASB -URI https://asc.fasb.org/1943274/2147483443/250-10-50-6 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Topic 220 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 1B -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482790/220-10-45-1B Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Topic 220 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 1A -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482790/220-10-45-1A + Details
Name: | us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount before tax of reclassification adjustments of other comprehensive income (loss) attributable to parent. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 14A -Publisher FASB -URI https://asc.fasb.org/1943274/2147482790/220-10-45-14A + Details
Name: | us-gaap_ReclassificationFromAociCurrentPeriodBeforeTaxAttributableToParent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount after tax of reclassification adjustments of other comprehensive income (loss) attributable to parent. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 14A -Publisher FASB -URI https://asc.fasb.org/1943274/2147482790/220-10-45-14A Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 55 -Paragraph 15 -SubTopic 10 -Topic 220 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482739/220-10-55-15 + Details
Name: | us-gaap_ReclassificationFromAociCurrentPeriodNetOfTaxAttributableToParent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of tax expense (benefit) of reclassification adjustment from accumulated other comprehensive income (loss). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 45 -Paragraph 12 -SubTopic 10 -Topic 220 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482790/220-10-45-12 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 220 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482765/220-10-50-4 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 220 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04(19)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147477250/944-220-S99-1 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 220 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 17A -Publisher FASB -URI https://asc.fasb.org/1943274/2147482790/220-10-45-17A + Details
Name: | us-gaap_ReclassificationFromAociCurrentPeriodTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of equity (deficit) attributable to parent. Excludes temporary equity and equity attributable to noncontrolling interest. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(29)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(30)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(31)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1 Reference 4: http://www.xbrl.org/2003/role/exampleRef -Topic 852 -SubTopic 10 -Name Accounting Standards Codification -Section 55 -Paragraph 10 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481372/852-10-55-10 Reference 5: http://www.xbrl.org/2003/role/exampleRef -Topic 946 -SubTopic 830 -Name Accounting Standards Codification -Section 55 -Paragraph 12 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479168/946-830-55-12 Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Topic 946 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.6-04(19)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479170/946-210-S99-1 Reference 7: http://www.xbrl.org/2003/role/disclosureRef -Topic 946 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 2 -Subparagraph (SX 210.6-05(4)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479170/946-210-S99-2 Reference 8: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 946 -SubTopic 220 -Name Accounting Standards Codification -Section S99 -Paragraph 3 -Subparagraph (SX 210.6-09(4)(b)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479134/946-220-S99-3 Reference 9: http://www.xbrl.org/2003/role/disclosureRef -Topic 946 -SubTopic 220 -Name Accounting Standards Codification -Section S99 -Paragraph 3 -Subparagraph (SX 210.6-09(6)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479134/946-220-S99-3 Reference 10: http://www.xbrl.org/2003/role/disclosureRef -Topic 946 -SubTopic 220 -Name Accounting Standards Codification -Section S99 -Paragraph 3 -Subparagraph (SX 210.6-09(7)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479134/946-220-S99-3 Reference 11: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 235 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08(g)(1)(ii)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480678/235-10-S99-1 Reference 12: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 323 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481687/323-10-50-3 Reference 13: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 825 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 28 -Subparagraph (f) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482907/825-10-50-28 Reference 14: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 310 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 2 -Subparagraph (SAB Topic 4.E) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480418/310-10-S99-2 + Details
Name: | us-gaap_StockholdersEquity
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=us-gaap_AccumulatedOtherComprehensiveIncomeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetPriorServiceCostCreditMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetUnamortizedGainLossMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=mtb_AccumulatedDefinedBenefitPlansAdjustmentSettlementGainAttributableToParentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=mtb_AccumulatedOtherMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |