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v3.24.1.u1

Segment Information - Information about Company's Segments (Parenthetical) (Detail) - USD ($) $ in Millions | 3 Months Ended
--- | ---
Mar. 31, 2024 | Mar. 31, 2023
Segment Reporting Information [Line Items] |  |
Taxable-equivalent adjustment | $ 12 | $ 14

X
- Definition Taxable equivalent adjustment. + References No definition available. + Details
Name: | mtb_TaxableEquivalentAdjustment
Namespace Prefix: | mtb_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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 No definition available. + Details
Name: | us-gaap_SegmentReportingInformationLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration