Acquisitions - Consideration Paid for Acquired Identifiable Assets and Liabilities (Parenthetical) (Detail) (Wilmington Trust Corporation [Member]) In Thousands, unless otherwise specified	May 16, 2011
Wilmington Trust Corporation [Member]
Business Acquisition [Line Items]
Common shares issued	4,694,486

Business Acquisition Cost Of Acquired Entity Number Of Shares Of Common Stock Issued

No definition available.

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Namespace Prefix:	mtb_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant