Segment information - Additional Information (Detail)	12 Months Ended
Dec. 31, 2012
Segment Reporting Information [Line Items]
Percent of maximum revenue from single customer on total revenues	10.00%

Percent of maximum revenue from single customer on total revenue.

No definition available.

Name:	mtb_PercentOfMaximumRevenueFromSingleCustomerOnRevenue
Namespace Prefix:	mtb_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration