Name:	mtb_BusinessAcquisitionPurchasePriceAllocationCertainLoansAcquiredAtFairValue
Namespace Prefix:	mtb_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Amount of contractual cash flows not expected to be collected at acquisition of acquired loans with evidence of deterioration of credit quality.

No definition available.

Name:	mtb_CertainLoansAcquiredDuringPeriodContractualCashFlowsNotExpectedToBeCollectedAtAcquisition
Namespace Prefix:	mtb_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Amount of contractually required principal and interest at acquisition of acquired loans with evidence of deterioration of credit quality.

No definition available.

Name:	mtb_CertainLoansAcquiredDuringPeriodContractuallyRequiredPrincipalAndInterestAtAcquisition
Namespace Prefix:	mtb_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Amount of the interest component of expected cash flows at acquisition of acquired loans with evidence of deterioration of credit quality.

No definition available.

Name:	mtb_CertainLoansAcquiredDuringPeriodInterestComponentOfExpectedCashFlowsAtAcquisition
Namespace Prefix:	mtb_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Amount of cash flows expected to be collected at acquisition of acquired loans accounted for as debt securities with evidence of deterioration of credit quality.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 30
-Section 15
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=27045933&loc=d3e13503-111538

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=6379141&loc=d3e15032-111544

Name:	us-gaap_CertainLoansAcquiredInTransferAccountedForAsDebtSecuritiesAcquiredDuringPeriodCashFlowsExpectedToBeCollectedAtAcquisition
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

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.

No definition available.