Derivative Financial Instruments - Notional Amount of Interest Rate Swap Agreements Outstanding Maturity (Detail) - Interest Rate Swap Agreements [Member]	Dec. 31, 2016 USD ($)
Derivative Instruments And Hedging Activities Disclosures [Line Items]
2017	$ 400,000,000
2018	500,000,000
Total	$ 900,000,000

Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 12
-Section 13
-Sentence Column B

+ Details

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Namespace Prefix:	invest_
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Balance Type:	na
Period Type:	instant

- Definition

The notional amount of interest rate swap agreements entered into for risk management purposes that mature in next twelve months after the balance sheet date.

+ References

No definition available.

+ Details

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

- Definition

The notional amount of interest rate swap agreements entered into for risk management purposes that mature during the second year after the balance sheet date.

+ References

No definition available.

+ Details

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

- 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

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
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- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_InterestRateSwapMember
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