Loans and Leases - Summary of Lease Financing Receivables (Detail) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Financing:
Lease payments receivable	$ 2,431	$ 2,175
Estimated residual value of leased assets	274	262
Unearned income	(248)	(145)
Investment in financing leases	2,457	2,292
Leveraged:
Lease payments receivable	57	71
Estimated residual value of leased assets	52	74
Unearned income	(15)	(22)
Investment in leveraged leases	94	123
Total investment in leases	2,551	2,415
Deferred taxes payable arising from leveraged leases	$ 36	$ 52

Finance leases net investment in direct financing leases unearned income.

No definition available.

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

- Definition

Net investment in direct financing and leveraged type leases.

+ References

No definition available.

+ Details

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

- References

No definition available.

+ Details

Name:	us-gaap_CapitalLeasesNetInvestmentInDirectFinancingLeasesAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Present value of lease payments not yet received by lessor and amount expected to be derived from underlying asset, following end of lease term, guaranteed by lessee or other third party unrelated to lessor, from direct financing lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 842
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479773/842-30-50-6

+ Details

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

- Definition

Amount, before allowance for credit loss, of net investment in direct financing lease.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479344/326-20-45-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 14
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479319/326-20-50-14

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 842
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479773/842-30-50-6

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Name Accounting Standards Codification
-Section 50
-Paragraph 7A
-SubTopic 10
-Topic 310
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481962/310-10-50-7A

+ Details

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

- Definition

Present value expected to be derived from underlying asset, following end of lease term, not guaranteed by lessee or other third party unrelated to lessor.

+ References

+ Details

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

- Definition

The estimated portion of pretax income and investment tax credit remaining to be allocated to income over the lease term.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 842
-SubTopic 50
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479711/842-50-50-1

Reference 2: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Topic 840
-SubTopic 30
-Name Accounting Standards Codification
-Section 30
-Paragraph 14
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481274/840-30-30-14

+ Details

Name:	us-gaap_LeveragedLeasesNetInvestmentInLeveragedLeasesDisclosureDeferredIncome
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Taxes arising from arrangements meeting the criteria for classification as leveraged leases due to timing differences between accounting and tax income recognition.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 842
-SubTopic 50
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479711/842-50-50-1

Reference 2: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Topic 840
-SubTopic 30
-Name Accounting Standards Codification
-Section 45
-Paragraph 5
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481192/840-30-45-5

+ Details

Name:	us-gaap_LeveragedLeasesNetInvestmentInLeveragedLeasesDisclosureDeferredTaxesArisingFromLeveragedLeases
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The net investment in arrangements meeting the criteria for classification as leveraged leases including deferred taxes.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 842
-SubTopic 50
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479711/842-50-50-1

Reference 2: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Topic 840
-SubTopic 30
-Name Accounting Standards Codification
-Section 30
-Paragraph 14
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481274/840-30-30-14

+ Details

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

- References

No definition available.

+ Details

Name:	us-gaap_LeveragedLeasesNetInvestmentInLeveragedLeasesDisclosureInvestmentInLeveragedLeasesNetAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

This element represents leveraged lease rentals receivable, net of that portion of the rental applicable to principal and interest on the nonrecourse debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 842
-SubTopic 50
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479711/842-50-50-1

Reference 2: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Topic 840
-SubTopic 30
-Name Accounting Standards Codification
-Section 30
-Paragraph 14
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481274/840-30-30-14

+ Details

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

- Definition

The estimate of the value of the leased asset at the end of the lease term.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 842
-SubTopic 50
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479711/842-50-50-1

Reference 2: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Topic 840
-SubTopic 30
-Name Accounting Standards Codification
-Section 30
-Paragraph 14
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481274/840-30-30-14

+ Details

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