Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2023	May 01, 2023
Document Information [Line Items]
Document Type	10-Q/A
Amendment Flag	true
Amendment Description	This Amendment No. 1 amends M&T Bank Corporation’s Quarterly Report on Form 10-Q for the quarterly period ended March 31, 2023, which was filed on May 5, 2023. This Amendment No. 1 is being filed on May 15, 2023 solely for the purpose of correcting a typographical error in Item 1, note 12 of Notes to Financial Statements – Fair Value Measurements in the table included within the "Disclosures of fair value of financial instruments" section on page 38. The estimated fair value of time deposits in the table presenting the carrying amounts and estimated fair value, in thousands, for financial instrument assets (liabilities) as of March 31, 2023 was incorrectly presented without parentheses. The parentheses have been added for time deposits in both the Estimated Fair Value column and the Level 2 column and correctly presented as $(12,808,615) in each column. Except for these corrections, there have been no changes in any of the financial information or other information contained in the original Form 10-Q. This Amendment No. 1 speaks as of the original filing date of the Form 10-Q and does not reflect events that may have occurred subsequent to the original filing date.
Document Period End Date	Mar. 31, 2023
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q1
Entity Registrant Name	M&T BANK CORPORATION
Entity Central Index Key	0000036270
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		165,869,832
Entity File Number	1-9861
Entity Tax Identification Number	16-0968385
Entity Incorporation, State or Country Code	NY
Entity Address, Address Line One	One M & T Plaza
Entity Address, Postal Zip Code	14203
Entity Address, City or Town	Buffalo
Entity Address, State or Province	NY
City Area Code	716
Local Phone Number	635-4000
Document Quarterly Report	true
Document Transition Report	false
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Shell Company	false
Common Stock [Member]
Document Information [Line Items]
Trading Symbol	MTB
Title of 12(b) Security	Common Stock, $.50 par value
Security Exchange Name	NYSE
Series H Preferred Stock [Member]
Document Information [Line Items]
Trading Symbol	MTBPrH
Title of 12(b) Security	Perpetual Fixed-to-Floating RateNon-Cumulative Preferred Stock, Series H
Security Exchange Name	NYSE