Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2019	Jul. 31, 2019
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q2
Trading Symbol	MTB
Entity Registrant Name	M&T BANK CORP
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		133,666,679
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity File Number	1-9861
Entity Tax Identification Number	160968385
Entity Address, Address Line One	One M & T Plaza
Entity Address, City or Town	Buffalo
Entity Address, State or Province	New York
Entity Address, Postal Zip Code	14203
City Area Code	716
Local Phone Number	635-4000