v3.26.1
Document and Entity Information - shares
 3 Months Ended
Mar. 31, 2026
Apr. 30, 2026
Document Information [Line Items]    
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Mar. 31, 2026  
Entity File Number 1-9861  
Entity Registrant Name M&T BANK CORPORATION  
Entity Incorporation, State or Country Code NY  
Entity Tax Identification Number 16-0968385  
Entity Address, Address Line One One M&T Plaza  
Entity Address, City or Town Buffalo  
Entity Address, State or Province NY  
Entity Address, Postal Zip Code 14203  
City Area Code 716  
Local Phone Number 635-4000  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Large Accelerated Filer  
Entity Small Business false  
Entity Emerging Growth Company false  
Entity Shell Company false  
Entity Common Stock, Shares Outstanding   146,445,060
Entity Central Index Key 0000036270  
Document Fiscal Year Focus 2026  
Document Fiscal Period Focus Q1  
Amendment flag false  
Current Fiscal Year End Date --12-31  
Document Transition Report false  
Common Stock    
Document Information [Line Items]    
Title of 12(b) Security Common Stock, $0.50 par value  
Trading Symbol MTB  
Security Exchange Name NYSE  
Preferred Series H    
Document Information [Line Items]    
Title of 12(b) Security Perpetual Fixed-to-Floating RateNon-Cumulative Preferred Stock, Series H  
Trading Symbol MTBPrH  
Security Exchange Name NYSE  
Preferred Series J    
Document Information [Line Items]    
Title of 12(b) Security Perpetual Fixed Rate Non-CumulativePreferred Stock, Series J  
Trading Symbol MTBPrJ  
Security Exchange Name NYSE  
Preferred Series K    
Document Information [Line Items]    
Title of 12(b) Security Perpetual Fixed Rate Non-CumulativePreferred Stock, Series K  
Trading Symbol MTBPrK  
Security Exchange Name NYSE