v3.26.1
CREDIT QUALITY AND THE ALLOWANCE FOR CREDIT LOSSES - Troubled Debt Restructurings, Modified Default (Details) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Financing Receivable, Modified, Subsequent Default [Line Items]    
Amortized cost basis of modified loans that are in subsequent default $ 84 $ 82
Interest Rate Reduction    
Financing Receivable, Modified, Subsequent Default [Line Items]    
Amortized cost basis of modified loans that are in subsequent default 1 2
Term Extension    
Financing Receivable, Modified, Subsequent Default [Line Items]    
Amortized cost basis of modified loans that are in subsequent default 77 76
Payment Delay    
Financing Receivable, Modified, Subsequent Default [Line Items]    
Amortized cost basis of modified loans that are in subsequent default 1 1
Interest Rate Reduction and Term Extension    
Financing Receivable, Modified, Subsequent Default [Line Items]    
Amortized cost basis of modified loans that are in subsequent default 3 3
Term Extension and Payment Delay    
Financing Receivable, Modified, Subsequent Default [Line Items]    
Amortized cost basis of modified loans that are in subsequent default 1  
Interest Rate Reduction, Term Extension and Payment Delay    
Financing Receivable, Modified, Subsequent Default [Line Items]    
Amortized cost basis of modified loans that are in subsequent default 1  
Commercial    
Financing Receivable, Modified, Subsequent Default [Line Items]    
Amortized cost basis of modified loans that are in subsequent default 69 71
Commercial | Interest Rate Reduction    
Financing Receivable, Modified, Subsequent Default [Line Items]    
Amortized cost basis of modified loans that are in subsequent default 0 0
Commercial | Term Extension    
Financing Receivable, Modified, Subsequent Default [Line Items]    
Amortized cost basis of modified loans that are in subsequent default 69 71
Commercial | Payment Delay    
Financing Receivable, Modified, Subsequent Default [Line Items]    
Amortized cost basis of modified loans that are in subsequent default 0 0
Commercial | Interest Rate Reduction and Term Extension    
Financing Receivable, Modified, Subsequent Default [Line Items]    
Amortized cost basis of modified loans that are in subsequent default 0 0
Commercial | Term Extension and Payment Delay    
Financing Receivable, Modified, Subsequent Default [Line Items]    
Amortized cost basis of modified loans that are in subsequent default 0  
Commercial | Interest Rate Reduction, Term Extension and Payment Delay    
Financing Receivable, Modified, Subsequent Default [Line Items]    
Amortized cost basis of modified loans that are in subsequent default 0  
Commercial | Commercial and industrial    
Financing Receivable, Modified, Subsequent Default [Line Items]    
Amortized cost basis of modified loans that are in subsequent default 0 0
Commercial | Commercial and industrial | Interest Rate Reduction    
Financing Receivable, Modified, Subsequent Default [Line Items]    
Amortized cost basis of modified loans that are in subsequent default 0 0
Commercial | Commercial and industrial | Term Extension    
Financing Receivable, Modified, Subsequent Default [Line Items]    
Amortized cost basis of modified loans that are in subsequent default 0 0
Commercial | Commercial and industrial | Payment Delay    
Financing Receivable, Modified, Subsequent Default [Line Items]    
Amortized cost basis of modified loans that are in subsequent default 0 0
Commercial | Commercial and industrial | Interest Rate Reduction and Term Extension    
Financing Receivable, Modified, Subsequent Default [Line Items]    
Amortized cost basis of modified loans that are in subsequent default 0 0
Commercial | Commercial and industrial | Term Extension and Payment Delay    
Financing Receivable, Modified, Subsequent Default [Line Items]    
Amortized cost basis of modified loans that are in subsequent default 0  
Commercial | Commercial and industrial | Interest Rate Reduction, Term Extension and Payment Delay    
Financing Receivable, Modified, Subsequent Default [Line Items]    
Amortized cost basis of modified loans that are in subsequent default 0  
Commercial | Commercial real estate    
Financing Receivable, Modified, Subsequent Default [Line Items]    
Amortized cost basis of modified loans that are in subsequent default 69 71
Commercial | Commercial real estate | Interest Rate Reduction    
Financing Receivable, Modified, Subsequent Default [Line Items]    
Amortized cost basis of modified loans that are in subsequent default 0 0
Commercial | Commercial real estate | Term Extension    
Financing Receivable, Modified, Subsequent Default [Line Items]    
Amortized cost basis of modified loans that are in subsequent default 69 71
Commercial | Commercial real estate | Payment Delay    
Financing Receivable, Modified, Subsequent Default [Line Items]    
Amortized cost basis of modified loans that are in subsequent default 0 0
Commercial | Commercial real estate | Interest Rate Reduction and Term Extension    
Financing Receivable, Modified, Subsequent Default [Line Items]    
Amortized cost basis of modified loans that are in subsequent default 0 0
Commercial | Commercial real estate | Term Extension and Payment Delay    
Financing Receivable, Modified, Subsequent Default [Line Items]    
Amortized cost basis of modified loans that are in subsequent default 0  
Commercial | Commercial real estate | Interest Rate Reduction, Term Extension and Payment Delay    
Financing Receivable, Modified, Subsequent Default [Line Items]    
Amortized cost basis of modified loans that are in subsequent default 0  
Retail    
Financing Receivable, Modified, Subsequent Default [Line Items]    
Amortized cost basis of modified loans that are in subsequent default 15 11
Retail | Interest Rate Reduction    
Financing Receivable, Modified, Subsequent Default [Line Items]    
Amortized cost basis of modified loans that are in subsequent default 1 2
Retail | Term Extension    
Financing Receivable, Modified, Subsequent Default [Line Items]    
Amortized cost basis of modified loans that are in subsequent default 8 5
Retail | Payment Delay    
Financing Receivable, Modified, Subsequent Default [Line Items]    
Amortized cost basis of modified loans that are in subsequent default 1 1
Retail | Interest Rate Reduction and Term Extension    
Financing Receivable, Modified, Subsequent Default [Line Items]    
Amortized cost basis of modified loans that are in subsequent default 3 3
Retail | Term Extension and Payment Delay    
Financing Receivable, Modified, Subsequent Default [Line Items]    
Amortized cost basis of modified loans that are in subsequent default 1  
Retail | Interest Rate Reduction, Term Extension and Payment Delay    
Financing Receivable, Modified, Subsequent Default [Line Items]    
Amortized cost basis of modified loans that are in subsequent default 1  
Retail | Residential mortgages    
Financing Receivable, Modified, Subsequent Default [Line Items]    
Amortized cost basis of modified loans that are in subsequent default 14 8
Retail | Residential mortgages | Interest Rate Reduction    
Financing Receivable, Modified, Subsequent Default [Line Items]    
Amortized cost basis of modified loans that are in subsequent default 0 0
Retail | Residential mortgages | Term Extension    
Financing Receivable, Modified, Subsequent Default [Line Items]    
Amortized cost basis of modified loans that are in subsequent default 8 5
Retail | Residential mortgages | Payment Delay    
Financing Receivable, Modified, Subsequent Default [Line Items]    
Amortized cost basis of modified loans that are in subsequent default 1 1
Retail | Residential mortgages | Interest Rate Reduction and Term Extension    
Financing Receivable, Modified, Subsequent Default [Line Items]    
Amortized cost basis of modified loans that are in subsequent default 3 2
Retail | Residential mortgages | Term Extension and Payment Delay    
Financing Receivable, Modified, Subsequent Default [Line Items]    
Amortized cost basis of modified loans that are in subsequent default 1  
Retail | Residential mortgages | Interest Rate Reduction, Term Extension and Payment Delay    
Financing Receivable, Modified, Subsequent Default [Line Items]    
Amortized cost basis of modified loans that are in subsequent default 1  
Retail | Home equity    
Financing Receivable, Modified, Subsequent Default [Line Items]    
Amortized cost basis of modified loans that are in subsequent default 0 2
Retail | Home equity | Interest Rate Reduction    
Financing Receivable, Modified, Subsequent Default [Line Items]    
Amortized cost basis of modified loans that are in subsequent default 0 1
Retail | Home equity | Term Extension    
Financing Receivable, Modified, Subsequent Default [Line Items]    
Amortized cost basis of modified loans that are in subsequent default 0 0
Retail | Home equity | Payment Delay    
Financing Receivable, Modified, Subsequent Default [Line Items]    
Amortized cost basis of modified loans that are in subsequent default 0 0
Retail | Home equity | Interest Rate Reduction and Term Extension    
Financing Receivable, Modified, Subsequent Default [Line Items]    
Amortized cost basis of modified loans that are in subsequent default 0 1
Retail | Home equity | Term Extension and Payment Delay    
Financing Receivable, Modified, Subsequent Default [Line Items]    
Amortized cost basis of modified loans that are in subsequent default 0  
Retail | Home equity | Interest Rate Reduction, Term Extension and Payment Delay    
Financing Receivable, Modified, Subsequent Default [Line Items]    
Amortized cost basis of modified loans that are in subsequent default 0  
Retail | Education    
Financing Receivable, Modified, Subsequent Default [Line Items]    
Amortized cost basis of modified loans that are in subsequent default 0 0
Retail | Education | Interest Rate Reduction    
Financing Receivable, Modified, Subsequent Default [Line Items]    
Amortized cost basis of modified loans that are in subsequent default 0 0
Retail | Education | Term Extension    
Financing Receivable, Modified, Subsequent Default [Line Items]    
Amortized cost basis of modified loans that are in subsequent default 0 0
Retail | Education | Payment Delay    
Financing Receivable, Modified, Subsequent Default [Line Items]    
Amortized cost basis of modified loans that are in subsequent default 0 0
Retail | Education | Interest Rate Reduction and Term Extension    
Financing Receivable, Modified, Subsequent Default [Line Items]    
Amortized cost basis of modified loans that are in subsequent default 0 0
Retail | Education | Term Extension and Payment Delay    
Financing Receivable, Modified, Subsequent Default [Line Items]    
Amortized cost basis of modified loans that are in subsequent default 0  
Retail | Education | Interest Rate Reduction, Term Extension and Payment Delay    
Financing Receivable, Modified, Subsequent Default [Line Items]    
Amortized cost basis of modified loans that are in subsequent default 0  
Retail | Other retail    
Financing Receivable, Modified, Subsequent Default [Line Items]    
Amortized cost basis of modified loans that are in subsequent default 1 1
Retail | Other retail | Interest Rate Reduction    
Financing Receivable, Modified, Subsequent Default [Line Items]    
Amortized cost basis of modified loans that are in subsequent default 1 1
Retail | Other retail | Term Extension    
Financing Receivable, Modified, Subsequent Default [Line Items]    
Amortized cost basis of modified loans that are in subsequent default 0 0
Retail | Other retail | Payment Delay    
Financing Receivable, Modified, Subsequent Default [Line Items]    
Amortized cost basis of modified loans that are in subsequent default 0 0
Retail | Other retail | Interest Rate Reduction and Term Extension    
Financing Receivable, Modified, Subsequent Default [Line Items]    
Amortized cost basis of modified loans that are in subsequent default 0 $ 0
Retail | Other retail | Term Extension and Payment Delay    
Financing Receivable, Modified, Subsequent Default [Line Items]    
Amortized cost basis of modified loans that are in subsequent default 0  
Retail | Other retail | Interest Rate Reduction, Term Extension and Payment Delay    
Financing Receivable, Modified, Subsequent Default [Line Items]    
Amortized cost basis of modified loans that are in subsequent default $ 0