v3.26.1
BORROWINGS - Schedule of Long-term Borrowings (Details) - USD ($)
$ in Millions
3 Months Ended
Mar. 31, 2026
Mar. 03, 2026
Dec. 31, 2025
Debt Instrument [Line Items]      
Capital lease obligations $ 73   $ 72
Total long-term borrowings $ 33,792   35,784
Parent | Fixed-to-Floating Senior Notes at 5.231% | Senior Notes      
Debt Instrument [Line Items]      
Debt instrument, stated interest rate 5.231%    
Long-term debt, gross $ 497   497
Basis spread on variable rate 1.41%    
Parent | Fixed-to-Floating Senior Notes at 4.869% | Senior Notes      
Debt Instrument [Line Items]      
Debt instrument, stated interest rate 4.869%    
Long-term debt, gross $ 495   0
Parent | Fixed-to-Floating Senior Notes at 4.869% | Subordinated Debt      
Debt Instrument [Line Items]      
Debt instrument, stated interest rate   4.869%  
Basis spread on variable rate 1.487%    
Parent | Fixed-to-Fixed Subordinated Notes at 5.600% | Subordinated Debt      
Debt Instrument [Line Items]      
Debt instrument, stated interest rate 5.60%    
Long-term debt, gross $ 595   597
Basis spread on variable rate 1.85%    
Parent | Fixed-to-Fixed Subordinated Notes at 6.254% | Subordinated Debt      
Debt Instrument [Line Items]      
Debt instrument, stated interest rate 6.254%    
Long-term debt, gross $ 742   745
Basis spread on variable rate 1.97%    
Subsidiaries | Fixed Senior Unsecured Notes at 6.000% | Senior Notes      
Debt Instrument [Line Items]      
Debt instrument, stated interest rate 6.00%    
Long-term debt, gross $ 58   58
Subsidiaries | Fixed Subordinated Notes at 6.125% | Subordinated Debt      
Debt Instrument [Line Items]      
Debt instrument, stated interest rate 6.125%    
Long-term debt, gross $ 427   430
Subsidiaries | Purchase Money Note to FDIC fixed at 3.500% | Secured Debt      
Debt Instrument [Line Items]      
Debt instrument, stated interest rate 3.50%    
Long-term debt, gross $ 30,905   33,385
Debt instrument, unamortized discount $ 95   $ 115