v3.26.3
BORROWINGS - Long-term Borrowings - Narrative (Details) - USD ($)
1 Months Ended 3 Months Ended 9 Months Ended
Oct. 31, 2026
Sep. 30, 2026
Sep. 30, 2025
Sep. 30, 2026
Sep. 30, 2025
Aug. 03, 2026
Jun. 24, 2026
Mar. 03, 2026
Dec. 31, 2025
Debt Instrument [Line Items]                  
Loss on extinguishment of debt   $ (19,000,000) $ 0 $ (34,000,000) $ 0        
Minimum deposit   $ 163,000,000   163,000,000         $ 212,000,000
Fixed-to-Floating Senior Notes at 5.097% | Subordinated Debt                  
Debt Instrument [Line Items]                  
Debt instrument, face amount           $ 400,000,000 $ 750,000,000    
Debt instrument, stated interest rate             5.097%    
Fixed-to-Floating Senior Notes | Subordinated Debt                  
Debt Instrument [Line Items]                  
Debt instrument, face amount               $ 500,000,000  
Purchase Money Note                  
Debt Instrument [Line Items]                  
Partial prepayment       $ 13,000,000,000.00          
Purchase Money Note | Subsequent Event                  
Debt Instrument [Line Items]                  
Partial prepayment $ 1,500,000,000                
Parent | Fixed-to-Floating Senior Notes | Subordinated Debt                  
Debt Instrument [Line Items]                  
Debt instrument, stated interest rate               4.869%