v3.26.3
DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES (Derivative Gain (Loss) Recognized/Reclassified) (Details) - USD ($)
$ in Millions
 3 Months Ended 9 Months Ended
Sep. 30, 2026
Sep. 30, 2025
Sep. 30, 2026
Sep. 30, 2025
Derivative Instruments, Gain (Loss) [Line Items]        
Amount of gain/(loss) reclassified from AOCI into income $ 37 $ (11) $ 66 $ (45)
Loss to be reclassified within the next 12 months into interest income     85 37
Deferred losses 12   12  
Derivatives designated as accounting hedges:        
Derivative Instruments, Gain (Loss) [Line Items]        
Effective portion of derivative gain/(loss) deferred in AOCI (59) 0 (120) 8
Amount of gain/(loss) reclassified from AOCI into income (12) (15) (34) (52)
Interest on fair value hedges 3 12 10 34
Derivatives designated as accounting hedges: | Cash Flow Hedging        
Derivative Instruments, Gain (Loss) [Line Items]        
Terminated or redesignated, unamortized basis adjustments, debt 26 34 26 34
Terminated or redesignated, unamortized basis adjustments, assets 2 3 2 3
Derivatives designated as accounting hedges: | Cash Flow Hedging | Hedges of floating-rate assets        
Derivative Instruments, Gain (Loss) [Line Items]        
Effective portion of derivative gain/(loss) deferred in AOCI (59) 0 (120) 8
Amount of gain/(loss) reclassified from AOCI into income (12) (15) (34) (53)
Interest on fair value hedges 0 0 0 0
Derivatives designated as accounting hedges: | Cash Flow Hedging | Hedges of floating-rate liabilities        
Derivative Instruments, Gain (Loss) [Line Items]        
Effective portion of derivative gain/(loss) deferred in AOCI 0 0 0 0
Amount of gain/(loss) reclassified from AOCI into income 0 0 0 1
Interest on fair value hedges 0 0 0 0
Derivatives designated as accounting hedges: | Fair Value Hedging | Hedges of fixed-rate assets        
Derivative Instruments, Gain (Loss) [Line Items]        
Effective portion of derivative gain/(loss) deferred in AOCI 0 0 0 0
Amount of gain/(loss) reclassified from AOCI into income 0 0 0 0
Interest on fair value hedges 5 15 16 42
Derivatives designated as accounting hedges: | Fair Value Hedging | Hedges of fixed-rate liabilities        
Derivative Instruments, Gain (Loss) [Line Items]        
Effective portion of derivative gain/(loss) deferred in AOCI 0 0 0 0
Amount of gain/(loss) reclassified from AOCI into income 0 0 0 0
Interest on fair value hedges (2) (3) (6) (8)
Derivatives not designated as hedging instruments        
Derivative Instruments, Gain (Loss) [Line Items]        
Interest on fair value hedges 36 7 70 38
Hedge ineffectiveness (1) 0 (2) 0
Derivatives not designated as hedging instruments | Cash Flow Hedging | Hedges of floating-rate assets        
Derivative Instruments, Gain (Loss) [Line Items]        
Hedge ineffectiveness 0 0 0 0
Derivatives not designated as hedging instruments | Cash Flow Hedging | Hedges of floating-rate liabilities        
Derivative Instruments, Gain (Loss) [Line Items]        
Hedge ineffectiveness 0 0 0 0
Derivatives not designated as hedging instruments | Fair Value Hedging | Hedges of fixed-rate assets        
Derivative Instruments, Gain (Loss) [Line Items]        
Hedge ineffectiveness (1) 0 (1) 0
Derivatives not designated as hedging instruments | Fair Value Hedging | Hedges of fixed-rate liabilities        
Derivative Instruments, Gain (Loss) [Line Items]        
Hedge ineffectiveness $ 0 $ 0 $ (1) $ 0