v3.26.1
Derivative Instruments and Hedging Activities - Schedule of Derivative Instruments Designated as Fair Value Hedges, Gain (Loss) (Details) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Derivative Instruments, Gain (Loss) [Line Items]    
Interest and fees on finance receivables and loans $ 2,658 $ 2,709
Interest and dividends on investment securities and other earning assets 234 230
Interest on long-term debt 265 271
Loss on cash flow hedges to be recognized within twelve months 3  
Total derivatives designated as accounting hedges | Interest and fees on finance receivables and loans    
Derivative Instruments, Gain (Loss) [Line Items]    
Total gain on fair value hedging relationships 0 0
Total loss on cash flow hedging relationships (5) (7)
Total derivatives designated as accounting hedges | Interest and dividends on investment securities and other earning assets    
Derivative Instruments, Gain (Loss) [Line Items]    
Total gain on fair value hedging relationships 0 0
Total loss on cash flow hedging relationships 0 0
Total derivatives designated as accounting hedges | Interest on long-term debt    
Derivative Instruments, Gain (Loss) [Line Items]    
Total gain on fair value hedging relationships 0 0
Total loss on cash flow hedging relationships 0 0
Total derivatives designated as accounting hedges | Hedged available-for-sale securities | Interest and fees on finance receivables and loans    
Derivative Instruments, Gain (Loss) [Line Items]    
Change in unrealized gain (loss) on hedged item in fair value hedge 0 0
Change in unrealized gain (loss) on fair value hedging instruments 0 0
Total derivatives designated as accounting hedges | Hedged available-for-sale securities | Interest and dividends on investment securities and other earning assets    
Derivative Instruments, Gain (Loss) [Line Items]    
Change in unrealized gain (loss) on hedged item in fair value hedge (77) 130
Change in unrealized gain (loss) on fair value hedging instruments 77 (130)
Total derivatives designated as accounting hedges | Hedged available-for-sale securities | Interest on long-term debt    
Derivative Instruments, Gain (Loss) [Line Items]    
Change in unrealized gain (loss) on hedged item in fair value hedge 0 0
Change in unrealized gain (loss) on fair value hedging instruments 0 0
Total derivatives designated as accounting hedges | Fixed-rate automotive loans | Interest and fees on finance receivables and loans    
Derivative Instruments, Gain (Loss) [Line Items]    
Change in unrealized gain (loss) on hedged item in fair value hedge (30) 29
Change in unrealized gain (loss) on fair value hedging instruments 30 (29)
Total derivatives designated as accounting hedges | Fixed-rate automotive loans | Interest and dividends on investment securities and other earning assets    
Derivative Instruments, Gain (Loss) [Line Items]    
Change in unrealized gain (loss) on hedged item in fair value hedge 0 0
Change in unrealized gain (loss) on fair value hedging instruments 0 0
Total derivatives designated as accounting hedges | Fixed-rate automotive loans | Interest on long-term debt    
Derivative Instruments, Gain (Loss) [Line Items]    
Change in unrealized gain (loss) on hedged item in fair value hedge 0 0
Change in unrealized gain (loss) on fair value hedging instruments 0 0
Total derivatives designated as accounting hedges | Hedged variable-rate commercial loans | Interest and fees on finance receivables and loans    
Derivative Instruments, Gain (Loss) [Line Items]    
Interest rate cash flow hedge loss reclassified to earnings (5) (7)
Total derivatives designated as accounting hedges | Hedged variable-rate commercial loans | Interest and dividends on investment securities and other earning assets    
Derivative Instruments, Gain (Loss) [Line Items]    
Interest rate cash flow hedge loss reclassified to earnings 0 0
Total derivatives designated as accounting hedges | Hedged variable-rate commercial loans | Interest on long-term debt    
Derivative Instruments, Gain (Loss) [Line Items]    
Interest rate cash flow hedge loss reclassified to earnings $ 0 $ 0