Derivative Instruments and Hedging Activities - Schedule of Fair Value Hedging Instruments, Statements of Financial Performance and Financial Position, Location (Details) - USD ($) $ in Millions	Jun. 30, 2025	Dec. 31, 2024
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Hedged liability, fair value hedge	$ 4,394	$ 5,987
Hedged Liability, Statement of Financial Position [Extensible Enumeration]	Long-term debt	Long-term debt
Available-for-sale securities
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Hedged asset, fair value hedge	$ 15,641	$ 15,194
Hedged asset, fair value hedge, cumulative increase (decrease)	$ 5	$ (248)
Hedged Asset, Statement of Financial Position [Extensible Enumeration]	Available-for-sale securities (amortized cost of $25,715 and $26,810)	Available-for-sale securities (amortized cost of $25,715 and $26,810)
Closed portfolio and beneficial interest, last-of-layer, amortized cost	$ 14,100	$ 13,900
Amortized cost	13,800	13,600
Cumulative basis adjustment for active hedges, asset (liability)	(12)	(209)
Hedged asset, last-of-layer, amount	11,500	12,000
Available-for-sale securities | Total derivatives designated as accounting hedges
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Cumulative basis adjustment for active hedges, asset (liability)	83	(106)
Finance receivables and loans, net
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Hedged asset, fair value hedge	36,673	34,493
Hedged asset, fair value hedge, cumulative increase (decrease)	$ (6)	$ (51)
Hedged Asset, Statement of Financial Position [Extensible Enumeration]	Finance receivables and loans, net	Finance receivables and loans, net
Cumulative basis adjustment for active hedges, asset (liability)	$ (6)	$ (51)
Hedged asset, last-of-layer, amount	16,000	20,100
Closed portfolio, carrying value	28,100	33,400
Finance receivables and loans, net | Total derivatives designated as accounting hedges
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Cumulative basis adjustment for active hedges, asset (liability)	(8)	(41)
Long-term debt
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Hedged liability, fair value hedge, cumulative increase (decrease)	84	88
Discontinued hedge | Available-for-sale securities
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Hedged asset, discontinued fair value hedge, cumulative increase (decrease)	(96)	(132)
Cumulative basis adjustment for active hedges, asset (liability)	(95)	(103)
Discontinued hedge | Finance receivables and loans, net
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Hedged asset, discontinued fair value hedge, cumulative increase (decrease)	2	(10)
Cumulative basis adjustment for active hedges, asset (liability)	2	(10)
Discontinued hedge | Long-term debt
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Hedged liability, discontinued fair value hedge, cumulative increase (decrease)	$ 84	$ 88