Derivative Instruments and Hedging Activities - Schedule of Fair Value Hedging Instruments, Statements of Financial Performance and Financial Position, Location (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Hedged liability, fair value hedge	$ 5,987	$ 7,750
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	$ 15,194	$ 16,302
Hedged asset, fair value hedge, cumulative increase (decrease)	$ (248)	$ (79)
Hedged Asset, Statement of Financial Position [Extensible Enumeration]	Available-for-sale securities (amortized cost of $26,810 and $28,416)	Available-for-sale securities (amortized cost of $26,810 and $28,416)
Closed portfolio and beneficial interest, last-of-layer, amortized cost	$ 13,900	$ 14,800
Amortized cost	13,600	14,600
Basis adjustment for active hedge	(209)	(45)
Hedged asset, last-of-layer, amount	12,000	11,300
Available-for-sale securities | Total derivatives designated as accounting hedges
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Basis adjustment for active hedge	(106)	75
Finance receivables and loans, net
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Hedged asset, fair value hedge	34,493	54,189
Hedged asset, fair value hedge, cumulative increase (decrease)	$ (51)	$ (93)
Hedged Asset, Statement of Financial Position [Extensible Enumeration]	Finance receivables and loans, net	Finance receivables and loans, net
Basis adjustment for active hedge	$ (51)	$ (93)
Hedged asset, last-of-layer, amount	20,100	23,200
Closed portfolio, carrying value	33,400	50,000
Finance receivables and loans, net | Total derivatives designated as accounting hedges
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Basis adjustment for active hedge	(41)	(66)
Long-term debt
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Hedged liability, fair value hedge, cumulative increase (decrease)	88	100
Discontinued hedge | Available-for-sale securities
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Hedged asset, discontinued fair value hedge, cumulative increase (decrease)	(132)	(156)
Basis adjustment for active hedge	(103)	(120)
Discontinued hedge | Finance receivables and loans, net
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Hedged asset, discontinued fair value hedge, cumulative increase (decrease)	(10)	(27)
Basis adjustment for active hedge	(10)	(27)
Discontinued hedge | Long-term debt
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Hedged liability, discontinued fair value hedge, cumulative increase (decrease)	$ 88	$ 100