Equity in Net Assets of Nonconsolidated Affiliates - Aggregated Financial Data (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Schedule of Equity Method Investments [Line Items]
Total assets	$ 141,030	$ 132,011
Total liabilities	125,838	116,468
Finance charge income	7,669	6,204	$ 4,521
Provision for loan losses	1,029	826	654
Income before income taxes	2,645	2,985	4,076
Net income	1,860	2,245	3,084
Non-consolidated affiliates
Schedule of Equity Method Investments [Line Items]
Finance charge income	928	1,373	1,636
Provision for loan losses	226	182	172
Income before income taxes	246	525	661
Net income	$ 185	$ 393	$ 494
SAIC-GMAC Automotive Finance Company Limited (SAIC-GMAC)
Schedule of Equity Method Investments [Line Items]
Ownership percentage (as a percent)	35.00%	35.00%
SAIC-GMF Leasing Co. Ltd.
Schedule of Equity Method Investments [Line Items]
Ownership percentage (as a percent)	35.00%	35.00%
Equity Method Investment, Nonconsolidated Investee or Group of Investees
Schedule of Equity Method Investments [Line Items]
Finance receivables, net	$ 8,852	$ 18,142
Total assets	9,966	19,629
Debt	5,421	13,692
Total liabilities	$ 6,495	$ 15,751