Parent Company Condensed Financial Information - Schedule of Condensed Balance Sheet (Details) - USD ($) $ in Millions	Dec. 31, 2024	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Cash and cash equivalents	$ 10,292				$ 6,945
Equity securities	871				810
Finance receivables and loans, net of unearned income	136,030				139,439
Allowance for loan losses	(3,714)				(3,587)				$ (3,711)
Finance receivables and loans, net	132,316				135,852
Other assets	10,660	$ 9,947	$ 9,949	$ 9,420	9,418	$ 9,612	$ 9,155	$ 9,142
Total assets	191,836				196,329				191,826
Long-term debt	17,495				17,570
Interest payable	890				858
Accounts payable	505				509
Accrued expenses and other liabilities	2,814				2,726
Total liabilities	177,933				182,626
Total equity	13,903				13,703				$ 12,859	$ 17,050
Total liabilities and equity	191,836				196,329
Parent company
Cash and cash equivalents	4,579				3,911
Equity securities	1				16
Finance receivables and loans, net of unearned income	810				1,478
Allowance for loan losses	10				22
Finance receivables and loans, net	820				1,500
Bank subsidiaries	13,777				13,629
Nonbank subsidiaries	5,335				4,503
Investment in operating leases, net	10				16
Other assets	1,774				1,536
Total assets	26,547				25,374
Long-term debt	11,068				10,427
Interest payable	134				98
Accrued expenses and other liabilities	357				333
Total liabilities	12,644				11,671
Total equity	13,903				13,703
Total liabilities and equity	26,547				25,374
Deposits by parent at subsidiaries	4,500				3,900
Parent company | Senior Notes
Long-term debt	2,000				2,000
Parent company | Related Party
Intercompany receivables from subsidiaries	251				263
Intercompany debt to subsidiaries	1,046				772
Accounts payable	$ 39				$ 41