Securitizations and Variable Interest Entities - Schedule of Quantitative Information and Net Credit Losses about Securitized and Other Financial Assets Managed Together (Details) - Off-balance sheet variable interest entities - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Derecognized Assets, Securitized or Asset-backed Financing Arrangement Assets and any Other Financial Assets Managed Together [Line Items]
Total amount	$ 3,149		$ 3,149		$ 2,639
Amount 60 days or more past due	109		109		72
Net credit losses	35	$ 18	97	$ 35
Off-balance-sheet securitization entities | Automotive | Consumer
Derecognized Assets, Securitized or Asset-backed Financing Arrangement Assets and any Other Financial Assets Managed Together [Line Items]
Total amount	1,948		1,948		1,558
Amount 60 days or more past due	19		19		11
Net credit losses	6	0	14	0
Whole-loan sales | Automotive | Consumer
Derecognized Assets, Securitized or Asset-backed Financing Arrangement Assets and any Other Financial Assets Managed Together [Line Items]
Total amount	1,108		1,108		956
Amount 60 days or more past due	79		79		44
Net credit losses	22	10	54	14
Whole-loan sales | Consumer other | Consumer
Derecognized Assets, Securitized or Asset-backed Financing Arrangement Assets and any Other Financial Assets Managed Together [Line Items]
Total amount	93		93		125
Amount 60 days or more past due	11		11		$ 17
Net credit losses	$ 7	$ 8	$ 29	$ 21