Securitizations and Variable Interest Entities - Schedule of Cash Flows with Nonconsolidated Special-Purpose Entities (Details) - Off-balance sheet variable interest entities - Consumer - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024
Automotive
Cash Flow Received and Paid to Nonconsolidated Securitization Entities [Line Items]
Cash proceeds from transfers completed during the period	$ 582	$ 1,387
Servicing fees	28	29
Cash flows received on retained interests in securitization entities	23	27
Other cash flows	2	1
Cash disbursements for repurchases during the period	1	0
Other
Cash Flow Received and Paid to Nonconsolidated Securitization Entities [Line Items]
Cash proceeds from transfers completed during the period	8	25
Servicing fees	$ 1	$ 3