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	9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024
Automotive
Cash Flow Received and Paid to Nonconsolidated Securitization Entities [Line Items]
Cash proceeds from transfers completed during the period	$ 1,010	$ 1,468
Servicing fees	44	44
Cash flows received on retained interests in securitization entities	33	41
Other cash flows received	3	2
Cash disbursements for repurchases during the period	1	1
Other
Cash Flow Received and Paid to Nonconsolidated Securitization Entities [Line Items]
Cash proceeds from transfers completed during the period	8	35
Servicing fees	$ 1	$ 5