Securitizations and Variable Interest Entities - Schedule of Cash Flows with Nonconsolidated Special-Purpose Entities (Details) - Off-balance sheet variable interest entities - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Cash Flow Received and Paid to Nonconsolidated Securitization Entities [Line Items]
Total	$ 1,596	$ 826
Automotive | Consumer
Cash Flow Received and Paid to Nonconsolidated Securitization Entities [Line Items]
Cash proceeds from transfers completed during the period	1,468	707
Servicing fees	44	11
Cash flows received on retained interests in securitization entities	41	0
Cash disbursements for repurchases during the period	1	0
Other cash flows	2	1
Consumer other | Consumer
Cash Flow Received and Paid to Nonconsolidated Securitization Entities [Line Items]
Cash proceeds from transfers completed during the period	35	100
Servicing fees	$ 5	$ 7