Finance Receivables and Loans, Net - Schedule of Accounts, Notes, Loans and Financing Receivables (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total finance receivables and loans	$ 137,501	$ 139,439
Unamortized premiums and discounts and deferred fees and costs	2,300	2,300
Accrued interest receivable	851	853
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total finance receivables and loans	103,095	104,977
Consumer | Automotive
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total finance receivables and loans	83,424	84,320
Consumer | Consumer mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total finance receivables and loans	17,501	18,667
Consumer | Mortgage Finance
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total finance receivables and loans	17,309	18,442
Interest-only mortgage loans	1	2
Consumer | Mortgage — Legacy
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total finance receivables and loans	192	225
Interest-only mortgage loans	12	13
Consumer | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total finance receivables and loans	2,170	1,990
Consumer | Credit Card
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total finance receivables and loans	2,170	1,990
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total finance receivables and loans	34,406	34,462
Commercial | Automotive
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total finance receivables and loans	19,259	18,700
Commercial | Consumer mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total finance receivables and loans	6,323	6,050
Commercial | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total finance receivables and loans	$ 8,824	$ 9,712