Finance Receivables and Loans, Net (Past Due Financing Receivables and Loans Commercial) (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Financing Receivable, Past Due [Line Items]
Finance receivables and loans, net	$ 113,076	$ 118,534
Commercial portfolio segment
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	10	2
Financing receivable, recorded investment, current	25,675	29,330
Finance receivables and loans, net	25,685	29,332
Automotive loan | Commercial portfolio segment
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	0	0
Financing receivable, recorded investment, current	15,132	19,082
Finance receivables and loans, net	15,132	19,082
Other loan | Commercial portfolio segment
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	5	0
Financing receivable, recorded investment, current	5,536	5,242
Finance receivables and loans, net	5,541	5,242
Real estate-backed loan | Commercial portfolio segment
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	5	2
Financing receivable, recorded investment, current	5,007	5,006
Finance receivables and loans, net	5,012	5,008
Financing receivables, 30 to 59 days past due | Commercial portfolio segment
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	3	0
Financing receivables, 30 to 59 days past due | Automotive loan | Commercial portfolio segment
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	0	0
Financing receivables, 30 to 59 days past due | Other loan | Commercial portfolio segment
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	0	0
Financing receivables, 30 to 59 days past due | Real estate-backed loan | Commercial portfolio segment
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	3	0
Financing receivables, 60 to 89 days past due | Commercial portfolio segment
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	0	0
Financing receivables, 60 to 89 days past due | Automotive loan | Commercial portfolio segment
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	0	0
Financing receivables, 60 to 89 days past due | Other loan | Commercial portfolio segment
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	0	0
Financing receivables, 60 to 89 days past due | Real estate-backed loan | Commercial portfolio segment
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	0	0
Financing receivables, equal to greater than 90 days past due | Commercial portfolio segment
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	7	2
Financing receivables, equal to greater than 90 days past due | Automotive loan | Commercial portfolio segment
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	0	0
Financing receivables, equal to greater than 90 days past due | Other loan | Commercial portfolio segment
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	5	0
Financing receivables, equal to greater than 90 days past due | Real estate-backed loan | Commercial portfolio segment
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	$ 2	$ 2