Finance Receivables and Loans, Net (Past Due Financing Receivables and Loans Commercial) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Financing Receivable, Past Due [Line Items]
Finance receivables and loans, net	$ 118,534	$ 128,231
Commercial portfolio segment
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	2	83
Financing receivable, recorded investment, current	29,330	38,224
Finance receivables and loans, net	29,332	38,307
Automotive loan | Commercial portfolio segment
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	0	62
Financing receivable, recorded investment, current	19,082	28,270
Finance receivables and loans, net	19,082	28,332
Other loan | Commercial portfolio segment
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	0	17
Financing receivable, recorded investment, current	5,242	4,997
Finance receivables and loans, net	5,242	5,014
Real estate-backed loan | Commercial portfolio segment
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	2	4
Financing receivable, recorded investment, current	5,006	4,957
Finance receivables and loans, net	5,008	4,961
Financing receivables, 30 to 59 days past due | Commercial portfolio segment
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	0	34
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	34
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	0	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	2	49
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	28
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	0	17
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	$ 4