Finance Receivables and Loans, Net (Schedule of Pass And Criticized Credit Quality Indicators of Finance Receivables) (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net	$ 128,609	$ 129,926	$ 126,605
Commercial portfolio segment
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net	38,528	42,686	$ 40,104
Commercial portfolio segment | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net	34,702	38,710
Commercial portfolio segment | Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net	3,826	3,976
Commercial portfolio segment | Automotive loan
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net	29,122	33,672
Commercial portfolio segment | Automotive loan | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net	26,393	30,799
Commercial portfolio segment | Automotive loan | Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net	2,729	2,873
Commercial portfolio segment | Other loan
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net	4,377	4,205
Commercial portfolio segment | Other loan | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net	3,545	3,373
Commercial portfolio segment | Other loan | Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net	832	832
Commercial portfolio segment | Real estate-backed loan
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net	5,029	4,809
Commercial portfolio segment | Real estate-backed loan | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net	4,764	4,538
Commercial portfolio segment | Real estate-backed loan | Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net	$ 265	$ 271