Finance Receivables and Loans, Net (Schedule of Pass And Criticized Credit Quality Indicators of Finance Receivables) (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net	$ 128,139	$ 128,231	$ 130,055
Commercial portfolio segment
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net	38,073	38,307	$ 40,844
Commercial portfolio segment | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net		34,080
Commercial portfolio segment | Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net		4,227
Commercial portfolio segment | Automotive loan
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net	27,394	28,332
Commercial portfolio segment | Automotive loan | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net	23,705	25,235
Commercial portfolio segment | Automotive loan | Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net		3,097
Commercial portfolio segment | Other loan
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net	5,878	5,014
Commercial portfolio segment | Other loan | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net	4,727	4,225
Commercial portfolio segment | Other loan | Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net		789
Commercial portfolio segment | Real estate-backed loan
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net	4,801	4,961
Commercial portfolio segment | Real estate-backed loan | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net	$ 4,482	4,620
Commercial portfolio segment | Real estate-backed loan | Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net		$ 341