Finance Receivables and Loans, Net (Schedule of Pass And Criticized Credit Quality Indicators of Finance Receivables) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019	Sep. 30, 2019
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net	$ 118,028	$ 128,231	$ 128,609
Commercial portfolio segment
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net	27,868	38,307	$ 38,528
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	17,886	28,332
Commercial portfolio segment | Automotive loan | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net	15,475	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	5,131	5,014
Commercial portfolio segment | Other loan | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net	3,602	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	4,851	4,961
Commercial portfolio segment | Real estate-backed loan | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net	$ 4,334	4,620
Commercial portfolio segment | Real estate-backed loan | Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net		$ 341