Finance Receivables and Loans, Net (Schedule of Pass And Criticized Credit Quality Indicators of Finance Receivables) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment [Line Items]
Finance receivables and loans, net	$ 129,926	$ 122,893
Commercial portfolio segment | Commercial loan
Financing Receivable, Recorded Investment [Line Items]
Finance receivables and loans, net	42,686	41,072
Commercial portfolio segment | Commercial loan | Pass
Financing Receivable, Recorded Investment [Line Items]
Finance receivables and loans, net	38,710	37,991
Commercial portfolio segment | Commercial loan | Criticized
Financing Receivable, Recorded Investment [Line Items]
Finance receivables and loans, net	3,976	3,081
Commercial portfolio segment | Commercial and industrial automotive
Financing Receivable, Recorded Investment [Line Items]
Finance receivables and loans, net	33,672	33,025
Commercial portfolio segment | Commercial and industrial automotive | Pass
Financing Receivable, Recorded Investment [Line Items]
Finance receivables and loans, net	30,799	30,982
Commercial portfolio segment | Commercial and industrial automotive | Criticized
Financing Receivable, Recorded Investment [Line Items]
Finance receivables and loans, net	2,873	2,043
Commercial portfolio segment | Commercial and industrial other
Financing Receivable, Recorded Investment [Line Items]
Finance receivables and loans, net	4,205	3,887
Commercial portfolio segment | Commercial and industrial other | Pass
Financing Receivable, Recorded Investment [Line Items]
Finance receivables and loans, net	3,373	2,986
Commercial portfolio segment | Commercial and industrial other | Criticized
Financing Receivable, Recorded Investment [Line Items]
Finance receivables and loans, net	832	901
Commercial portfolio segment | Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Finance receivables and loans, net	4,809	4,160
Commercial portfolio segment | Commercial real estate | Pass
Financing Receivable, Recorded Investment [Line Items]
Finance receivables and loans, net	4,538	4,023
Commercial portfolio segment | Commercial real estate | Criticized
Financing Receivable, Recorded Investment [Line Items]
Finance receivables and loans, net	$ 271	$ 137