Finance Receivables and Loans, Net (Schedule of Pass And Criticized Credit Quality Indicators of Finance Receivables) (Details) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	$ 120,528	$ 118,944	$ 112,653
Commercial Portfolio Segment [Member] | Commercial Loan [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	42,460	42,101	$ 38,288
Commercial Portfolio Segment [Member] | Commercial Loan [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	39,616	39,410
Commercial Portfolio Segment [Member] | Commercial Loan [Member] | Criticized [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	2,844	2,691
Commercial Portfolio Segment [Member] | Commercial And Industrial Automobile [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	34,782	35,041
Commercial Portfolio Segment [Member] | Commercial And Industrial Automobile [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	32,851	33,160
Commercial Portfolio Segment [Member] | Commercial And Industrial Automobile [Member] | Criticized [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	1,931	1,881
Commercial Portfolio Segment [Member] | Commercial And Industrial Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	3,620	3,248
Commercial Portfolio Segment [Member] | Commercial And Industrial Other [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	2,859	2,597
Commercial Portfolio Segment [Member] | Commercial And Industrial Other [Member] | Criticized [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	761	651
Commercial Portfolio Segment [Member] | Commercial Real Estate Automobile [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	4,058	3,812
Commercial Portfolio Segment [Member] | Commercial Real Estate Automobile [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	3,906	3,653
Commercial Portfolio Segment [Member] | Commercial Real Estate Automobile [Member] | Criticized [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	$ 152	$ 159