Finance Receivables and Loans, Net (Schedule of Pass And Criticized Credit Quality Indicators of Finance Receivables) (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	$ 119,002	$ 118,944	$ 110,876
Commercial Portfolio Segment [Member] | Commercial Loan [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	42,402	42,101	$ 37,188
Commercial Portfolio Segment [Member] | Commercial Loan [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	39,508	39,410
Commercial Portfolio Segment [Member] | Commercial Loan [Member] | Criticized [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	2,894	2,691
Commercial Portfolio Segment [Member] | Commercial And Industrial Automobile [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	34,911	35,041
Commercial Portfolio Segment [Member] | Commercial And Industrial Automobile [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	32,878	33,160
Commercial Portfolio Segment [Member] | Commercial And Industrial Automobile [Member] | Criticized [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	2,033	1,881
Commercial Portfolio Segment [Member] | Commercial And Industrial Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	3,499	3,248
Commercial Portfolio Segment [Member] | Commercial And Industrial Other [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	2,814	2,597
Commercial Portfolio Segment [Member] | Commercial And Industrial Other [Member] | Criticized [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	685	651
Commercial Portfolio Segment [Member] | Commercial Real Estate Automobile [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	3,992	3,812
Commercial Portfolio Segment [Member] | Commercial Real Estate Automobile [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	3,816	3,653
Commercial Portfolio Segment [Member] | Commercial Real Estate Automobile [Member] | Criticized [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	$ 176	$ 159