Finance Receivables And Loans, Net Finance Receivables and Loans, Net (Troubled Debt Restructurings) (Details) $ in Millions	12 Months Ended
Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	17,428	17,913
Financing Receivable, Modifications, Pre-Modification Recorded Investment	$ 348	$ 362
Financing Receivable, Modifications, Post-Modification Recorded Investment	305	$ 332
Financing Receivable, Modifications, Recorded Investment	625
Total TDR movement during the period	$ (56)
Consumer Portfolio Segment [Member] \| Automobile Loan [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	17,222	17,511
Financing Receivable, Modifications, Pre-Modification Recorded Investment	$ 278	$ 211
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 237	$ 187
Consumer Portfolio Segment [Member] \| Residential Mortgage [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	204	396
Financing Receivable, Modifications, Pre-Modification Recorded Investment	$ 46	$ 80
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 44	$ 74
Commercial Portfolio Segment [Member] \| Commercial Loan [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	2	6
Financing Receivable, Modifications, Pre-Modification Recorded Investment	$ 24	$ 71
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 24	$ 71
Commercial Portfolio Segment [Member] \| Commercial And Industrial Automobile [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	0	3
Financing Receivable, Modifications, Pre-Modification Recorded Investment	$ 0	$ 23
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 0	$ 23
Commercial Portfolio Segment [Member] \| Commercial And Industrial Other [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	1	3
Financing Receivable, Modifications, Pre-Modification Recorded Investment	$ 21	$ 48
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 21	$ 48
Commercial Portfolio Segment [Member] \| Commercial Real Estate Automobile [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	1	0
Financing Receivable, Modifications, Pre-Modification Recorded Investment	$ 3	$ 0
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 3	$ 0

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Number of financing receivables that have been modified by troubled debt restructurings.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=49124121&loc=SL6953676-111524

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- Definition

The amount of the outstanding recorded investment related to financing receivables that have been modified by troubled debt restructurings.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 40
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=25495931&loc=d3e18845-111554

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