Finance Receivables and Loans, Net (Troubled Debt Restructurings) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Financing Receivable, Modifications [Line Items]
Loans and Leases Receivable, Impaired, Commitment to Lend	$ 0		$ 4
Financing Receivable, Modifications, Recorded Investment	557		681
Financing Receivable, Modifications, Number of Contracts	4,095	5,583
Financing Receivable, Modifications, Pre-Modification Recorded Investment	70	204
Financing Receivable, Modifications, Post-Modification Recorded Investment	59	187
Consumer Loans Auto Financing Receivable [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	4,055	5,359
Financing Receivable, Modifications, Pre-Modification Recorded Investment	63	84
Financing Receivable, Modifications, Post-Modification Recorded Investment	53	71
Residential Mortgage [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	40	218
Financing Receivable, Modifications, Pre-Modification Recorded Investment	7	49
Financing Receivable, Modifications, Post-Modification Recorded Investment	6	45
Commercial Loan [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	0	6
Financing Receivable, Modifications, Pre-Modification Recorded Investment	0	71
Financing Receivable, Modifications, Post-Modification Recorded Investment	0	71
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 And Industrial Other [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	0	3
Financing Receivable, Modifications, Pre-Modification Recorded Investment	0	48
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 0	$ 48

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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=35738203&loc=SL6953676-111524

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Post-modification amount of investment in financing receivables modified by troubled debt restructurings.

+ References

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- Definition

Pre-modification amount of investment in financing receivables modified by troubled debt restructurings.

+ References

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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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- Definition

Reflects the unfunded portion of contractual agreements to lend funds to borrowers for loans whose terms have been modified by troubled debt restructuring.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 40

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=25495931&loc=d3e18794-111554

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