Securitizations and Variable Interest Entities (Schedule of Variable Interest Entities) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Variable Interest Entity [Line Items]
Carrying value of assets for VIEs for which we have continuing involvement	$ 37,631	$ 44,940
Carrying value of liabilities for VIEs for which we have continuing involvement	13,490	20,388
Assets of nonconsolidated variable interest entities	2,899	3,034
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	3,574	3,527
Qualitative and Quantitative Information, Transferor's Continuing Involvement, Arrangements of Financial Support, Amount	50	99
Consumer Portfolio Segment [Member] \| Automobile Loan [Member]
Variable Interest Entity [Line Items]
Securitization or Asset-backed Financing Arrangement, Financial Asset for which Transfer is Accounted as Sale, Gain (Loss) on Sale	0	(3)	$ 1
Variable Interest Entity, Consolidated, Carrying Amount, Assets	20,869	27,967
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets	24	0
Variable Interest Entity, Consolidated, Carrying Amount, Liabilities	8,557	12,406
Variable Interest Entity, Nonconsolidated, Carrying Amount, Liabilities	0	0
Assets of nonconsolidated variable interest entities	2,899	3,034
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	2,923	3,034
Continuing Involvement with Continued to be Recognized Transferred Financial Assets, Amount Outstanding	9,600	10,600
Commercial Portfolio Segment [Member] \| Automobile Loan [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets	16,278	16,763
Variable Interest Entity, Consolidated, Carrying Amount, Liabilities	4,764	7,982
Commercial Portfolio Segment [Member] \| Other Financing Receivables [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets	460	210
Variable Interest Entity, Nonconsolidated, Carrying Amount, Liabilities	169	0
Assets of nonconsolidated variable interest entities	0	0
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	$ 651	$ 493

Assets of nonconsolidated variable interest entities

No definition available.

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- Definition

The carrying amount of the assets in the reporting entity's statement of financial position that relate to consolidated and nonconsolidated Variable Interest Entities.

+ References

No definition available.

+ Details

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- Definition

Carrying value of liabilities for VIEs for which we have continuing involvement

+ References

No definition available.

+ Details

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- Definition

The transferor's maximum amount of exposure to loss as a result of its continuing involvement in transferred financial assets.

+ References

No definition available.

+ Details

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- Definition

Reflects, by transferred financial asset type, the amount of sales proceeds in excess of or deficient from the sum of the carrying amounts of transferred financial assets plus transaction costs, including those transactions in which the seller/transferor has continuing involvement with the financial assets that have been transferred.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=64830801&loc=d3e107207-111719

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 10
-Section 40
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=65892426&loc=d3e96813-111708

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- Definition

Amount of transferred financial assets in which the transferor has continuing involvement with the assets underlying the transaction that continue to be recognized in the statement of financial position. Includes, but is not limited to, servicing, recourse, and restrictions on transferor's interests in transferred financial assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=64830801&loc=d3e107314-111719

+ Details

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- Definition

The carrying amount of the consolidated Variable Interest Entity's assets included in the reporting entity's statement of financial position.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (bb)
-URI http://asc.fasb.org/extlink&oid=64801991&loc=d3e5710-111685

+ Details

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- Definition

The carrying amount of the consolidated Variable Interest Entity's liabilities included in the reporting entity's statement of financial position.

+ References

+ Details

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- Definition

The reporting entity's maximum amount of exposure to loss as a result of its involvement with the Variable Interest Entity (VIE).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph b
-URI http://asc.fasb.org/extlink&oid=64801991&loc=d3e5728-111685

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=64801991&loc=d3e5747-111685

+ Details

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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- Definition

Carrying amount of the assets in the reporting entity's statement of financial position that relate to the reporting entity's variable interest in the Variable Interest Entity (VIE), where the reporting entity is not the VIE's primary beneficiary.

+ References

+ Details

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- Definition

Carrying amount of the liabilities in the reporting entity's statement of financial position that relate to the reporting entity's variable interest in the Variable Interest Entity (VIE), where the reporting entity is not the VIE's primary beneficiary.

+ References

+ Details

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