Securitizations and Variable Interest Entities (Schedule of Variable Interest Entities) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Variable Interest Entity [Line Items]
Securitization or asset-backed financing arrangement, financial asset for which transfer is accounted as sale, gain on sale	$ 1	$ 2	$ 0
Variable interest entity, assets deconsolidated	(1,235)	(1,964)
Variable interest entity, carrying value of assets for which we have continuing involvement	28,195	30,776
Variable interest entity, carrying value of liabilities for which we have continuing involvement	10,845	10,483
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	2,334	2,791
Commercial portfolio segment
Variable Interest Entity [Line Items]
Variable interest entity, nonconsolidated, carrying amount, assets	806	592
Variable Interest Entity, nonconsolidated, carrying amount, liabilities	326	248
Variable interest entity, assets deconsolidated	0	0
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	1,054	790
Automobile loan \| Consumer portfolio segment
Variable Interest Entity [Line Items]
Variable interest entity, consolidated, carrying amount, assets	16,255	17,597
Variable interest entity, consolidated, carrying amount, liabilities	6,573	7,677
Variable interest entity, nonconsolidated, carrying amount, assets	45	37
Variable Interest Entity, nonconsolidated, carrying amount, liabilities	0	0
Variable interest entity, assets deconsolidated	(1,235)	(1,964)
Cash flows between transferor and transferee, proceeds from transfers completed during the period	24	1,187	$ 1,715
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	1,280	2,001
Automobile loan \| Consumer portfolio segment \| Held-to-maturity securities
Variable Interest Entity [Line Items]
Variable interest entity, consolidated, carrying amount, assets	43	36
Automobile loan \| Consumer portfolio segment \| Other assets
Variable Interest Entity [Line Items]
Variable interest entity, consolidated, carrying amount, assets	2	1
Automobile loan \| Commercial portfolio segment
Variable Interest Entity [Line Items]
Variable interest entity, consolidated, carrying amount, assets	11,089	12,550
Variable interest entity, consolidated, carrying amount, liabilities	3,946	2,558
Unencumbered \| Automobile loan \| Consumer portfolio segment
Variable Interest Entity [Line Items]
Variable interest entity, consolidated, carrying amount, assets	8,400	8,500
Variable interest entity, consolidated, carrying amount, liabilities	25	$ 29
Amount deconsolidated during the period \| Automobile loan \| Consumer portfolio segment
Variable Interest Entity [Line Items]
Variable interest entity, assets deconsolidated	(545)
Variable interest entity, liabilities deconsolidated	$ (497)

Assets of nonconsolidated variable interest entities

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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.

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

+ References

No definition available.

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Liabilities of Nonconsolidated Variable Interest Entities

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Cash Flows between a transferor and a transferee attributable to newly transferred assets related to either a securitization, asset-backed financing arrangement, or similar transfer in which the transferor has continuing involvement with the transferred financial assets underlying the transaction (including, but not limited to, servicing, recourse, and restrictions on transferor's interests in the transferred financial assets).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 20
-Section 50
-Paragraph 3
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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

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-Publisher FASB
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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.

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

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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).

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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

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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

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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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.

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