Securitizations and Variable Interest Entities (Schedule of Cash Flow Received from and Paid to Nonconsolidated Securitization Entities) (Details) - Consumer portfolio segment - USD ($) $ in Millions	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017
Automobile loan
Cash Flow Received and Paid to Nonconsolidated Securitization Entities [Line Items]
Cash flows between transferor and transferee, proceeds from transfers completed during the period	$ 24	$ 1,187
Cash flows between transferor and transferee, disbursement for repurchases during the period	(3)	(491)
Cash flows between transferor and transferee, servicing fees	14	25
Cash flows between transferor and transferee, cash flows received on retained interests in securitization entities	13	16
Cash flows between transferor and transferee, representations and warranty recoveries	0
Cash flows between transferor and transferee, other cash flows		4
Residential mortgage
Cash Flow Received and Paid to Nonconsolidated Securitization Entities [Line Items]
Cash flows between transferor and transferee, proceeds from transfers completed during the period	0	0
Cash flows between transferor and transferee, disbursement for repurchases during the period	0	0
Cash flows between transferor and transferee, servicing fees	0	0
Cash flows between transferor and transferee, cash flows received on retained interests in securitization entities	0	0
Cash flows between transferor and transferee, representations and warranty recoveries	$ 2
Cash flows between transferor and transferee, other cash flows		$ 0

Cash Flow Between Transferee and Transferor representations and warranties obligations.

No definition available.

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- Definition

Cash Flow Received and Paid to Nonconsolidated Securitization Entities [Line Items]

+ References

No definition available.

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- Definition

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
-Subparagraph (d)(1)
-URI http://asc.fasb.org/extlink&oid=109247956&loc=d3e107207-111719

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- Definition

Cash Flows between a transferor and a transferee attributable to purchases of previously transferred financial assets (or its underlying collateral) related to 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://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (d)(3)
-URI http://asc.fasb.org/extlink&oid=109247956&loc=d3e107207-111719

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- Definition

Cash flows between transferor and a transferee attributable to the transferor's interests related to a securitization, asset-backed financing arrangement, or similar transfer in which the transferor will have 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://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (d)(5)
-URI http://asc.fasb.org/extlink&oid=109247956&loc=d3e107207-111719

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- Definition

Cash Flows between a transferee and a transferor attributable to servicing fees related to 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://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (d)(4)
-URI http://asc.fasb.org/extlink&oid=109247956&loc=d3e107207-111719

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- Definition

Cash flows between transferee and transferor in payment of the transferor's beneficial interest related to a securitization, asset-backed financing arrangement, or similar transfer in which the transferor has continuing involvement with the transferred financial assets underlying the transaction.

+ References

No definition available.

+ Details

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