Finance Receivables and Loans, Net (Schedule of Average Balance and Interest Income of Impaired Finance Receivables) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Average Recorded Investment	$ 775	$ 717	$ 746	$ 697
Impaired Financing Receivable, Interest Income, Accrual Method	8	7	32	21
Consumer Portfolio Segment [Member] \| Consumer Loan [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Average Recorded Investment	628	600	612	598
Impaired Financing Receivable, Interest Income, Accrual Method	7	6	22	19
Consumer Portfolio Segment [Member] \| Automobile Loan [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Average Recorded Investment	389	347	368	340
Impaired Financing Receivable, Interest Income, Accrual Method	5	4	15	12
Consumer Portfolio Segment [Member] \| Residential Mortgage [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Average Recorded Investment	239	253	244	258
Impaired Financing Receivable, Interest Income, Accrual Method	2	2	7	7
Consumer Portfolio Segment [Member] \| Mortgage Finance [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Average Recorded Investment	8	8	8	8
Impaired Financing Receivable, Interest Income, Accrual Method	0	0	0	0
Consumer Portfolio Segment [Member] \| Mortgage - Legacy [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Average Recorded Investment	231	245	236	250
Impaired Financing Receivable, Interest Income, Accrual Method	2	2	7	7
Commercial Portfolio Segment [Member] \| Commercial Loan [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Average Recorded Investment	147	117	134	99
Impaired Financing Receivable, Interest Income, Accrual Method	1	1	10	2
Commercial Portfolio Segment [Member] \| Commercial And Industrial Automobile [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Average Recorded Investment	77	48	55	35
Impaired Financing Receivable, Interest Income, Accrual Method	1	1	2	1
Commercial Portfolio Segment [Member] \| Commercial And Industrial Other [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Average Recorded Investment	63	63	73	58
Impaired Financing Receivable, Interest Income, Accrual Method	0	0	8	1
Commercial Portfolio Segment [Member] \| Commercial Real Estate Automobile [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Average Recorded Investment	7	6	6	6
Impaired Financing Receivable, Interest Income, Accrual Method	$ 0	$ 0	$ 0	$ 0

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Average amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5212-111524

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5258-111524

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Amount of interest income recognized that the financing receivables (with related allowance for credit losses and without a related allowance for credit losses) were impaired.

+ References

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