Loans - Impaired Loans, Excluding Acquired Loans (Detail) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Impaired Financing Receivable:
With an Allowance	$ 2,382		$ 2,382		$ 2,660
Without an Allowance	518		518		507
Total Recorded Investment	2,900		2,900		3,167
Related Allowance	462		462		465
Net Recorded Investment	2,438		2,438		2,702
Unpaid Principal Balance	3,699		3,699		3,591
Average Recorded Investment	2,935	$ 2,987	3,011	$ 2,813
Interest Income Recognized	36	43	75	86
Credit Card Portfolio Segment [Member]
Impaired Financing Receivable:
With an Allowance	745		745		715
Without an Allowance	0		0		0
Total Recorded Investment	745		745		715
Related Allowance	265		265		239
Net Recorded Investment	480		480		476
Unpaid Principal Balance	726		726		695
Average Recorded Investment	740	656	732	660
Interest Income Recognized	18	16	36	33
Credit Card Portfolio Segment [Member] \| Geographic Distribution, Domestic [Member]
Impaired Financing Receivable:
With an Allowance	589		589		581
Without an Allowance	0		0		0
Total Recorded Investment	589		589		581
Related Allowance	189		189		174
Net Recorded Investment	400		400		407
Unpaid Principal Balance	575		575		566
Average Recorded Investment	588	521	586	528
Interest Income Recognized	16	14	31	28
Credit Card Portfolio Segment [Member] \| Geographic Distribution, Foreign [Member]
Impaired Financing Receivable:
With an Allowance	156		156		134
Without an Allowance	0		0		0
Total Recorded Investment	156		156		134
Related Allowance	76		76		65
Net Recorded Investment	80		80		69
Unpaid Principal Balance	151		151		129
Average Recorded Investment	152	135	146	132
Interest Income Recognized	2	2	5	5
Consumer Portfolio Segment [Member]
Impaired Financing Receivable:
With an Allowance	594		594		609
Without an Allowance	296		296		334
Total Recorded Investment	890		890		943
Related Allowance	56		56		57
Net Recorded Investment	834		834		886
Unpaid Principal Balance	1,272		1,272		1,336
Average Recorded Investment	889	918	905	917
Interest Income Recognized	12	23	29	46
Consumer Portfolio Segment [Member] \| Auto
Impaired Financing Receivable:
With an Allowance	311		311		316
Without an Allowance	172		172		207
Total Recorded Investment	483		483		523
Related Allowance	28		28		24
Net Recorded Investment	455		455		499
Unpaid Principal Balance	766		766		807
Average Recorded Investment	491	494	501	492
Interest Income Recognized	11	21	26	43
Consumer Portfolio Segment [Member] \| Home loan
Impaired Financing Receivable:
With an Allowance	235		235		241
Without an Allowance	114		114		117
Total Recorded Investment	349		349		358
Related Allowance	18		18		19
Net Recorded Investment	331		331		339
Unpaid Principal Balance	444		444		464
Average Recorded Investment	342	364	346	364
Interest Income Recognized	1	1	2	2
Consumer Portfolio Segment [Member] \| Retail banking
Impaired Financing Receivable:
With an Allowance	48		48		52
Without an Allowance	10		10		10
Total Recorded Investment	58		58		62
Related Allowance	10		10		14
Net Recorded Investment	48		48		48
Unpaid Principal Balance	62		62		65
Average Recorded Investment	56	60	58	61
Interest Income Recognized	0	1	1	1
Commercial Banking
Impaired Financing Receivable:
With an Allowance	1,043		1,043		1,336
Without an Allowance	222		222		173
Total Recorded Investment	1,265		1,265		1,509
Related Allowance	141		141		169
Net Recorded Investment	1,124		1,124		1,340
Unpaid Principal Balance	1,701		1,701		1,560
Average Recorded Investment	1,306	1,413	1,374	1,236
Interest Income Recognized	6	4	10	7
Commercial Banking \| Total commercial lending
Impaired Financing Receivable:
With an Allowance	1,035		1,035		1,332
Without an Allowance	222		222		173
Total Recorded Investment	1,257		1,257		1,505
Related Allowance	141		141		169
Net Recorded Investment	1,116		1,116		1,336
Unpaid Principal Balance	1,691		1,691		1,556
Average Recorded Investment	1,298	1,405	1,367	1,229
Interest Income Recognized	6	4	10	7
Commercial Banking \| Commercial and multifamily real estate
Impaired Financing Receivable:
With an Allowance	107		107		83
Without an Allowance	30		30		29
Total Recorded Investment	137		137		112
Related Allowance	8		8		7
Net Recorded Investment	129		129		105
Unpaid Principal Balance	140		140		112
Average Recorded Investment	125	128	121	113
Interest Income Recognized	1	1	2	2
Commercial Banking \| Commercial and industrial
Impaired Financing Receivable:
With an Allowance	928		928		1,249
Without an Allowance	192		192		144
Total Recorded Investment	1,120		1,120		1,393
Related Allowance	133		133		162
Net Recorded Investment	987		987		1,231
Unpaid Principal Balance	1,551		1,551		1,444
Average Recorded Investment	1,173	1,277	1,246	1,116
Interest Income Recognized	5	3	8	5
Commercial Banking \| Small-ticket commercial real estate
Impaired Financing Receivable:
With an Allowance	8		8		4
Without an Allowance	0		0		0
Total Recorded Investment	8		8		4
Related Allowance	0		0		0
Net Recorded Investment	8		8		4
Unpaid Principal Balance	10		10		$ 4
Average Recorded Investment	8	8	7	7
Interest Income Recognized	$ 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=66008989&loc=d3e5212-111524

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-Publisher FASB
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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.

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-Publisher FASB
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-Topic 310
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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Recorded Investment
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Amount of unpaid principal balance of impaired financing receivables with related allowance for credit losses and without related allowance for credit losses.

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