Loans - Impaired Loans, Excluding Acquired Loans (Detail) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Impaired Financing Receivable:
With an Allowance	$ 2,660	$ 1,822
Without an Allowance	507	642
Total Recorded Investment	3,167	2,464
Related Allowance	465	349
Net Recorded Investment	2,702	2,115
Unpaid Principal Balance	3,591	2,894
Average Recorded Investment	2,930	2,138	$ 1,943
Interest Income Recognized	177	163	158
Credit Card Portfolio Segment [Member]
Impaired Financing Receivable:
With an Allowance	715	666
Without an Allowance	0	0
Total Recorded Investment	715	666
Related Allowance	239	209
Net Recorded Investment	476	457
Unpaid Principal Balance	695	647
Average Recorded Investment	673	674	731
Interest Income Recognized	68	67	69
Credit Card Portfolio Segment [Member] \| Geographic Distribution, Domestic [Member]
Impaired Financing Receivable:
With an Allowance	581	541
Without an Allowance	0	0
Total Recorded Investment	581	541
Related Allowance	174	150
Net Recorded Investment	407	391
Unpaid Principal Balance	566	526
Average Recorded Investment	540	539	571
Interest Income Recognized	58	57	58
Credit Card Portfolio Segment [Member] \| Geographic Distribution, Foreign [Member]
Impaired Financing Receivable:
With an Allowance	134	125
Without an Allowance	0	0
Total Recorded Investment	134	125
Related Allowance	65	59
Net Recorded Investment	69	66
Unpaid Principal Balance	129	121
Average Recorded Investment	133	135	160
Interest Income Recognized	10	10	11
Consumer Portfolio Segment [Member]
Impaired Financing Receivable:
With an Allowance	609	553
Without an Allowance	334	361
Total Recorded Investment	943	914
Related Allowance	57	54
Net Recorded Investment	886	860
Unpaid Principal Balance	1,336	1,290
Average Recorded Investment	924	882	844
Interest Income Recognized	93	88	79
Consumer Portfolio Segment [Member] \| Auto
Impaired Financing Receivable:
With an Allowance	316	273
Without an Allowance	207	215
Total Recorded Investment	523	488
Related Allowance	24	22
Net Recorded Investment	499	466
Unpaid Principal Balance	807	772
Average Recorded Investment	501	462	387
Interest Income Recognized	86	82	72
Consumer Portfolio Segment [Member] \| Home loan
Impaired Financing Receivable:
With an Allowance	241	229
Without an Allowance	117	136
Total Recorded Investment	358	365
Related Allowance	19	18
Net Recorded Investment	339	347
Unpaid Principal Balance	464	456
Average Recorded Investment	361	364	388
Interest Income Recognized	5	4	5
Consumer Portfolio Segment [Member] \| Retail banking
Impaired Financing Receivable:
With an Allowance	52	51
Without an Allowance	10	10
Total Recorded Investment	62	61
Related Allowance	14	14
Net Recorded Investment	48	47
Unpaid Principal Balance	65	62
Average Recorded Investment	62	56	69
Interest Income Recognized	2	2	2
Commercial Banking
Impaired Financing Receivable:
With an Allowance	1,336	603
Without an Allowance	173	281
Total Recorded Investment	1,509	884
Related Allowance	169	86
Net Recorded Investment	1,340	798
Unpaid Principal Balance	1,560	957
Average Recorded Investment	1,333	582	368
Interest Income Recognized	16	8	10
Commercial Banking \| Total commercial lending
Impaired Financing Receivable:
With an Allowance	1,332	597
Without an Allowance	173	281
Total Recorded Investment	1,505	878
Related Allowance	169	86
Net Recorded Investment	1,336	792
Unpaid Principal Balance	1,556	950
Average Recorded Investment	1,326	575	360
Interest Income Recognized	16	8	10
Commercial Banking \| Commercial and multifamily real estate
Impaired Financing Receivable:
With an Allowance	83	82
Without an Allowance	29	3
Total Recorded Investment	112	85
Related Allowance	7	11
Net Recorded Investment	105	74
Unpaid Principal Balance	112	88
Average Recorded Investment	111	109	175
Interest Income Recognized	3	3	6
Commercial Banking \| Commercial and industrial
Impaired Financing Receivable:
With an Allowance	1,249	515
Without an Allowance	144	278
Total Recorded Investment	1,393	793
Related Allowance	162	75
Net Recorded Investment	1,231	718
Unpaid Principal Balance	1,444	862
Average Recorded Investment	1,215	466	185
Interest Income Recognized	13	5	4
Commercial Banking \| Small-ticket commercial real estate
Impaired Financing Receivable:
With an Allowance	4	6
Without an Allowance	0	0
Total Recorded Investment	4	6
Related Allowance	0	0
Net Recorded Investment	4	6
Unpaid Principal Balance	4	7
Average Recorded Investment	7	7	8
Interest Income Recognized	$ 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

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
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-URI http://asc.fasb.org/extlink&oid=66008989&loc=d3e5258-111524

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+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 14A
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Amount of allowance for credit losses related to recorded investment.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Recorded Investment
-URI http://asc.fasb.org/extlink&oid=65880944

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-Publisher FASB
-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=66008989&loc=d3e5212-111524

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