Loans - Impaired Loans, Excluding Acquired Loans (Detail) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Impaired Financing Receivable:
With an Allowance	$ 2,458		$ 2,660
Without an Allowance	509		507
Total Recorded Investment	2,967		3,167
Related Allowance	475		465
Net Recorded Investment	2,492		2,702
Unpaid Principal Balance	3,377		3,591
Average Recorded Investment	3,067	$ 2,698
Interest Income Recognized	39	43
Credit Card Portfolio Segment [Member]
Impaired Financing Receivable:
With an Allowance	735		715
Without an Allowance	0		0
Total Recorded Investment	735		715
Related Allowance	262		239
Net Recorded Investment	473		476
Unpaid Principal Balance	715		695
Average Recorded Investment	726	662
Interest Income Recognized	18	17
Credit Card Portfolio Segment [Member] \| Geographic Distribution, Domestic [Member]
Impaired Financing Receivable:
With an Allowance	588		581
Without an Allowance	0		0
Total Recorded Investment	588		581
Related Allowance	192		174
Net Recorded Investment	396		407
Unpaid Principal Balance	573		566
Average Recorded Investment	585	533
Interest Income Recognized	15	14
Credit Card Portfolio Segment [Member] \| Geographic Distribution, Foreign [Member]
Impaired Financing Receivable:
With an Allowance	147		134
Without an Allowance	0		0
Total Recorded Investment	147		134
Related Allowance	70		65
Net Recorded Investment	77		69
Unpaid Principal Balance	142		129
Average Recorded Investment	141	129
Interest Income Recognized	3	3
Consumer Portfolio Segment [Member]
Impaired Financing Receivable:
With an Allowance	603		609
Without an Allowance	282		334
Total Recorded Investment	885		943
Related Allowance	57		57
Net Recorded Investment	828		886
Unpaid Principal Balance	1,242		1,336
Average Recorded Investment	913	917
Interest Income Recognized	17	23
Consumer Portfolio Segment [Member] \| Auto
Impaired Financing Receivable:
With an Allowance	321		316
Without an Allowance	178		207
Total Recorded Investment	499		523
Related Allowance	29		24
Net Recorded Investment	470		499
Unpaid Principal Balance	768		807
Average Recorded Investment	511	491
Interest Income Recognized	15	22
Consumer Portfolio Segment [Member] \| Home loan
Impaired Financing Receivable:
With an Allowance	237		241
Without an Allowance	94		117
Total Recorded Investment	331		358
Related Allowance	17		19
Net Recorded Investment	314		339
Unpaid Principal Balance	415		464
Average Recorded Investment	344	366
Interest Income Recognized	1	1
Consumer Portfolio Segment [Member] \| Retail banking
Impaired Financing Receivable:
With an Allowance	45		52
Without an Allowance	10		10
Total Recorded Investment	55		62
Related Allowance	11		14
Net Recorded Investment	44		48
Unpaid Principal Balance	59		65
Average Recorded Investment	58	60
Interest Income Recognized	1	0
Commercial Banking
Impaired Financing Receivable:
With an Allowance	1,120		1,336
Without an Allowance	227		173
Total Recorded Investment	1,347		1,509
Related Allowance	156		169
Net Recorded Investment	1,191		1,340
Unpaid Principal Balance	1,420		1,560
Average Recorded Investment	1,428	1,119
Interest Income Recognized	4	3
Commercial Banking \| Total commercial lending
Impaired Financing Receivable:
With an Allowance	1,113		1,332
Without an Allowance	227		173
Total Recorded Investment	1,340		1,505
Related Allowance	156		169
Net Recorded Investment	1,184		1,336
Unpaid Principal Balance	1,412		1,556
Average Recorded Investment	1,422	1,113
Interest Income Recognized	4	3
Commercial Banking \| Commercial and multifamily real estate
Impaired Financing Receivable:
With an Allowance	86		83
Without an Allowance	28		29
Total Recorded Investment	114		112
Related Allowance	5		7
Net Recorded Investment	109		105
Unpaid Principal Balance	114		112
Average Recorded Investment	113	109
Interest Income Recognized	1	1
Commercial Banking \| Commercial and industrial
Impaired Financing Receivable:
With an Allowance	1,027		1,249
Without an Allowance	199		144
Total Recorded Investment	1,226		1,393
Related Allowance	151		162
Net Recorded Investment	1,075		1,231
Unpaid Principal Balance	1,298		1,444
Average Recorded Investment	1,309	1,004
Interest Income Recognized	3	2
Commercial Banking \| Small-ticket commercial real estate
Impaired Financing Receivable:
With an Allowance	7		4
Without an Allowance	0		0
Total Recorded Investment	7		4
Related Allowance	0		0
Net Recorded Investment	7		4
Unpaid Principal Balance	8		$ 4
Average Recorded Investment	6	6
Interest Income Recognized	$ 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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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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+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 14A
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=66008989&loc=SL6953550-111524

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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
-Topic 310
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-Paragraph 15
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-URI http://asc.fasb.org/extlink&oid=66008989&loc=d3e5212-111524

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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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