Goodwill and Other Intangible Assets - Goodwill Attributable to Each Business Segments (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Goodwill [Roll Forward]
Goodwill, Beginning Balance	$ 13,978us-gaap_Goodwill	$ 13,904us-gaap_Goodwill
Acquisitions	12us-gaap_GoodwillAcquiredDuringPeriod	73us-gaap_GoodwillAcquiredDuringPeriod
Other adjustments	(12)us-gaap_GoodwillOtherChanges	1us-gaap_GoodwillOtherChanges
Goodwill, Ending Balance	13,978us-gaap_Goodwill	13,978us-gaap_Goodwill
Credit Card
Goodwill [Roll Forward]
Goodwill, Beginning Balance	5,005	5,003
Acquisitions	2	0
Other adjustments	(6)	2
Goodwill, Ending Balance	5,001	5,005
Consumer Banking
Goodwill [Roll Forward]
Goodwill, Beginning Balance	4,585	4,583
Acquisitions	10	3
Other adjustments	(2)	(1)
Goodwill, Ending Balance	4,593	4,585
Commercial Banking
Goodwill [Roll Forward]
Goodwill, Beginning Balance	4,388	4,318
Acquisitions	0	70
Other adjustments	(4)	0
Goodwill, Ending Balance	$ 4,384	$ 4,388

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6388280&loc=d3e13770-109266

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- Definition

Amount of increase in asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from a business combination.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

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Amount of other (increase) decrease of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (g)

-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

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