Goodwill and Other Intangible Assets - Changes in the Carrying Amount of Goodwill by Reportable Segment (Detail) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2014	Dec. 31, 2015	Dec. 31, 2013
Goodwill [Line Items]
Goodwill	$ 6,337	$ 6,337	$ 6,369
Goodwill, Transfers	8
Goodwill, Written off Related to Sale of Business Unit	(40)
Consumer Banking and Private Wealth Management [Member]
Goodwill [Line Items]
Goodwill	4,262		4,262
Goodwill, Transfers	0
Goodwill, Written off Related to Sale of Business Unit	0
Wholesale Banking [Member]
Goodwill [Line Items]
Goodwill	2,075		$ 2,107
Goodwill, Transfers	8
Goodwill, Written off Related to Sale of Business Unit	$ (40)

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

+ Details

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Balance Type:	debit
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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- Definition

Amount of transfers 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 among segments.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of divestiture of an asset representing 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 (d)
-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

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- Details

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Namespace Prefix:
Data Type:	na
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- Details

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