Carrying amount as of the balance sheet date, which is the cumulative amount paid and (if applicable) the fair value of any noncontrolling interest in the acquiree, adjusted for any amortization recognized prior to the adoption of any changes in generally accepted accounting principles (as applicable) and for any impairment charges, in excess of the fair value of net assets acquired in one or more business combination transactions.

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Reference 5: http://www.xbrl.org/2003/role/presentationRef

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 7: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Goodwill and Other Intangible Assets - Changes in the Carrying Amount of Goodwill by Reportable Segment (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Goodwill [Line Items]
Goodwill	$ 6,344	$ 6,369	$ 6,369	$ 6,344
Goodwill, Intersegment Transfers	0
Retail Banking [Member]
Goodwill [Line Items]
Goodwill	0			4,854
Goodwill, Intersegment Transfers	(4,854)
Diversified Commercial Banking [Member]
Goodwill [Line Items]
Goodwill	0			928
Goodwill, Intersegment Transfers	(928)
Corporate and Investment Banking [Member]
Goodwill [Line Items]
Goodwill	0			180
Goodwill, Intersegment Transfers	(180)
Wealth and Investment Management [Member]
Goodwill [Line Items]
Goodwill	0			382
Goodwill, Intersegment Transfers	(382)
Consumer Banking and Private Wealth Management [Member]
Goodwill [Line Items]
Goodwill	3,930			0
Goodwill, Intersegment Transfers	3,930
Wholesale Banking [Member]
Goodwill [Line Items]
Goodwill	2,414			0
Goodwill, Intersegment Transfers	$ 2,414