Goodwill and Other Intangible Assets - Changes in the Carrying Amount of Goodwill by Reportable Segment (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended
Sep. 30, 2012	Sep. 30, 2011
Beginning balance	$ 6,344	$ 6,323
Goodwill, Acquired During Period	32	20
Goodwill, Intersegment Transfers	0
Contingent consideration		1
Goodwill, Impairment Loss	(7)
Ending balance	6,369	6,344
Retail Banking
Beginning balance	4,854	4,854
Goodwill, Acquired During Period	0	0
Goodwill, Intersegment Transfers	(4,854)
Contingent consideration		0
Goodwill, Impairment Loss	0
Ending balance	0	4,854
Diversified Commercial Banking
Beginning balance	928	928
Goodwill, Acquired During Period	0	0
Goodwill, Intersegment Transfers	(928)
Contingent consideration		0
Goodwill, Impairment Loss	0
Ending balance	0	928
Corporate and Investment Banking Segment [Member]
Beginning balance	180	180
Goodwill, Acquired During Period	0	0
Goodwill, Intersegment Transfers	(180)
Contingent consideration		0
Goodwill, Impairment Loss	0
Ending balance	0	180
Wealth and Investment Management Segment
Beginning balance	382	361
Goodwill, Acquired During Period	0	20
Goodwill, Intersegment Transfers	(382)
Contingent consideration		1
Goodwill, Impairment Loss	0
Ending balance	0	382
Consumer Banking and Private Wealth Management Segment [Member]
Beginning balance	0	0
Goodwill, Acquired During Period	32	0
Goodwill, Intersegment Transfers	3,930
Contingent consideration		0
Goodwill, Impairment Loss	0
Ending balance	3,962	0
Wholesale Banking [Member]
Beginning balance	0	0
Goodwill, Acquired During Period	0	0
Goodwill, Intersegment Transfers	2,414
Contingent consideration		0
Goodwill, Impairment Loss	(7)
Ending balance	2,407	0
Consumer Banking and Private Wealth Management Segment [Member] \| Retail Banking
Goodwill, Intersegment Transfers	3,600
Consumer Banking and Private Wealth Management Segment [Member] \| Wealth and Investment Management Segment
Goodwill, Intersegment Transfers	335
Wholesale Banking [Member] \| Retail Banking
Goodwill, Intersegment Transfers	1,300
Wholesale Banking [Member] \| Wealth and Investment Management [Member]
Goodwill, Intersegment Transfers	47
Wholesale Banking [Member] \| Corporate and Investment Banking Segment [Member]
Goodwill, Intersegment Transfers	$ 180

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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-Name Statement of Financial Accounting Standard (FAS)

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

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+ Details

- Definition

The aggregate amount of goodwill acquired in the period and allocated to the reportable segment. The value is stated at fair value based on the purchase price allocation.

+ References+ Details

- Definition

Loss recognized during the period that results from the write-down of goodwill after comparing the implied fair value of reporting unit goodwill with the carrying amount of that goodwill. Goodwill is assessed at least annually for impairment.

+ References

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Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

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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.

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+ Details