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, 2011
Beginning balance	$ 6,344	$ 6,323
Goodwill, Intersegment Transfers	0
Contingent consideration		1
Ending balance	6,344	6,324
Retail Banking
Beginning balance	4,854	4,854
Goodwill, Intersegment Transfers	(4,854)
Contingent consideration		0
Ending balance	0	4,854
Diversified Commercial Banking
Beginning balance	928	928
Goodwill, Intersegment Transfers	(928)
Contingent consideration		0
Ending balance	0	928
Corporate and Investment Banking Segment [Member]
Beginning balance	180	180
Goodwill, Intersegment Transfers	(180)
Contingent consideration		0
Ending balance	0	180
Wealth and Investment Management Segment
Beginning balance	382	361
Goodwill, Intersegment Transfers	(382)
Contingent consideration		1
Ending balance	0	362
Consumer Banking and Private Wealth Management Segment [Member]
Beginning balance	0	0
Goodwill, Intersegment Transfers	3,930
Contingent consideration		0
Ending balance	3,930	0
Wholesale Banking [Member]
Beginning balance	0	0
Goodwill, Intersegment Transfers	2,414
Contingent consideration		0
Ending balance	2,414	0
Consumer Banking and Private Wealth Management Segment [Member] \| Retail Banking
Goodwill, Intersegment Transfers	3,596
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	1,259
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.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 142

-Paragraph 45

-Subparagraph e

-Clause 1

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 142

-Paragraph 43

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 141R

-Paragraph 68

-Subparagraph l

-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 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 142

-Paragraph 45

-Subparagraph e

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 141R

-Paragraph 34

-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

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6905597&loc=d3e13816-109267

Reference 7: 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

Reference 8: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 141R

-Paragraph 72

-Subparagraph d

-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