INVESTMENTS - Net Effect on Shareholders' Equity of Unrealized Gains and Losses from Investment Securities (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Net Effect on Shareholders' Equity of Unrealized Gains and Losses from Investment Securities [Abstract]
Unrealized gains (losses) on securities available for sale	$ 2,219	$ 1,761
Unamortized unrealized gains on securities transferred to held to maturity	29	34
Deferred income taxes	(800)	(652)
Shareholders' equity, unrealized gains (losses) on investment securities	$ 1,448	$ 1,143

Accumulated appreciation or loss, net of tax, in value of the total of available-for-sale securities at the end of an accounting period.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 220

-SubTopic 10

-Section 45

-Paragraph 13

-URI http://asc.fasb.org/extlink&oid=6920043&loc=d3e653-108580

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 130

-Paragraph 26

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 Accounting Standards Codification

-Topic 220

-SubTopic 10

-Section 45

-Paragraph 11

-URI http://asc.fasb.org/extlink&oid=6920043&loc=d3e637-108580

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 220

-SubTopic 10

-Section 45

-Paragraph 14

-URI http://asc.fasb.org/extlink&oid=6920043&loc=d3e681-108580

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Data Type:	xbrli:monetaryItemType
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