Details of Holdings of Perpetual Securities (Detail) (USD $) In Millions	Jun. 30, 2011	Dec. 31, 2010
Investment Holdings [Line Items]
Amortized Cost	$ 58,548	$ 55,951
Fair Value	59,632	55,890
Perpetual Securities
Investment Holdings [Line Items]
Amortized Cost	7,259	7,827
Fair Value	7,103	7,512
Unrealized Gain (Loss)	(156)	(315)
Perpetual Securities \| A \| Upper Tier II
Investment Holdings [Line Items]
Amortized Cost	3,247	3,279
Fair Value	3,260	3,250
Unrealized Gain (Loss)	13	(29)
Perpetual Securities \| A \| Tier I
Investment Holdings [Line Items]
Amortized Cost	601	632
Fair Value	524	568
Unrealized Gain (Loss)	(77)	(64)
Perpetual Securities \| Upper Tier II
Investment Holdings [Line Items]
Amortized Cost	4,758	5,285
Fair Value	4,789	5,091
Unrealized Gain (Loss)	31	(194)
Perpetual Securities \| Upper Tier II \| AA
Investment Holdings [Line Items]
Amortized Cost	192	190
Fair Value	204	201
Unrealized Gain (Loss)	12	11
Perpetual Securities \| Upper Tier II \| BBB
Investment Holdings [Line Items]
Amortized Cost	1,051	1,274
Fair Value	1,057	1,164
Unrealized Gain (Loss)	6	(110)
Perpetual Securities \| Upper Tier II \| BB or Lower
Investment Holdings [Line Items]
Amortized Cost	268	542
Fair Value	268	476
Unrealized Gain (Loss)	0	(66)
Perpetual Securities \| Tier I
Investment Holdings [Line Items]
Amortized Cost	2,501	2,542
Fair Value	2,314	2,421
Unrealized Gain (Loss)	(187)	(121)
Perpetual Securities \| Tier I \| BBB
Investment Holdings [Line Items]
Amortized Cost	1,531	1,386
Fair Value	1,446	1,296
Unrealized Gain (Loss)	(85)	(90)
Perpetual Securities \| Tier I \| BB or Lower
Investment Holdings [Line Items]
Amortized Cost	369	524
Fair Value	344	557
Unrealized Gain (Loss)	$ (25)	$ 33

For an unclassified balance sheet, this item represents investments in debt and equity securities which are categorized neither as held-to-maturity nor trading.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6871852&loc=d3e26610-111562

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 115
-Paragraph 12
-Subparagraph b
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 FASB Staff Position (FSP)
-Number FAS115-1/124-1
-Paragraph 15E
-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 133
-Paragraph 22
-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 FASB Staff Position (FSP)
-Number FAS115-1/124-1
-Paragraph 15D
-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 Statement of Financial Accounting Standard (FAS)
-Number 115
-Paragraph 13
-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
-Name FASB Staff Position (FSP)
-Number FAS115-1/124-1
-Paragraph 15C
-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 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 115
-Paragraph 14
-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 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 115
-Paragraph 16
-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 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 25
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6379932&loc=d3e22054-111558

+ Details

- Definition

This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

+ References+ Details