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Investments (Available-For-Sale In Consolidated Investment Portfolio) (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012		Dec. 31, 2011
Schedule of Investments [Line Items]
Amortized Cost	$ 6,729		$ 9,025
Gross Unrealized Gains	337		263
Gross Unrealized Losses	(191)		(478)
Fair Value	6,875		8,810
Other-Than-Temporary Impairments	(47)	[1]	(139)	[1]
Other Investments [Member]
Schedule of Investments [Line Items]
Amortized Cost	624		1,060
Gross Unrealized Gains			1
Gross Unrealized Losses			(19)
Fair Value	624		1,042
Fixed-Maturity Investments [Member]
Schedule of Investments [Line Items]
Amortized Cost	5,644		7,492
Gross Unrealized Gains	326		262
Gross Unrealized Losses	(161)		(418)
Fair Value	5,809		7,336
Other-Than-Temporary Impairments	(47)	[1]	(139)	[1]
Fixed-Maturity Investments [Member] | Variable Interest Entity [Member]
Schedule of Investments [Line Items]
Amortized Cost	446
Fair Value	427
Fixed-Maturity Investments [Member] | Mortgage-Backed Securities [Member]
Schedule of Investments [Line Items]
Amortized Cost	1,221
Fair Value	1,246
Fixed-Maturity Investments [Member] | Mortgage-Backed Securities [Member] | Variable Interest Entity [Member]
Schedule of Investments [Line Items]
Amortized Cost	99
Fair Value	87
Fixed-Maturity Investments [Member] | Asset-Backed Securities [Member]
Schedule of Investments [Line Items]
Amortized Cost	360
Fair Value	275
Fixed-Maturity Investments [Member] | Asset-Backed Securities [Member] | Variable Interest Entity [Member]
Schedule of Investments [Line Items]
Amortized Cost	133
Fair Value	123
Corporate Obligations [Member] | Variable Interest Entity [Member]
Schedule of Investments [Line Items]
Amortized Cost	177		2
Gross Unrealized Gains	7
Gross Unrealized Losses	(7)
Fair Value	177		2
Residential Mortgage-Backed Non-Agency [Member] | Mortgage-Backed Securities [Member] | Variable Interest Entity [Member]
Schedule of Investments [Line Items]
Amortized Cost	99		119
Gross Unrealized Losses	(12)		(26)
Fair Value	87		93
Collateralized Debt Obligations [Member] | Asset-Backed Securities [Member] | Variable Interest Entity [Member]
Schedule of Investments [Line Items]
Amortized Cost	108		112
Gross Unrealized Losses	(11)		(15)
Fair Value	97		97
Other Asset-Backed [Member] | Asset-Backed Securities [Member] | Variable Interest Entity [Member]
Schedule of Investments [Line Items]
Amortized Cost	25		41
Gross Unrealized Gains	1
Fair Value	26		41
State And Municipal Bonds [Member] | Asset-Backed Securities [Member] | Variable Interest Entity [Member]
Schedule of Investments [Line Items]
Amortized Cost	37
Gross Unrealized Gains	3
Fair Value	40
Perpetual Preferred Securities [Member] | Other Investments [Member]
Schedule of Investments [Line Items]
Amortized Cost	31		127
Gross Unrealized Losses			(19)
Fair Value	31		108
Other Investment Securities [Member] | Other Investments [Member]
Schedule of Investments [Line Items]
Amortized Cost	10		22
Gross Unrealized Gains			1
Fair Value	10		23
Money Market Securities [Member] | Other Investments [Member]
Schedule of Investments [Line Items]
Amortized Cost	583		911
Fair Value	583		911
Money Market Securities [Member] | Other Investments [Member] | Variable Interest Entity [Member]
Schedule of Investments [Line Items]
Amortized Cost	15		199
Fair Value	15		199
Taxable Bonds [Member] | Fixed-Maturity Investments [Member]
Schedule of Investments [Line Items]
Amortized Cost	4,758		6,370
Gross Unrealized Gains	266		221
Gross Unrealized Losses	(161)		(416)
Fair Value	4,863		6,175
Other-Than-Temporary Impairments	(47)	[1]	(139)	[1]
Taxable Bonds [Member] | U.S. Treasury And Government Agency [Member] | Fixed-Maturity Investments [Member]
Schedule of Investments [Line Items]
Amortized Cost	896		1,091
Gross Unrealized Gains	44		39
Gross Unrealized Losses	(1)
Fair Value	939		1,130
Taxable Bonds [Member] | Foreign Governments [Member] | Fixed-Maturity Investments [Member]
Schedule of Investments [Line Items]
Amortized Cost	318		326
Gross Unrealized Gains	22		23
Fair Value	340		349
Taxable Bonds [Member] | Corporate Obligations [Member] | Fixed-Maturity Investments [Member]
Schedule of Investments [Line Items]
Amortized Cost	1,068		1,698
Gross Unrealized Gains	59		43
Gross Unrealized Losses	(21)		(106)
Fair Value	1,106		1,635
Other-Than-Temporary Impairments	3	[1]	(2)	[1]
Taxable Bonds [Member] | Residential Mortgage-Backed Agency [Member] | Fixed-Maturity Investments [Member] | Mortgage-Backed Securities [Member]
Schedule of Investments [Line Items]
Amortized Cost	988		1,198
Gross Unrealized Gains	48		47
Fair Value	1,036		1,245
Taxable Bonds [Member] | Residential Mortgage-Backed Non-Agency [Member] | Fixed-Maturity Investments [Member] | Mortgage-Backed Securities [Member]
Schedule of Investments [Line Items]
Amortized Cost	187		325
Gross Unrealized Gains	16		31
Gross Unrealized Losses	(36)		(83)
Fair Value	167		273
Other-Than-Temporary Impairments	(24)	[1]	(57)	[1]
Taxable Bonds [Member] | Commercial Mortgage-Backed [Member] | Fixed-Maturity Investments [Member] | Mortgage-Backed Securities [Member]
Schedule of Investments [Line Items]
Amortized Cost	46		58
Gross Unrealized Gains	1		1
Gross Unrealized Losses	(4)		(10)
Fair Value	43		49
Taxable Bonds [Member] | Collateralized Debt Obligations [Member] | Fixed-Maturity Investments [Member] | Asset-Backed Securities [Member]
Schedule of Investments [Line Items]
Amortized Cost	165		251
Gross Unrealized Losses	(74)		(118)
Fair Value	91		133
Other-Than-Temporary Impairments	(26)	[1]	(43)	[1]
Taxable Bonds [Member] | Other Asset-Backed [Member] | Fixed-Maturity Investments [Member] | Asset-Backed Securities [Member]
Schedule of Investments [Line Items]
Amortized Cost	195		520
Gross Unrealized Gains	3		2
Gross Unrealized Losses	(14)		(82)
Fair Value	184		440
Other-Than-Temporary Impairments			(37)	[1]
Taxable Bonds [Member] | State And Municipal Bonds [Member] | Fixed-Maturity Investments [Member]
Schedule of Investments [Line Items]
Amortized Cost	895		903
Gross Unrealized Gains	73		35
Gross Unrealized Losses	(11)		(17)
Fair Value	957		921
Tax-Exempt Bonds [Member] | State And Municipal Bonds [Member] | Fixed-Maturity Investments [Member]
Schedule of Investments [Line Items]
Amortized Cost	886		1,122
Gross Unrealized Gains	60		41
Gross Unrealized Losses			(2)
Fair Value	$ 946		$ 1,161
[1] Represents unrealized gains or losses on other than temporarily impaired securities recognized in accumulated other comprehensive income (loss), which includes the non-credit component of impairments, as well as all subsequent changes in fair value of such impaired securities.

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

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

-Paragraph 19

-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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- Definition

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents Available-for-sale Securities which consist of all investments in certain debt and equity securities neither classified as trading or held-to-maturity securities. A debt security represents a creditor relationship with an enterprise. Debt securities include, among other items, US Treasury securities, US government securities, municipal securities, corporate bonds, convertible debt, commercial paper, and all securitized debt instruments. An equity security represents an ownership interest in an enterprise or the right to acquire or dispose of an ownership interest in an enterprise at fixed or determinable prices. Equity securities include, among other things, common stock, certain preferred stock, warrant rights, call options, and put options, but do not include convertible debt. An entity may opt to provide the reader with additional narrative text to better understand the nature of investments in debt and equity securities which are categorized as Available-for-sale.

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-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.



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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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