Investments (Available-For-Sale and Held-To-Maturity Securities In Consolidated Investment Portfolio) (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Fixed-Maturity Investments [Member]
Schedule of Investments [Line Items]
Amortized Cost	$ 4,883
Fair Value	4,993
Variable Interest Entity [Member]
Schedule of Investments [Line Items]
Amortized Cost	2,829	3,843
Fair Value	2,674	3,489
Variable Interest Entity [Member] \| Fixed-Maturity Investments [Member]
Schedule of Investments [Line Items]
Amortized Cost	427
Fair Value	415
Fair Value	2,674
HTM Investments [Member]
Schedule of Investments [Line Items]
Amortized Cost	2,829	3,843
Gross Unrealized Gains	2	17
Gross Unrealized Losses	(157)	(371)
Fair Value	2,674	3,489
Other-Than-Temporary Impairments
HTM Investments [Member] \| Corporate Obligations [Member] \| Variable Interest Entity [Member]
Schedule of Investments [Line Items]
Amortized Cost	2,829	2,840
Gross Unrealized Gains	2
Gross Unrealized Losses	(157)	(371)
Fair Value	2,674	2,469
Other-Than-Temporary Impairments
HTM Investments [Member] \| Other Asset-Backed [Member] \| Variable Interest Entity [Member] \| Asset-Backed Securities [Member]
Schedule of Investments [Line Items]
Amortized Cost		1,003
Gross Unrealized Gains		17
Fair Value		1,020
Other-Than-Temporary Impairments
AFS Investments [Member]
Schedule of Investments [Line Items]
Amortized Cost	6,122	9,025
Gross Unrealized Gains	251	263
Gross Unrealized Losses	(152)	(478)
Fair Value	6,221	8,810
Other-Than-Temporary Impairments	(20)	(139)
AFS Investments [Member] \| Fixed-Maturity Investments [Member]
Schedule of Investments [Line Items]
Amortized Cost	4,883	7,492
Gross Unrealized Gains	238	262
Gross Unrealized Losses	(128)	(418)
Fair Value	4,993	7,336
Other-Than-Temporary Impairments	(20)	(139)
AFS Investments [Member] \| U.S. Treasury And Government Agency [Member] \| Fixed-Maturity Investments [Member]
Schedule of Investments [Line Items]
Amortized Cost	819	1,091
Gross Unrealized Gains	40	39
Gross Unrealized Losses	(1)
Fair Value	858	1,130
AFS Investments [Member] \| State And Municipal Bonds [Member] \| Fixed-Maturity Investments [Member]
Schedule of Investments [Line Items]
Amortized Cost	1,446	2,025
Gross Unrealized Gains	97	76
Gross Unrealized Losses	(12)	(19)
Fair Value	1,531	2,082
AFS Investments [Member] \| State And Municipal Bonds [Member] \| Variable Interest Entity [Member]
Schedule of Investments [Line Items]
Amortized Cost	38
Gross Unrealized Gains	3
Fair Value	41
AFS Investments [Member] \| Foreign Governments [Member] \| Fixed-Maturity Investments [Member]
Schedule of Investments [Line Items]
Amortized Cost	183	350
Gross Unrealized Gains	13	24
Fair Value	196	374
AFS Investments [Member] \| Corporate Obligations [Member] \| Fixed-Maturity Investments [Member]
Schedule of Investments [Line Items]
Amortized Cost	1,058	1,674
Gross Unrealized Gains	54	42
Gross Unrealized Losses	(20)	(106)
Fair Value	1,092	1,610
Other-Than-Temporary Impairments	5	(2)
AFS Investments [Member] \| Corporate Obligations [Member] \| Variable Interest Entity [Member]
Schedule of Investments [Line Items]
Amortized Cost	177	2
Gross Unrealized Gains	9
Gross Unrealized Losses	(6)
Fair Value	180	2
AFS Investments [Member] \| Residential Mortgage-Backed Agency [Member] \| Mortgage-Backed Securities [Member] \| Fixed-Maturity Investments [Member]
Schedule of Investments [Line Items]
Amortized Cost	939	1,198
Gross Unrealized Gains	19	47
Gross Unrealized Losses	(1)
Fair Value	957	1,245
AFS Investments [Member] \| Residential Mortgage-Backed Non-Agency [Member] \| Mortgage-Backed Securities [Member] \| Fixed-Maturity Investments [Member]
Schedule of Investments [Line Items]
Amortized Cost	86	325
Gross Unrealized Gains	11	31
Gross Unrealized Losses	(8)	(83)
Fair Value	89	273
Other-Than-Temporary Impairments		(57)
AFS Investments [Member] \| Residential Mortgage-Backed Non-Agency [Member] \| Variable Interest Entity [Member] \| Mortgage-Backed Securities [Member]
Schedule of Investments [Line Items]
Amortized Cost	92	119
Gross Unrealized Losses	(10)	(26)
Fair Value	82	93
AFS Investments [Member] \| Commercial Mortgage-Backed [Member] \| Mortgage-Backed Securities [Member] \| Fixed-Maturity Investments [Member]
Schedule of Investments [Line Items]
Amortized Cost	46	58
Gross Unrealized Gains		1
Gross Unrealized Losses	(4)	(10)
Fair Value	42	49
AFS Investments [Member] \| Collateralized Debt Obligations [Member] \| Asset-Backed Securities [Member] \| Fixed-Maturity Investments [Member]
Schedule of Investments [Line Items]
Amortized Cost	161	251
Gross Unrealized Gains	1
Gross Unrealized Losses	(71)	(118)
Fair Value	91	133
Other-Than-Temporary Impairments	(25)	(43)
AFS Investments [Member] \| Collateralized Debt Obligations [Member] \| Variable Interest Entity [Member] \| Asset-Backed Securities [Member]
Schedule of Investments [Line Items]
Amortized Cost	97	112
Gross Unrealized Losses	(8)	(15)
Fair Value	89	97
AFS Investments [Member] \| Other Asset-Backed [Member] \| Asset-Backed Securities [Member] \| Fixed-Maturity Investments [Member]
Schedule of Investments [Line Items]
Amortized Cost	145	520
Gross Unrealized Gains	3	2
Gross Unrealized Losses	(11)	(82)
Fair Value	137	440
Other-Than-Temporary Impairments		(37)
AFS Investments [Member] \| Other Asset-Backed [Member] \| Variable Interest Entity [Member] \| Asset-Backed Securities [Member]
Schedule of Investments [Line Items]
Amortized Cost	23	41
Fair Value	23	41
AFS Investments [Member] \| Money Market Securities [Member]
Schedule of Investments [Line Items]
Amortized Cost	580	926
Fair Value	580	926
AFS Investments [Member] \| Money Market Securities [Member] \| Variable Interest Entity [Member]
Schedule of Investments [Line Items]
Amortized Cost	210	199
Fair Value	210	199
AFS Investments [Member] \| Equity Securities [Member]
Schedule of Investments [Line Items]
Amortized Cost	22	134
Gross Unrealized Gains	1	1
Gross Unrealized Losses		(19)
Fair Value	$ 23	$ 116

Cumulative other-than-temporary Impairment Of Securities Recognized in AOCI Since Adoption of Accounting Standard

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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.

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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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For an unclassified balance sheet, this item represents investments in debt securities which are categorized as held-to-maturity. The held-to-maturity category is for those securities that the entity has the positive intent and ability to hold until maturity.

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As of the balance sheet date, the excess of fair value over carrying value (amortized cost) of a debt security categorized as held-to-maturity, exclusive of dividend or interest income recognized but not yet received and exclusive of any write-downs for other-than-temporary impairment. Such item represents the gross unrecognized holding gain.

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As of the balance sheet date, the excess of carrying value (amortized cost) over fair value of a debt security categorized as held-to-maturity, exclusive of dividend or interest income recognized but not yet received and exclusive of any write-downs for other-than-temporary impairment. Such item represents the gross unrecognized holding loss.

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