Fair Value Measurements (Financial Instruments Measured At Fair Value Using Significant Unobservable Inputs) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2012		Jun. 30, 2011		Jun. 30, 2012		Jun. 30, 2011		Dec. 31, 2011	Mar. 31, 2011	Dec. 31, 2010
Equity Securities [Member]
Schedule Of Fair Value Measurements [Line Items]
Balance- Beginning of Period, Assets	$ 10		$ 10		$ 13		$ 13
Transfers into Level 3
Transfers out of Level 3
Change in Net Unrealized Gains (Losses) included in OCI, Assets					1		(1)
Net Realized Gains/Losses			2				4
Purchases	2		2		3		2
Sales			(4)		(5)		(8)
Settlements
Balance-End of Period	12		10		12		10
Net Realized Gains/Losses Attributable to Changes in Fair Value at the Balance Sheet Date
Other Long-term Investments [Member]
Schedule Of Fair Value Measurements [Line Items]
Balance- Beginning of Period, Assets	1,954		1,564		1,877		1,432
Transfers into Level 3
Transfers out of Level 3
Change in Net Unrealized Gains (Losses) included in OCI, Assets	16		9		24		51
Net Realized Gains/Losses	(5)		(3)		(7)		(3)
Purchases	132		243		245		333
Sales			(55)		(1)		(55)
Settlements	(50)		(78)		(91)		(78)
Balance-End of Period	2,047		1,680		2,047		1,680
Net Realized Gains/Losses Attributable to Changes in Fair Value at the Balance Sheet Date	(5)		(3)		(7)		(3)
Other Derivative Instruments [Member]
Schedule Of Fair Value Measurements [Line Items]
Balance- Beginning of Period, Assets	(1)				3		4			4
Transfers into Level 3
Transfers out of Level 3
Change in Net Unrealized Gains (Losses) included in OCI, Assets
Net Realized Gains/Losses	(1)				(4)		1
Purchases	3				3
Sales
Settlements					(1)		(1)
Balance-End of Period	1		4		1		4			4
Net Realized Gains/Losses Attributable to Changes in Fair Value at the Balance Sheet Date					(1)		1
Available-for-sale Securities [Member] | U.S. Treasury And Agency [Member]
Schedule Of Fair Value Measurements [Line Items]
Balance- Beginning of Period, Assets					5
Transfers into Level 3	5
Transfers out of Level 3
Change in Net Unrealized Gains (Losses) included in OCI, Assets
Net Realized Gains/Losses
Purchases
Sales
Settlements	(1)				(1)
Balance-End of Period	4				4
Net Realized Gains/Losses Attributable to Changes in Fair Value at the Balance Sheet Date
Available-for-sale Securities [Member] | Foreign [Member]
Schedule Of Fair Value Measurements [Line Items]
Balance- Beginning of Period, Assets	49		26		33		26
Transfers into Level 3	1		5		1		9
Transfers out of Level 3			(6)		(1)		(7)
Change in Net Unrealized Gains (Losses) included in OCI, Assets							(1)
Net Realized Gains/Losses			1				1
Purchases	6		5		40		5
Sales	(35)		(2)		(52)		(3)
Settlements	(1)		(2)		(1)		(3)
Balance-End of Period	20		27		20		27
Net Realized Gains/Losses Attributable to Changes in Fair Value at the Balance Sheet Date
Available-for-sale Securities [Member] | Corporate Securities [Member]
Schedule Of Fair Value Measurements [Line Items]
Balance- Beginning of Period, Assets	117		113		134		115
Transfers into Level 3	28		29		28		34
Transfers out of Level 3	(2)				(9)		(4)
Change in Net Unrealized Gains (Losses) included in OCI, Assets	1				3		1
Net Realized Gains/Losses	(1)		(1)		(1)		(2)
Purchases	5		3		8		22
Sales	(7)		(1)		(15)		(20)
Settlements	(4)		(1)		(11)		(4)
Balance-End of Period	137		142		137		142
Net Realized Gains/Losses Attributable to Changes in Fair Value at the Balance Sheet Date
Available-for-sale Securities [Member] | Mortgage Backed-Securities [Member]
Schedule Of Fair Value Measurements [Line Items]
Balance- Beginning of Period, Assets	19		81		28		39
Transfers into Level 3	12		3		12		4
Transfers out of Level 3	(3)		(35)		(15)		(35)
Change in Net Unrealized Gains (Losses) included in OCI, Assets
Net Realized Gains/Losses
Purchases					4		46
Sales			(12)				(15)
Settlements	(1)		(3)		(2)		(5)
Balance-End of Period	27		34		27		34
Net Realized Gains/Losses Attributable to Changes in Fair Value at the Balance Sheet Date
Available-for-sale Securities [Member] | States, Municipalities, And Political Subdivisions [Member]
Schedule Of Fair Value Measurements [Line Items]
Balance- Beginning of Period, Assets	1				1		2			1
Transfers into Level 3	1				1
Transfers out of Level 3
Change in Net Unrealized Gains (Losses) included in OCI, Assets
Net Realized Gains/Losses
Purchases
Sales
Settlements	(1)				(1)		(1)
Balance-End of Period	1		1		1		1			1
Net Realized Gains/Losses Attributable to Changes in Fair Value at the Balance Sheet Date
Guaranteed Minimum Income Benefit [Member]
Schedule Of Fair Value Measurements [Line Items]
Balance- Beginning of Period, Assets	863	[1]	449	[2]	1,319	[1]	507	[3]
Transfers into Level 3		[1]		[2]
Transfers out of Level 3		[1]		[2]
Change in Net Unrealized Gains (Losses) included in OCI, Assets		[1]		[2]
Net Realized Gains/Losses	491	[1]	75	[2]	35	[1]	17	[3]
Purchases		[1]		[2]
Sales		[1]		[2]
Settlements		[1]		[2]
Balance-End of Period	1,354	[1]	524	[2],[3]	1,354	[1]	524	[2],[3]
Net Realized Gains/Losses Attributable to Changes in Fair Value at the Balance Sheet Date	491	[1]	75	[2]	35	[1]	17	[3]
Reported liabilities	1,600		676		1,600		676		1,500	596	648
Guaranteed minimum benefits fair value derivative adjustment in liability	$ 1,400		$ 524		$ 1,400		$ 524		$ 1,300	$ 449	$ 507

[1] Our GLB reinsurance product meets the definition of a derivative instrument for accounting purposes and is accordingly carried at fair value. Excluded from the table above is the portion of the GLB derivative liability classified as Future policy benefits in the consolidated balance sheets. Refer to Note 5 for additional information.

[2] Discussion of the most significant inputs used in the fair value measurement of GLB and the sensitivity of those assumptions is included within Note 5 Guaranteed living benefits.

[3] Our GLB reinsurance product meets the definition of a derivative instrument for accounting purposes and is accordingly carried at fair value. Excluded from the table above is the portion of the GLB derivative liability classified as Future policy benefits in the consolidated balance sheets. The liability for GLB reinsurance was $676 million at June 30, 2011, and $648 million at December 31, 2010, which includes a fair value derivative adjustment of $524 million and $507 million, respectively.