Fair Value Measurements (Financial Instruments Measured At Fair Value Using Significant Unobservable Inputs) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013		Jun. 30, 2014		Dec. 31, 2013		Jun. 30, 2013		Dec. 31, 2012
Equity Securities [Member]
Schedule Of Fair Value Measurements [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3	$ 0		$ 0		$ 0		$ 7
Balance- Beginning of Period, Assets	2		4		4		3
Transfers out of Level 3, Assets	0		0		(2)		(1)
Change in Net Unrealized Gains (Losses) included in OCI, Assets	0		0		1		(5)
Net Realized Gains/Losses, Assets			0				4
Purchases, Assets	0		0		1		1
Sales, Assets	0		0		(2)		(5)
Settlements, Assets			0
Balance-End of Period, Assets	2		4		2		4
Net Realized Gains/Losses Attributable to Changes in Fair Value at the Balance Sheet Date, Assets			0
Short-term Investments [Member]
Schedule Of Fair Value Measurements [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3			1		0		8
Balance- Beginning of Period, Assets			9		7		0
Transfers out of Level 3, Assets			(2)		(7)		(2)
Purchases, Assets			0		0		2
Balance-End of Period, Assets	0		8		0		8
Other Long-term Investments [Member]
Schedule Of Fair Value Measurements [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3	0		0		0		0
Balance- Beginning of Period, Assets	2,640		2,349		2,440		2,252
Transfers out of Level 3, Assets			0
Change in Net Unrealized Gains (Losses) included in OCI, Assets	(8)		(1)		40		34
Net Realized Gains/Losses, Assets	0		0		(3)		(2)
Purchases, Assets	170		138		522		387
Sales, Assets	(3)		(1)		(6)		(10)
Settlements, Assets	(128)		(96)		(322)		(272)
Balance-End of Period, Assets	2,671		2,389		2,671		2,389
Net Realized Gains/Losses Attributable to Changes in Fair Value at the Balance Sheet Date, Assets	0		0		(3)		(2)
Available-for-sale Securities [Member] | Foreign [Member]
Schedule Of Fair Value Measurements [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3	1		1		3		33
Balance- Beginning of Period, Assets	12		48		44		60
Transfers out of Level 3, Assets	0		(8)		(34)		(49)
Change in Net Unrealized Gains (Losses) included in OCI, Assets	0		2		(1)		(2)
Net Realized Gains/Losses, Assets	0		0		1		1
Purchases, Assets	0		12		2		15
Sales, Assets	(1)		(13)		(3)		(15)
Settlements, Assets	0		0		0		(1)
Balance-End of Period, Assets	12		42		12		42
Available-for-sale Securities [Member] | Corporate Debt Securities [Member]
Schedule Of Fair Value Measurements [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3	5		12		35		29
Balance- Beginning of Period, Assets	204		114		166		102
Transfers out of Level 3, Assets	0		(1)		(22)		(30)
Change in Net Unrealized Gains (Losses) included in OCI, Assets	(1)		(1)		1		(1)
Net Realized Gains/Losses, Assets	2		(1)		2		(2)
Purchases, Assets	20		6		65		39
Sales, Assets	(9)		(4)		(17)		(4)
Settlements, Assets	(13)		(4)		(22)		(12)
Balance-End of Period, Assets	208		121		208		121
Available-for-sale Securities [Member] | Mortgage Backed-Securities [Member]
Schedule Of Fair Value Measurements [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3	0		0		0		0
Balance- Beginning of Period, Assets	7		9		8		13
Transfers out of Level 3, Assets	0		0		0		0
Change in Net Unrealized Gains (Losses) included in OCI, Assets			0
Net Realized Gains/Losses, Assets			0
Purchases, Assets	8		0		8		0
Sales, Assets	0		0		0		(3)
Settlements, Assets	0		0		(1)		(1)
Balance-End of Period, Assets	15		9		15		9
Guaranteed Minimum Income Benefit [Member]
Schedule Of Fair Value Measurements [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliations, Recurring Basis, Liability Value	317	[1]	514	[1]	317	[1]	514	[1]	241	[1]	193	[1]	652	[1]	1,119	[1]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings	76	[1]	(138)	[1]	124	[1]	(605)	[1]
Net Realized Gains/Losses Attributable to Changes in Fair Value at the Balance Sheet Date, Liabilities	76		(138)		124		(605)
Reported liabilities	$ 566		$ 746		$ 566		$ 746				$ 427		$ 880		$ 1,400

[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.