Fair Value Measurements (Schedule Of Significant Unobservable Inputs Used In Level 3 Liability Valuations) (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2015		Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Valuation Technique	[1]	Actuarial model
Minimum
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Significant Unobservable Inputs Lapse rate	[1]	1.00%
Annuitization rate	[1]	0.00%
Maximum
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Significant Unobservable Inputs Lapse rate	[1]	30.00%
Annuitization rate	[1]	55.00%
Guaranteed Living Benefits [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
GLB liability		$ 888		$ 663		$ 427		$ 1,400
Guaranteed Minimum Death Benefit
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
GLB liability		117		111
Guaranteed Minimum Income Benefit
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value	[1]	609
Balance - beginning of year, liabilities		406	[2],[3]	193	[3],[4]	1,119	[4]
Transfers Into Level 3, liabilities				0	[3]	0	[4]
Transfers out of Level 3, liabilities				0	[3]	0	[4]
Change in Net Unrealized Gains (Losses) included in OCI, Liabilities	[3]			0
Net Realized Gains/Losses, Liabilities		203	[2]	213	[3]	(926)	[4]
Purchased, liabilities				0	[3]	0	[4]
Sales, liabilities				0	[3]	0	[4]
Settlements, liabilities				0	[3]	0	[4]
Balance - end of year, liabilities		609	[2]	406	[2],[3]	193	[3],[4]
Net Realized Gains/Losses Attributable to Changes in Fair Value at the Balance Sheet Date, Liabilities		203	[2]	213	[3]	(926)	[4]
Equity securities
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance, beginning of year, assets		2		4		3
Transfers into Level 3, assets						8
Transfers out of Level 3, assets				(2)		(1)
Change in Net Unrealized Gains (Losses) included in OCI, Assets		3				6
Net Realized Gains/Losses, Assets		(2)				4
Purchased, assets		13		2		2
Sales, assets				(2)		(6)
Balance, end of year, assets		16		2		4
Net Realized Gains/Losses Attributable to Changes in Fair Value at the Balance Sheet Date, Assets		(2)
Short-term investments
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance, beginning of year, assets				7
Transfers into Level 3, assets						8
Transfers out of Level 3, assets				(7)		(2)
Purchased, assets						3
Sales, assets						(1)
Settlements, assets						(1)
Balance, end of year, assets						7
Other Long-term Investments [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance, beginning of year, assets		204		196		180
Change in Net Unrealized Gains (Losses) included in OCI, Assets		(6)		1		(2)
Purchased, assets		33		20		29
Settlements, assets		(19)		(11)		(11)
Balance, end of year, assets		212		204		196
Other Derivative Instruments
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance - beginning of year, liabilities		4
Transfers Into Level 3, liabilities				2
Net Realized Gains/Losses, Liabilities		2		2
Balance - end of year, liabilities		6		4
Net Realized Gains/Losses Attributable to Changes in Fair Value at the Balance Sheet Date, Liabilities		2		2
Fixed maturities available for sale | Foreign Government Debt Securities [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance, beginning of year, assets		22		44		60
Transfers into Level 3, assets		34		10		36
Transfers out of Level 3, assets				(34)		(54)
Change in Net Unrealized Gains (Losses) included in OCI, Assets		(2)		1		0
Net Realized Gains/Losses, Assets		1		3		(1)
Purchased, assets		15		15		24
Sales, assets		(3)		(4)		(21)
Settlements, assets		(8)		(5)		(2)
Balance, end of year, assets		57		22		44
Net Realized Gains/Losses Attributable to Changes in Fair Value at the Balance Sheet Date, Assets		(1)		(4)		0
Fixed maturities available for sale | Corporate securities
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance, beginning of year, assets		187		166		102
Transfers into Level 3, assets		16		37		47
Transfers out of Level 3, assets				(23)		(31)
Change in Net Unrealized Gains (Losses) included in OCI, Assets		(1)		1		0
Net Realized Gains/Losses, Assets		4		5		2
Purchased, assets		52		73		75
Sales, assets		(28)		(38)		(7)
Settlements, assets		(48)		(22)		(18)
Balance, end of year, assets		174		187		166
Net Realized Gains/Losses Attributable to Changes in Fair Value at the Balance Sheet Date, Assets		(2)		(5)		(2)
Fixed maturities available for sale | Mortgage backed-securities
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance, beginning of year, assets		15		8		13
Purchased, assets		41		8		0
Sales, assets		(2)				(3)
Settlements, assets		(1)		(1)		(2)
Balance, end of year, assets		$ 53		$ 15		$ 8

[1] Discussion of the most significant inputs used in the fair value measurement of GLB and the sensitivity of those assumptions is included within Note 4 a) Guaranteed living benefits.

[2] 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 c) for additional information.

[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 $663 million at December 31, 2014 and $427 million at December 31, 2013, which includes a fair value derivative adjustment of $406 million and $193 million, respectively.

[4] 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 $427 million at December 31, 2013 and $1.4 billion at December 31, 2012, which includes a fair value derivative adjustment of $193 million and $1.1 billion, respectively.