Investments (Net Realized Gains (Losses) And Losses Included In Net Realized Gains (Losses) And Other Comprehensive Income) (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Investments, Debt and Equity Securities [Abstract]
OTTI on fixed maturities, gross									$ (142)	$ (64)	$ (18)
OTTI on fixed maturities recognized in OCI (pre-tax)									39	7	0
OTTI on fixed maturities, net									(103)	(57)	(18)
Fixed maturities, Gross realized gains excluding OTTI									158	213	237
Fixed maturities, Gross realized losses excluding OTTI									(235)	(133)	(129)
Total fixed maturities									(180)	23	90
OTTI on equity securities									(7)	(8)	(2)
Equity securities, Gross realized gains excluding OTTI									47	22	21
Equity securities, Gross realized losses excluding OTTI									(11)	(61)	(4)
Total equity securities									29	(47)	15
OTTI on other investments									(2)	(3)	(2)
Foreign exchange losses									(80)	(40)	29
Investment and embedded derivative instruments									32	(107)	78
Fair value adjustments on insurance derivative									(203)	(217)	878
S&P put options and futures									(10)	(168)	(579)
Other derivative instruments									(12)	50	(2)
Other									6	2	(3)
Total net realized gains (losses)	$ (60)	$ (397)	$ 126	$ (89)	$ (210)	$ (120)	$ (73)	$ (104)	(420)	(507)	504
Change in net unrealized appreciation (depreciation) on investments, Fixed maturities available for sale									(1,119)	734	(1,798)
Change in net unrealized appreciation (depreciation) on investments, Fixed maturities held to maturity									43	(2)	(82)
Change in net unrealized appreciation (depreciation) on investments, Equity securities									(17)	77	(41)
Change in net unrealized appreciation (depreciation) on investments, Other									(36)	35	54
Change in net unrealized appreciation (depreciation) on investments, Income tax expense									152	(167)	408
Change in net unrealized appreciation on investments,									(977)	677	(1,459)
Total net realized gains (losses) and change in net unrealized appreciation (depreciation) on investments									$ (1,397)	$ 170	$ (955)