Investments (Net Realized Gains (Losses) And Losses Included In Net Realized Gains (Losses) And Other Comprehensive Income) (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Investments, Debt and Equity Securities [Abstract]
OTTI on fixed maturities, gross	$ 31	$ 5	$ 57	$ 20
OTTI on fixed maturities recognized in OCI (pre-tax)	5	1	11	3
OTTI on fixed maturities, net	(26)	(4)	(46)	(17)
Fixed maturities, Gross realized gains excluding OTTI	19	73	91	163
Fixed maturities, Gross realized losses excluding OTTI	(44)	(51)	(95)	(97)
Total fixed maturities	(51)	18	(50)	49
OTTI on equity securities	(3)	0	(4)	(7)
Equity securities, Gross realized gains excluding OTTI	10	4	43	8
Equity securities, Gross realized losses excluding OTTI	(5)	(60)	(7)	(61)
Total equity securities	2	(56)	32	(60)
OTTI on other investments	(1)	0	(1)	(3)
Foreign exchange losses	(2)	(19)	(73)	(42)
Investment and embedded derivative instruments	(22)	(13)	6	(53)
Fair value adjustments on insurance derivative	(396)	(80)	(337)	(126)
S&P put options and futures	83	(15)	69	(106)
Other derivative instruments	(9)	45	(10)	52
Other	(1)	0	4	(8)
Total net realized gains (losses) (includes $(49), $(38), $(18), and $(11) reclassified from AOCI)	$ (397)	$ (120)	$ (360)	$ (297)