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, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Investments, Debt and Equity Securities [Abstract]
OTTI on fixed maturities, gross	$ (7)	$ (31)	$ (85)	$ (57)
OTTI on fixed maturities recognized in OCI (pre-tax)	0	5	8	11
OTTI on fixed maturities, net	(7)	(26)	(77)	(46)
Gross realized gains excluding OTTI	47	19	149	91
Gross realized losses excluding OTTI	(13)	(44)	(228)	(95)
Fixed Maturities Net Realized Gains Losses Total	27	(51)	(156)	(50)
Other Than Temporary Impairment on Equity Securities	(1)	(3)	(7)	(4)
Equity securities, Gross realized gains excluding OTTI	19	10	63	43
Equity securities, Gross realized losses excluding OTTI	(12)	(5)	(17)	(7)
Equity Securities Net Realized Gains Losses Total	6	2	39	32
Other Than Temporary Impairment on Other Investment	(4)	(1)	(7)	(1)
Foreign exchange gains (losses)	29	(2)	46	(73)
Investment and embedded derivative instruments	1	(22)	(85)	6
Fair value adjustments on insurance derivative	89	(396)	(270)	(337)
S&P put options and futures	(45)	83	(88)	69
Other derivative instruments	3	(9)	1	(10)
Other	(6)	(1)	10	4
Total net realized gains (losses) (includes $33, $(49), $(117), and $(18) reclassified from AOCI)	$ 100	$ (397)	$ (510)	$ (360)