Investments (Net Realized Gains (Losses) And Losses Included In Net Realized Gains (Losses) And Other Comprehensive Income) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Investments, Debt and Equity Securities [Abstract]
Document Fiscal Year Focus			2013
OTTI on fixed maturities, gross	$ (4)	$ (10)	$ (11)	$ (18)
OTTI on fixed maturities recognized in OCI (pre-tax)	0	0	0	0
OTTI on fixed maturities, net	(4)	(10)	(11)	(18)
Fixed maturities, Gross realized gains excluding OTTI	37	71	163	287
Fixed maturities, Gross realized losses excluding OTTI	(16)	(14)	(68)	(120)
Total fixed maturities	17	47	84	149
OTTI on equity securities	0	0	(1)	(5)
Equity securities, Gross realized gains excluding OTTI	8	3	18	5
Equity securities, Gross realized losses excluding OTTI	(1)	(1)	(4)	(2)
Total equity securities	7	2	13	(2)
OTTI on other investments	0	0	(2)	(7)
Foreign exchange gains (losses)	(26)	(50)	45	(64)
Investment and embedded derivative instruments	4	4	62	(3)
Fair value adjustments on insurance derivative	134	83	563	44
S&P put options and futures	(95)	(147)	(413)	(308)
Other derivative instruments	(1)	0	(2)	(4)
Other	0	1	0	1
Total net realized gains (losses)	$ 40	$ (60)	$ 350	$ (194)