Invested Assets - Realized Investment Gains and Losses (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Investments Debt And Equity Securities [Abstract]
Fixed maturities, Gross realized gains	$ 69	$ 14	$ 77	$ 27
Fixed maturities, Gross realized losses	(17)	(8)	(28)	(10)
Fixed maturities, Other-than-temporary impairment losses	(4)		(4)
Total fixed maturities	48	6	45	17
Equity securities, Gross realized gains	23	119	89	174
Equity securities, Other-than-temporary impairment losses	(1)	(5)	(1)	(7)
Total equity securities	22	114	88	167
Other invested assets	55	59	108	133
Total Realized Investment Gains, Net	$ 125	$ 179	$ 241	$ 317