Invested Assets - Change in Unrealized Appreciation or Depreciation of Investments Carried at Fair Value (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Investments, Debt and Equity Securities [Abstract]
Change in unrealized appreciation of fixed maturities	$ (561)	$ 255	$ (409)	$ 617
Change in unrealized appreciation of equity securities	(16)	111	(1)	110
Net unrealized gains (losses) recognized in other comprehensive income, Before Tax	(577)	366	(410)	727
Deferred income tax (credit)	(202)	128	(144)	254
Net unrealized gains (losses) recognized in other comprehensive income, Net of Tax	$ (375)	$ 238	$ (266)	$ 473