Deferred Acquisition Costs - Deferred Policy Acquisition Costs and Asset Reconciliation (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Deferred policy acquisition costs asset at beginning of period	$ 491	$ 483	$ 470	$ 477
Capitalized deferred policy acquisition costs	203	192	401	362
Amortized deferred policy acquisition costs	(183)	(181)	(362)	(337)
Amortized shadow deferred policy acquisition costs	35	(10)	37	(18)
Deferred policy acquisition costs asset at end of period	$ 546	$ 484	$ 546	$ 484