Deferred Policy Acquisition Costs and Asset Reconciliation, Including the Amortized Deferred Policy Acquisition Costs (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Deferred policy acquisition costs asset, beginning of year	$ 488	$ 481	$ 509
Capitalized deferred policy acquisition costs	718	676	650
Amortized deferred policy acquisition costs	(685)	(653)	(638)
Amortized shadow deferred policy acquisition costs	(11)	(16)	(40)
Deferred policy acquisition costs asset, end of year	$ 510	$ 488	$ 481