Earned Life Insurance Premiums on Ceded Business (Detail) (Life Insurance Segment, USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Life Insurance Segment
Direct earned premiums	$ 220	$ 211	$ 196
Assumed earned premiums
Ceded earned premiums	(55)	(53)	(53)
Net earned premiums	$ 165	$ 158	$ 143