Insurance Premiums (Narrative) (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012 Non Variable Interest Entities [Member]	Dec. 31, 2011 Non Variable Interest Entities [Member]	Dec. 31, 2010 Non Variable Interest Entities [Member]
Premiums receivable			$ 1,228	$ 1,360	$ 1,589
Weighted average risk-free rate	2.60%	2.80%
Weighted average expected collection term of the premiums receivable, years	9 years 1 month 17 days	9 years 1 month 17 days
Reinsurance premiums payable			$ 59	$ 64