Insurance Premiums (Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011 years	Dec. 31, 2010 years	Dec. 31, 2011 Non Variable Interest Entities [Member]	Dec. 31, 2010 Non Variable Interest Entities [Member]	Dec. 31, 2009 Non Variable Interest Entities [Member]
Premiums receivable			$ 1,360	$ 1,589	$ 2,021
Weighted average risk-free rate	2.80%	3.10%
Weighted average expected collection term of the premiums receivable, years	9.13	9.16
Reinsurance premiums payable			$ 64	$ 71