Deferred Policy Acquisition Costs (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Summary of deferred policy acquisition costs
Deferred policy acquisition costs	$ 916	$ 901
Property and Casualty Insurance [Member]
Summary of deferred policy acquisition costs
Policy acquisition costs	191	189
Annuity and Supplemental Insurance [Member]
Summary of deferred policy acquisition costs
Policy acquisition costs	922	898
Policyholder sales inducements	203	207
Present value of future profits ("PVFP")	139	144
Impact of unrealized gains and losses on securities	(539)	(537)
Deferred policy acquisition costs	$ 725	$ 712