Reinsurance (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Property-liability insurance claims and claims expense
Reductions to costs and expenses due to reinsurance ceded amounts
Reinsurance ceded amount	$ 154	$ 188	$ 596	$ 327
Life and annuity contract benefits
Reductions to costs and expenses due to reinsurance ceded amounts
Reinsurance ceded amount	117	184	288	388
Interest credited to contractholder funds
Reductions to costs and expenses due to reinsurance ceded amounts
Reinsurance ceded amount	8	7	22	21
Property-liability insurance premiums earned
Reductions to premiums and contract charges due to reinsurance premium ceded amounts
Reinsurance premium ceded amounts	254	272	801	813
Life and annuity premiums and contract charges
Reductions to premiums and contract charges due to reinsurance premium ceded amounts
Premiums and contract charges	$ 160	$ 161	$ 482	$ 500