Claim and Claim Adjustment Expense Reserves (Narrative) (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
Claim and Claim Adjustment Expense Reserves [Abstract]
Catastrophe losses net of reinsurance	$ 42	$ 27	$ 146	$ 123