Claim and Claim Adjustment Expense Reserves (Net prior year claim and claim adjustment expense reserve development) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Decrease in provision for insured events of prior years	$ (36)	$ (115)	$ (182)
Property and casualty reserve development [Member]
Decrease in provision for insured events of prior years	(39)	(115)	(180)
Life reserve development in life company [Member]
Decrease in provision for insured events of prior years	$ 3		$ (2)