Investments (Net realized investment gains (losses)) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Net realized investment gains (losses)	$ (14)	$ (14)	$ 32	$ 9
Fixed maturity securities [Member]
Gross realized gains	20	33	73	72
Gross realized losses	(39)	(40)	(54)	(52)
Net realized investment gains (losses)	(19)	(7)	19	20
Equity securities [Member]
Gross realized gains		5	5	7
Gross realized losses		(7)		(22)
Net realized investment gains (losses)		(2)	5	(15)
Derivative [Member]
Net realized investment gains (losses)	1	(5)	1	(3)
Short term investments and other [Member]
Net realized investment gains (losses)	$ 4		$ 7	$ 7