Investments (Net realized investment gains (losses)) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Net realized investment gains (losses)	$ 37	$ 1	$ 69	$ 10
Fixed maturity securities [Member]
Gross realized gains	51	47	124	119
Gross realized losses	(12)	(45)	(66)	(97)
Net realized investment gains (losses)	39	2	58	22
Equity securities [Member]
Gross realized gains	1	3	6	10
Gross realized losses	(4)	(5)	(4)	(27)
Net realized investment gains (losses)	(3)	(2)	2	(17)
Derivative [Member]
Net realized investment gains (losses)		(1)	1	(4)
Short term investments and other [Member]
Net realized investment gains (losses)	$ 1	$ 2	$ 8	$ 9