Investments (Components of other-than-temporary impairment losses recognized in earnings) (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
Other-than-temporary impairment losses recognized in earnings	$ 10	$ 16	$ 17	$ 50
Corporate and other bonds [Member]
Other-than-temporary impairment losses recognized in earnings	6	8	9	16
Residential mortgage-backed [Member]
Other-than-temporary impairment losses recognized in earnings	2	2	4	5
Other asset-backed [Member]
Other-than-temporary impairment losses recognized in earnings		1	1	2
Total asset-backed [Member]
Other-than-temporary impairment losses recognized in earnings	2	3	5	7
Total fixed maturity securities available-for-sale [Member]
Other-than-temporary impairment losses recognized in earnings	8	11	14	23
Common stock [Member]
Other-than-temporary impairment losses recognized in earnings	2	3	3	5
Preferred stock [Member]
Other-than-temporary impairment losses recognized in earnings		2		22
Equity securities [Member]
Other-than-temporary impairment losses recognized in earnings	$ 2	$ 5	$ 3	$ 27