Investments (Components of other-than-temporary impairment losses recognized in earnings) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Other-than-temporary impairment losses recognized in earnings	$ 12	$ 2
Corporate and other bonds [Member]
Other-than-temporary impairment losses recognized in earnings	5	1
States, municipalities and political subdivisions [Member]
Other-than-temporary impairment losses recognized in earnings	5	0
Residential mortgage-backed [Member]
Other-than-temporary impairment losses recognized in earnings	1	1
Total fixed maturity securities available-for-sale [Member]
Other-than-temporary impairment losses recognized in earnings	11	2
Common stock [Member]
Other-than-temporary impairment losses recognized in earnings	$ 1	$ 0