Investments (Components of other-than-temporary impairment losses recognized in earnings) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Other-than-temporary impairment losses recognized in earnings	$ 31	$ 5	$ 43	$ 7
Corporate and other bonds [Member]
Other-than-temporary impairment losses recognized in earnings	11	2	16	3
States, municipalities and political subdivisions [Member]
Other-than-temporary impairment losses recognized in earnings	13	0	18	0
Residential mortgage-backed [Member]
Other-than-temporary impairment losses recognized in earnings	5	1	6	2
Other asset-backed [Member]
Other-than-temporary impairment losses recognized in earnings	1	1	1	1
Total asset-backed [Member]
Other-than-temporary impairment losses recognized in earnings	6	2	7	3
Total fixed maturity securities available-for-sale [Member]
Other-than-temporary impairment losses recognized in earnings	30	4	41	6
Common Stock [Member]
Other-than-temporary impairment losses recognized in earnings	0	1	1	1
Short term investments [Member]
Other-than-temporary impairment losses recognized in earnings	$ 1	$ 0	$ 1	$ 0