Investments (Components of other-than-temporary impairment losses recognized in earnings) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Other-than-temporary impairment losses recognized in earnings	$ 78	$ 154	$ 216
Corporate and other bonds [Member]
Other-than-temporary impairment losses recognized in earnings	22	27	95
States, municipalities and political subdivisions [Member]
Other-than-temporary impairment losses recognized in earnings		34
Residential mortgage-backed [Member]
Other-than-temporary impairment losses recognized in earnings	19	50	105
Other asset-backed [Member]
Other-than-temporary impairment losses recognized in earnings	2		6
Total asset-backed [Member]
Other-than-temporary impairment losses recognized in earnings	21	50	111
U.S. Treasury and obligations of government-sponsored enterprises [Member]
Other-than-temporary impairment losses recognized in earnings		1
Total fixed maturity securities available-for-sale [Member]
Other-than-temporary impairment losses recognized in earnings	43	112	206
Common stock [Member]
Other-than-temporary impairment losses recognized in earnings	8	6	8
Preferred stock [Member]
Other-than-temporary impairment losses recognized in earnings	26	36	1
Total equity securities available-for-sale [Member]
Other-than-temporary impairment losses recognized in earnings	34	42	9
Short term investments [Member]
Other-than-temporary impairment losses recognized in earnings	$ 1		$ 1