Investments (Details 6) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment losses	$ (96)	$ (39)	$ (178)	$ (195)
Portion of loss recognized in other comprehensive income	8	(7)	(7)	16
Net other-than-temporary impairment losses recognized in earnings	(88)	(46)	(185)	(179)
Fixed income securities
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment losses	(19)	(11)	(57)	(125)
Portion of loss recognized in other comprehensive income	8	(7)	(7)	16
Net other-than-temporary impairment losses recognized in earnings	(11)	(18)	(64)	(109)
Municipal
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment losses	(6)	(2)	(23)	(28)
Portion of loss recognized in other comprehensive income		(3)	(5)	14
Net other-than-temporary impairment losses recognized in earnings	(6)	(5)	(28)	(14)
Asset-backed securities ("ABS")
Other-than-temporary impairment losses by asset type
Portion of loss recognized in other comprehensive income			(1)
Net other-than-temporary impairment losses recognized in earnings			(1)
Corporate
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment losses		(1)		(19)
Portion of loss recognized in other comprehensive income		(1)		(2)
Net other-than-temporary impairment losses recognized in earnings		(2)		(21)
Residential mortgage-backed securities ("RMBS")
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment losses	(4)	(4)	(5)	(59)
Portion of loss recognized in other comprehensive income	4	(6)	2	(2)
Net other-than-temporary impairment losses recognized in earnings		(10)	(3)	(61)
Commercial mortgage-backed securities ("CMBS")
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment losses	(9)	(4)	(29)	(19)
Portion of loss recognized in other comprehensive income	4	3	(3)	6
Net other-than-temporary impairment losses recognized in earnings	(5)	(1)	(32)	(13)
Equity securities
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment losses	(67)	(22)	(118)	(58)
Net other-than-temporary impairment losses recognized in earnings	(67)	(22)	(118)	(58)
Mortgage loans
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment losses	(6)	(1)	11	3
Net other-than-temporary impairment losses recognized in earnings	(6)	(1)	11	3
Limited partnership interests
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment losses	(2)	(2)	(10)	(5)
Net other-than-temporary impairment losses recognized in earnings	(2)	(2)	(10)	(5)
Other
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment losses	(2)	(3)	(4)	(10)
Net other-than-temporary impairment losses recognized in earnings	$ (2)	$ (3)	$ (4)	$ (10)