Investments (Details 6) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment losses	$ (69)	$ (82)	$ (156)	$ (238)
Portion of loss recognized in other comprehensive income	19	(4)	23	(31)
Net other-than-temporary impairment losses recognized in earnings	(50)	(86)	(133)	(269)
Fixed income securities
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment losses	(46)	(60)	(114)	(188)
Portion of loss recognized in other comprehensive income	19	(4)	23	(31)
Net other-than-temporary impairment losses recognized in earnings	(27)	(64)	(91)	(219)
Municipal
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment losses	(25)	(15)	(26)	(42)
Portion of loss recognized in other comprehensive income	17	(1)	17	(3)
Net other-than-temporary impairment losses recognized in earnings	(8)	(16)	(9)	(45)
Corporate
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment losses			(18)	(5)
Portion of loss recognized in other comprehensive income	(1)		(1)	1
Net other-than-temporary impairment losses recognized in earnings	(1)		(19)	(4)
Foreign government
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment losses				(1)
Net other-than-temporary impairment losses recognized in earnings				(1)
Residential mortgage-backed securities ("RMBS")
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment losses	(12)	(35)	(55)	(107)
Portion of loss recognized in other comprehensive income			4	(25)
Net other-than-temporary impairment losses recognized in earnings	(12)	(35)	(51)	(132)
Commercial mortgage-backed securities ("CMBS")
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment losses	(9)	(10)	(15)	(26)
Portion of loss recognized in other comprehensive income	3	(3)	3	(7)
Net other-than-temporary impairment losses recognized in earnings	(6)	(13)	(12)	(33)
Asset-backed securities ("ABS")
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment losses				(7)
Portion of loss recognized in other comprehensive income				3
Net other-than-temporary impairment losses recognized in earnings				(4)
Equity securities
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment losses	(20)	(13)	(36)	(33)
Net other-than-temporary impairment losses recognized in earnings	(20)	(13)	(36)	(33)
Mortgage loans
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment losses	7	(7)	4	(13)
Net other-than-temporary impairment losses recognized in earnings	7	(7)	4	(13)
Limited partnership interests
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment losses	(1)	(1)	(3)	(2)
Net other-than-temporary impairment losses recognized in earnings	(1)	(1)	(3)	(2)
Other
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment losses	(9)	(1)	(7)	(2)
Net other-than-temporary impairment losses recognized in earnings	$ (9)	$ (1)	$ (7)	$ (2)