Investments (Details 6) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment losses	$ (82,000,000)	$ (288,000,000)	$ (238,000,000)	$ (538,000,000)
Portion of loss recognized in other comprehensive income	(4,000,000)	(18,000,000)	(31,000,000)	(23,000,000)
Net other-than-temporary impairment losses recognized in earnings	(86,000,000)	(306,000,000)	(269,000,000)	(561,000,000)
Fixed income securities
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment losses	(60,000,000)	(221,000,000)	(188,000,000)	(422,000,000)
Portion of loss recognized in other comprehensive income	(4,000,000)	(18,000,000)	(31,000,000)	(23,000,000)
Net other-than-temporary impairment losses recognized in earnings	(64,000,000)	(239,000,000)	(219,000,000)	(445,000,000)
Municipal
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment losses	(15,000,000)	(68,000,000)	(42,000,000)	(105,000,000)
Portion of loss recognized in other comprehensive income	(1,000,000)	4,000,000	(3,000,000)	4,000,000
Net other-than-temporary impairment losses recognized in earnings	(16,000,000)	(64,000,000)	(45,000,000)	(101,000,000)
Corporate
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment losses		(6,000,000)	(5,000,000)	(53,000,000)
Portion of loss recognized in other comprehensive income		(1,000,000)	1,000,000	2,000,000
Net other-than-temporary impairment losses recognized in earnings		(7,000,000)	(4,000,000)	(51,000,000)
Foreign government
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment losses			(1,000,000)
Net other-than-temporary impairment losses recognized in earnings			(1,000,000)
Residential mortgage-backed securities ("RMBS")
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment losses	(35,000,000)	(124,000,000)	(107,000,000)	(212,000,000)
Portion of loss recognized in other comprehensive income		5,000,000	(25,000,000)	(2,000,000)
Net other-than-temporary impairment losses recognized in earnings	(35,000,000)	(119,000,000)	(132,000,000)	(214,000,000)
Commercial mortgage-backed securities ("CMBS")
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment losses	(10,000,000)	(17,000,000)	(26,000,000)	(43,000,000)
Portion of loss recognized in other comprehensive income	(3,000,000)	(11,000,000)	(7,000,000)	(11,000,000)
Net other-than-temporary impairment losses recognized in earnings	(13,000,000)	(28,000,000)	(33,000,000)	(54,000,000)
Asset-backed securities ("ABS")
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment losses		(6,000,000)	(7,000,000)	(9,000,000)
Portion of loss recognized in other comprehensive income		(15,000,000)	3,000,000	(16,000,000)
Net other-than-temporary impairment losses recognized in earnings		(21,000,000)	(4,000,000)	(25,000,000)
Equity securities
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment losses	(13,000,000)	(31,000,000)	(33,000,000)	(37,000,000)
Net other-than-temporary impairment losses recognized in earnings	(13,000,000)	(31,000,000)	(33,000,000)	(37,000,000)
Mortgage loans
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment losses	(7,000,000)	(28,000,000)	(13,000,000)	(47,000,000)
Net other-than-temporary impairment losses recognized in earnings	(7,000,000)	(28,000,000)	(13,000,000)	(47,000,000)
Limited partnership interests
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment losses	(1,000,000)	(8,000,000)	(2,000,000)	(32,000,000)
Net other-than-temporary impairment losses recognized in earnings	(1,000,000)	(8,000,000)	(2,000,000)	(32,000,000)
Other:
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment losses	(1,000,000)		(2,000,000)
Net other-than-temporary impairment losses recognized in earnings	$ (1,000,000)		$ (2,000,000)