Investments (Details 6) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment losses	$ (55)	$ (69)	$ (82)	$ (156)
Portion of loss recognized in other comprehensive income	(5)	19	(15)	23
Net other-than-temporary impairment losses recognized in earnings	(60)	(50)	(97)	(133)
Fixed income securities
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment losses	(6)	(46)	(38)	(114)
Portion of loss recognized in other comprehensive income	(5)	19	(15)	23
Net other-than-temporary impairment losses recognized in earnings	(11)	(27)	(53)	(91)
Municipal
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment losses	(4)	(25)	(17)	(26)
Portion of loss recognized in other comprehensive income	(3)	17	(5)	17
Net other-than-temporary impairment losses recognized in earnings	(7)	(8)	(22)	(9)
Asset-backed securities ("ABS")
Other-than-temporary impairment losses by asset type
Portion of loss recognized in other comprehensive income	(1)		(1)
Net other-than-temporary impairment losses recognized in earnings	(1)		(1)
Corporate
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment losses				(18)
Portion of loss recognized in other comprehensive income		(1)		(1)
Net other-than-temporary impairment losses recognized in earnings		(1)		(19)
Residential mortgage-backed securities ("RMBS")
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment losses	(1)	(12)	(1)	(55)
Portion of loss recognized in other comprehensive income	(1)		(2)	4
Net other-than-temporary impairment losses recognized in earnings	(2)	(12)	(3)	(51)
Commercial mortgage-backed securities ("CMBS")
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment losses	(1)	(9)	(20)	(15)
Portion of loss recognized in other comprehensive income		3	(7)	3
Net other-than-temporary impairment losses recognized in earnings	(1)	(6)	(27)	(12)
Equity securities
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment losses	(32)	(20)	(51)	(36)
Net other-than-temporary impairment losses recognized in earnings	(32)	(20)	(51)	(36)
Mortgage loans
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment losses	(9)	7	17	4
Net other-than-temporary impairment losses recognized in earnings	(9)	7	17	4
Limited partnership interests
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment losses	(8)	(1)	(8)	(3)
Net other-than-temporary impairment losses recognized in earnings	(8)	(1)	(8)	(3)
Other
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment losses		(9)	(2)	(7)
Net other-than-temporary impairment losses recognized in earnings		$ (9)	$ (2)	$ (7)