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	$ (15)	$ (9)	$ (16)	$ (42)
Portion of loss recognized in other comprehensive income	(2)	3	(10)
Net other-than-temporary impairment losses recognized in earnings	(17)	(6)	(26)	(42)
Fixed income securities
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment losses	(1)	(15)	(26)	(46)
Portion of loss recognized in other comprehensive income	(2)	3	(10)
Net other-than-temporary impairment losses recognized in earnings	(3)	(12)	(36)	(46)
Municipal
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment losses	(1)		(8)
Net other-than-temporary impairment losses recognized in earnings	(1)		(8)
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		(1)		(14)
Net other-than-temporary impairment losses recognized in earnings		(1)		(14)
RMBS
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment losses		(5)	1	(17)
Portion of loss recognized in other comprehensive income			(1)	(3)
Net other-than-temporary impairment losses recognized in earnings		(5)		(20)
CMBS
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment losses		(9)	(19)	(15)
Portion of loss recognized in other comprehensive income	(1)	3	(8)	3
Net other-than-temporary impairment losses recognized in earnings	(1)	(6)	(27)	(12)
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
Equity securities
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment losses	(1)		(1)
Net other-than-temporary impairment losses recognized in earnings	(1)		(1)
Limited partnership interests
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment losses	(4)	(1)	(4)	(2)
Net other-than-temporary impairment losses recognized in earnings	(4)	(1)	(4)	(2)
Other
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment losses			(2)	2
Net other-than-temporary impairment losses recognized in earnings			$ (2)	$ 2