Fair Value (Details 6) (USD $) In Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Mortgage loans, net [Member]
Estimated fair value of certain investments
Carrying Value Prior to Measurement	$ 221	$ 159	$ 213	$ 237
Estimated Fair Value After Measurement	229	167	229	221
Net Investment Gain (Losses)	8	8	16	(16)
Held-for-investment [Member]
Estimated fair value of certain investments
Carrying Value Prior to Measurement	174	69	165	148
Estimated Fair Value After Measurement	182	83	182	138
Net Investment Gain (Losses)	8	14	17	(10)
Held-for-sale [Member]
Estimated fair value of certain investments
Carrying Value Prior to Measurement	47	90	48	89
Estimated Fair Value After Measurement	47	84	47	83
Net Investment Gain (Losses)	0	(6)	(1)	(6)
Other limited partnership interests [Member]
Estimated fair value of certain investments
Carrying Value Prior to Measurement	13	25	13	25
Estimated Fair Value After Measurement	10	17	10	17
Net Investment Gain (Losses)	(3)	(8)	(3)	(8)
Real estate joint ventures [Member]
Estimated fair value of certain investments
Carrying Value Prior to Measurement	0	7	0	33
Estimated Fair Value After Measurement	0	3	0	8
Net Investment Gain (Losses)	$ 0	$ (4)	$ 0	$ (25)