Fair Value (Details 6) (Non Recurring [Member], USD $) In Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Held-for-investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value Prior to Measurement	$ 289	$ 93	$ 273	$ 90
Estimated Fair Value After Measurement	245	93	245	93
Net Investment Gain (Losses)	(44)	0	(28)	3
Held-for-sale [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value Prior to Measurement	71	27	72	28
Estimated Fair Value After Measurement	68	28	68	28
Net Investment Gain (Losses)	(3)	1	(4)	0
Mortgage loans, net [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value Prior to Measurement	360	120	345	118
Estimated Fair Value After Measurement	313	121	313	121
Net Investment Gain (Losses)	(47)	1	(32)	3
Other limited partnership interests [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value Prior to Measurement	5	3	18	28
Estimated Fair Value After Measurement	3	1	13	18
Net Investment Gain (Losses)	(2)	(2)	(5)	(10)
Real estate joint ventures [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value Prior to Measurement	0	0	0	33
Estimated Fair Value After Measurement	0	0	0	8
Net Investment Gain (Losses)	0	0	0	(25)
Goodwill [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value Prior to Measurement	65	0	65	0
Estimated Fair Value After Measurement	0	0	0	0
Net Investment Gain (Losses)	$ (65)	$ 0	$ (65)	$ 0