Non-recurring Fair Value Measurements (Details 3) (USD $) In Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010	Dec. 31, 2010
Non-Recurring Fair Value Measurements
Fair value on a non-recurring basis of financial investments					$ 2
Impairment charge for financial investments	0	0	0	(33)
Private Equity Funds [Member] | Quoted Market Prices (Level 1) [Member]
Non-Recurring Fair Value Measurements
Fair value on a non-recurring basis of financial investments					0
Quoted Market Prices (Level 1) [Member]
Non-Recurring Fair Value Measurements
Fair value on a non-recurring basis of financial investments					0
Private Equity Funds [Member] | Significant Other Observable Inputs (Level 2) [Member]
Non-Recurring Fair Value Measurements
Fair value on a non-recurring basis of financial investments					0
Significant Other Observable Inputs (Level 2) [Member]
Non-Recurring Fair Value Measurements
Fair value on a non-recurring basis of financial investments					0
Private Equity Funds [Member] | Significant Unobservable Inputs (Level 3) [Member]
Non-Recurring Fair Value Measurements
Fair value on a non-recurring basis of financial investments					2
Significant Unobservable Inputs (Level 3) [Member]
Non-Recurring Fair Value Measurements
Fair value on a non-recurring basis of financial investments					2
Private Equity Funds [Member] | Total Gains (Losses) [Member]
Non-Recurring Fair Value Measurements
Impairment charge for financial investments					(4)
Other private investments [Member] | Total Gains (Losses) [Member]
Non-Recurring Fair Value Measurements
Impairment charge for financial investments					(2)
Total Gains (Losses) [Member]
Non-Recurring Fair Value Measurements
Impairment charge for financial investments					(6)
Private Equity Funds [Member]
Non-Recurring Fair Value Measurements
Fair value on a non-recurring basis of financial investments					2
Impairment charge for financial investments	0	0	0	3
Other private investments [Member]
Non-Recurring Fair Value Measurements
Impairment charge for financial investments	$ 0	$ 0	$ 0	$ 2	$ 0