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