Condensed Consolidated Statements Of Financial Condition (Parenthetical) (USD $)	Jun. 30, 2011	Dec. 31, 2010
Treasury stock, shares of Class A common stock	17,951,000	17,936,000
Class A Common Stock [Member]
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	500,000,000	500,000,000
Common stock, shares issued	103,906,000	88,192,000
Common stock, shares outstanding	85,955,000	70,256,000
Class B Common Stock [Member]
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	34,848,000	25,848,000
Common stock, shares outstanding	34,848,000	25,848,000