Condensed Consolidated Statements of Financial Condition (Unaudited) (Parenthetical) (USD $)	Sep. 30, 2012	Dec. 31, 2011
Class A Common Stock
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	500,000	500,000
Common stock, shares issued	133,035	115,217
Common stock, shares outstanding	114,993	97,220
Treasury stock, at cost, shares of Class A common stock	18,042	17,997
Class B Common Stock
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	100,000	100,000
Common stock, shares issued	34,848	34,848
Common stock, shares outstanding	34,848	34,848