Unaudited Consolidated Statements of Financial Condition (Parenthetical) - $ / shares	Mar. 31, 2018	Dec. 31, 2017
Common stock, shares outstanding	76,987,641	75,569,845
Class A Common Stock
Common stock, par value per share	$ 0.01	$ 0.01
Common stock, shares authorized	500,000,000	500,000,000
Common stock, shares outstanding	53,483,634	50,463,126
Class B Common Stock
Common stock, par value per share	$ 0.01	$ 0.01
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares outstanding	9,707,506	11,922,192
Class C Common Stock
Common stock, par value per share	$ 0.01	$ 0.01
Common stock, shares authorized	400,000,000	400,000,000
Common stock, shares outstanding	13,796,501	13,184,527