Condensed Consolidated and Combined Statements of Financial Condition (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Accounts receivable, allowance for doubtful accounts	$ 1,776	$ 1,552
Investments at fair value, cost basis	$ 112,986	$ 39,999
Treasury Stock, Shares	242,619	0
Class A common stock
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common Stock, Shares Authorized	1,000,000,000	1,000,000,000
Common Stock, Shares, Issued	20,400,849	19,770,893
Common Stock, Shares, Outstanding	20,158,230	19,770,893
Class B common stock
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common Stock, Shares Authorized	1,000,000,000	1,000,000,000
Common Stock, Shares, Issued	31,358,729	31,621,542
Common Stock, Shares, Outstanding	31,358,729	31,621,542