Consolidated Statements of Financial Condition (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Statement of Financial Position [Abstract]
Cash and cash equivalents, restricted from use	$ 4,300	$ 4,700
Advisory fees receivable, allowance for doubtful accounts	0	300
Property and equipment, accumulated depreciation	$ 58,997	$ 58,517
Common stock, par value (usd per share)	$ 0.01	$ 0.01
Common stock, shares authorized (shares)	100,000,000	100,000,000
Common stock, shares issued (shares)	41,377,614	40,511,209
Common stock, shares outstanding (shares)	28,981,189	29,325,374
Exchangeable shares of subsidiary, shares issued (shares)	257,156	257,156
Exchangeable shares of subsidiary, shares outstanding (shares)	32,804	32,804
Treasury stock, par value (usd per share)	$ 0.01	$ 0.01
Treasury stock, shares (shares)	12,396,425	11,185,835