Condensed Consolidated Statements of Financial Condition (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Statement of Financial Position [Abstract]
Cash and cash equivalents, restricted from use	$ 6,955	$ 6,927
Fees receivable, allowance for doubtful accounts	100	300
Property and equipment, accumulated depreciation	$ 20,400	$ 20,100
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)	51,901,458	50,621,563
Common stock, shares outstanding (shares)	18,283,436	18,066,226
Treasury stock, par value (usd per share)	$ 0.01	$ 0.01
Treasury stock, shares (shares)	33,618,022	32,555,337