Condensed Consolidated Statements of Financial Condition (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Statement of Financial Position [Abstract]
Cash and cash equivalents, restricted from use	$ 5,881	$ 6,938
Fees receivable, allowance for doubtful accounts	0	100
Property and equipment, accumulated depreciation	$ 18,100	$ 15,600
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)	55,321,470	53,288,909
Common stock, shares outstanding (shares)	18,815,295	17,768,705
Treasury stock, par value (usd per share)	$ 0.01	$ 0.01
Treasury stock, shares (shares)	36,506,175	35,520,204