CONSOLIDATED STATEMENTS OF FINANCIAL CONDITION (Parenthetical) - $ / shares	Sep. 30, 2021	Dec. 31, 2020
Shareholders' equity:
Preferred stock - par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock - shares authorized (in shares)	50,000,000	50,000,000
Preferred stock - shares issued (in shares)	0	0
Common stock - par value (in dollars per share)	$ 0.01	$ 0.01
Common stock - shares authorized (in shares)	100,000,000	100,000,000
Common stock - shares issued (in shares)	25,038,054	25,087,976
Common stock - shares outstanding (in shares)	25,038,054	25,087,976