CONSOLIDATED STATEMENTS OF FINANCIAL CONDITION (UNAUDITED) (Parenthetical) - $ / shares	Sep. 30, 2019	Dec. 31, 2018
Stockholders' Equity:
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	9,000,000	9,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	125,000,000	125,000,000
Common stock, shares issued (in shares)	53,699,694	53,690,825
Common stock, shares outstanding (in shares)	35,951,652	36,081,455
Treasury stock (in shares)	17,748,042	17,609,370