CONSOLIDATED STATEMENTS OF FINANCIAL CONDITION (Parenthetical) - $ / shares	Dec. 31, 2018	Dec. 31, 2017
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)	53,690,825	53,624,453
Common stock, shares outstanding (in shares)	36,081,455	37,419,070
Treasury stock (in shares)	17,609,370	16,205,383