Consolidated Statements of Financial Condition (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Allowance for loan losses (in dollars)	$ 4,069	$ 4,603
Stockholders' Equity:
Treasury stock, shares	2,617,826	2,617,826
Preferred stock
Stockholders' Equity:
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized	1,000,000	1,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common Stock
Stockholders' Equity:
Common stock, shares issued	30,069,045	30,039,043
Common Stock | Voting common stock
Stockholders' Equity:
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	50,000,000	50,000,000
Common stock, shares issued	21,312,649	21,282,647
Common stock, shares outstanding	18,694,823	18,664,821
Common Stock | Non-voting common stock
Stockholders' Equity:
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	25,000,000	25,000,000
Common stock, shares issued	8,756,396	8,756,396
Common stock, shares outstanding	8,756,396	8,756,396