CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Statement Of Financial Position [Abstract]
Investment securities held to maturity	$ 6,223	$ 6,391
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	35,000,000	35,000,000
Common Stock, shares, issued	12,735,919	12,688,224
Common stock, shares outstanding	12,735,919	12,688,224
Common stock, unvested restricted shares	10,435	15,913