CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Statement Of Financial Position [Abstract]
Investment securities held to maturity	$ 6,391	$ 6,806
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	12,688,224	12,664,797
Common stock, shares outstanding	12,688,224	12,664,797