Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Basic
Net income	$ 7,509	$ 6,513	$ 15,601	$ 12,820
Weighted-average common shares outstanding	12,239,901	12,268,481	12,236,478	12,260,515
Basic earnings per share	$ 0.61	$ 0.53	$ 1.27	$ 1.05
Diluted
Net Income	$ 7,509	$ 6,513	$ 15,601	$ 12,820
Weighted-average common shares outstanding	12,239,901	12,268,481	12,236,478	12,260,515
Effect of dilutive restricted stock and stock appreciation rights	205,281	181,009	197,227	180,180
Weighted-average common shares outstanding assuming dilution	12,445,182	12,449,490	12,433,705	12,440,695
Diluted earnings per share	$ 0.6	$ 0.52	$ 1.25	$ 1.03