Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Basic
Net income	$ 8,092	$ 6,307
Weighted-average common shares outstanding	12,233,016	12,252,461
Basic earnings per share	$ 0.66	$ 0.51
Diluted
Net Income	$ 8,092	$ 6,307
Weighted-average common shares outstanding	12,233,016	12,252,461
Effect of dilutive restricted stock and stock appreciation rights	189,084	179,341
Weighted-average common shares outstanding assuming dilution	12,422,100	12,431,802
Diluted earnings per share	$ 0.65	$ 0.51