Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Earnings Per Share, [Line Items]
Net income	$ 11,940	$ 4,201	$ 29,339	$ 18,977
Earnings Per Share, Basic [Abstract]
Earnings per share - basic	$ 0.57	$ 0.20	$ 1.39	$ 0.90
Earnings Per Share, Diluted [Abstract]
Earnings per share - diluted	$ 0.55	$ 0.20	$ 1.35	$ 0.88
Weighted Average Number of Shares Outstanding, Basic [Abstract]
Weighted average shares outstanding - basic	21,102	20,995	21,073	20,978
Weighted Average Number of Shares Outstanding, Diluted [Abstract]
Weighted average shares outstanding - diluted	21,721	21,520	21,671	21,461
Stock option [Member]
Incremental Weighted Average Shares Attributable to Dilutive Effect [Abstract]
Dilutive effect of shares issued under stock compensation arrangements	602	525	595	483
Restricted stock [Member]
Incremental Weighted Average Shares Attributable to Dilutive Effect [Abstract]
Dilutive effect of shares issued under stock compensation arrangements	17	0	3	0