Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Numerator:
Net Earnings	$ (3,206)	$ 3,559	$ (2,591)	$ (3,957)	$ 15,370	$ 11,477	$ 15,328	$ 4,439	$ (6,195)	$ 46,614	$ 32,088
Basic - Weighted Average Shares Outstanding									17,695,390	17,523,267	18,015,151
Effect of dilutive securities									0	452,916	478,296
Diluted - Weighted Average Shares Outstanding									17,695,390	17,976,183	18,493,447
Basic Earnings per Share	$ (0.18)	$ 0.20	$ (0.15)	$ (0.22)	$ 0.88	$ 0.66	$ 0.88	$ 0.25	$ (0.35)	$ 2.66	$ 1.78
Diluted (in dollars per share)	$ (0.18)	$ 0.20	$ (0.15)	$ (0.22)	$ 0.85	$ 0.64	$ 0.85	$ 0.25	$ (0.35)	$ 2.59	$ 1.74
Anti-dilutive securities excluded from earnings per share calculation (in shares)									711,212	356,598	222,092

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

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The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of share based payment arrangements using the treasury stock method.

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The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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The average number of shares or units issued and outstanding that are used in calculating diluted EPS or earnings per unit (EPU), determined based on the timing of issuance of shares or units in the period.

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