Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018
Earnings Per Share
Net income (loss)	$ 10,035	$ (6,951)	$ 12,928	$ (22,618)	$ 3,084	$ (9,690)
Weighted average shares outstanding - basic	37,299,766		36,790,401		37,151,694	36,645,248
Effect of potentially dilutive restricted stock units and options	588,000		614,000		738,000
Weighted average shares outstanding - diluted	37,887,559		37,404,360		37,889,586	36,645,248
Total anti-dilutive shares (in shares)	0		54,467		0	119,881
Basic and diluted:
Basic income (loss) per share	$ 0.27		$ 0.35		$ 0.08	$ (0.26)
Diluted income (loss) per share	$ 0.26		$ 0.35		$ 0.08	$ (0.26)
Unvested restricted stock units and unexercised options
Earnings Per Share
Total anti-dilutive shares (in shares)					669,641

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 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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