Loss Per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Basic and diluted net loss per common share calculation
Net loss	$ (13,209)	$ (22,204)	$ (26,282)	$ (65,326)
Weighted average common shares outstanding - basic and dilutive (in shares)	36,188	35,858	36,171	35,831
Net loss per common shares - basic and diluted (in dollars per share)	$ (0.37)	$ (0.62)	$ (0.73)	$ (1.82)
Anti-dilutive securities
Total (in shares)	5,017	4,340	5,017	4,340
Stock options outstanding
Anti-dilutive securities
Total (in shares)	4,818	3,805	4,818	3,805
Restricted stock units
Anti-dilutive securities
Total (in shares)	199	535	199	535

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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-Publisher FASB
-Name Accounting Standards Codification
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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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