Income (Loss) Per Common Share - Basic and Diluted (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Income (Loss) Per Share
Net income (loss)	$ (18,530)	$ (15,827)
Net income (loss) per common share:
Basic (in dollars per share)	$ (0.40)	$ (0.34)
Diluted (in dollars per share)	$ (0.40)	$ (0.34)
Weighted average shares reconciliation
Basic weighted average shares outstanding	46,848	46,963
Diluted weighted average shares outstanding	46,848	46,963