Net Earnings (Loss) Per Common Share Computation of Basic and Diluted Net Earnings (Loss) Per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Net Earnings (Loss) per Share—Basic
Average common shares outstanding		33,749	33,169	33,527	33,040
Net Loss		$ (12,717)	$ (16,543)	$ (26,603)	$ (30,651)
Net earnings (loss) per common share		$ (0.38)	$ (0.50)	$ (0.79)	$ (0.93)
Net Earnings (Loss) per Share—Assuming Dilution
Average common shares outstanding		33,749	33,169	33,527	33,040
Stock options and awards		15	827	12	827
Average common shares assuming dilution		33,764	33,996	33,539	33,867
Net Loss		$ (12,717)	$ (16,543)	$ (26,603)	$ (30,651)
Net earnings (loss) per per common share—assuming dilution (in dollars per share)	[1]	$ (0.38)	$ (0.50)	$ (0.79)	$ (0.93)

[1] Net loss per common share assuming dilution calculated utilizing weighted average shares outstanding-basic for the periods in which there was a net loss.