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, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Net Loss per Share—Basic
Average common shares outstanding		34,437	33,749	34,111	33,527
Net Loss		$ (16,619)	$ (12,717)	$ (15,887)	$ (26,603)
Net earnings (loss) per common share		$ (0.48)	$ (0.38)	$ (0.47)	$ (0.79)
Net Loss per Share—Assuming Dilution
Average common shares outstanding		34,437	33,749	34,111	33,527
Stock options and awards		42	15	87	12
Average common shares assuming dilution		34,479	33,764	34,198	33,539
Net Loss		$ (16,619)	$ (12,717)	$ (15,887)	$ (26,603)
Net earnings (loss) per per common share—assuming dilution (in dollars per share)	[1]	$ (0.48)	$ (0.38)	$ (0.47)	$ (0.79)

[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.