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
		Mar. 31, 2018	Mar. 31, 2017
Net Earnings (Loss) per Share—Basic
Average common shares outstanding		32,911	32,475
Net Loss		$ (14,108)	$ (16,780)
Net earnings (loss) per common share		$ (0.43)	$ (0.52)
Net Earnings (Loss) per Share—Assuming Dilution
Average common shares outstanding		32,911	32,475
Stock options and awards		888	229
Average common shares assuming dilution		33,799	32,704
Net Loss		$ (14,108)	$ (16,780)
Net earnings (loss) per per common share—assuming dilution (in dollars per share)	[1]	$ (0.43)	$ (0.52)

[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.