Net Earnings (Loss) Per Common Share - Computation of Basic and Diluted Net Earnings Per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Net Earnings (Loss) per Share—Basic:
Average common shares outstanding									34,875	34,266	33,594
Net Loss	$ 1,938	$ (22,759)	$ (10,698)	$ (14,044)	$ (5,117)	$ (7,276)	$ (16,619)	$ 732	$ (45,563)	$ (28,280)	$ (53,327)
Net earnings per common share	$ 0.06	$ (0.65)	$ (0.31)	$ (0.41)	$ (0.15)	$ (0.21)	$ (0.48)	$ 0.02	$ (1.31)	$ (0.83)	$ (1.59)
Diluted
Average common shares outstanding									34,875	34,266	33,594
Stock options and awards									399	109	48
Average common shares assuming dilution									35,274	34,375	33,642
Net Loss	$ 1,938	$ (22,759)	$ (10,698)	$ (14,044)	$ (5,117)	$ (7,276)	$ (16,619)	$ 732	$ (45,563)	$ (28,280)	$ (53,327)
Net Earnings (loss) per Share - Assuming Dilution (in dollars per share)	$ 0.05	$ (0.65)	$ (0.31)	$ (0.41)	$ (0.15)	$ (0.21)	$ (0.48)	$ 0.02	$ (1.31)	$ (0.83)	$ (1.59)