CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Statement [Abstract]
Net sales	$ 764,041	$ 837,398	$ 785,897
Cost of sales	619,166	684,978	631,358
Gross profit	144,875	152,420	154,539
Selling, product development and administrative expenses	129,928	126,272	103,054
Impairment of goodwill and other long-lived assets	61,109	64,206	0
Restructuring expenses	15,903	767	2,297
Operating (loss) income	(62,065)	(38,825)	49,188
Employee benefit plans settlement expenses	385	25,247	0
Interest expense	15,979	14,262	6,212
Other expense (income), net	2,166	(1,257)	(289)
(Loss) income before income taxes	(80,595)	(77,077)	43,265
Income tax (benefit) expense	(6,833)	(6,416)	8,453
Income from equity method investment	(37)	(148)	(132)
Net (loss) income	$ (73,725)	$ (70,513)	$ 34,944
(Loss) earnings per common share:
Basic (USD per share)	$ (4.24)	$ (4.08)	$ 2.03
Diluted (USD per share)	$ (4.24)	$ (4.08)	$ 2.02
Weighted average common shares outstanding (shares)	17,379	17,271	17,204
Weighted average common shares and equivalents outstanding (shares)	17,379	17,271	17,330