CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Income Statement [Abstract]
Net sales	$ 227,099	$ 200,527
Cost of sales	178,550	161,959
Gross profit	48,549	38,568
Selling, product development and administrative expenses	35,633	33,027
Impairment of goodwill and other long-lived assets	0	61,109
Restructuring expenses	777	0
Operating income (loss)	12,139	(55,568)
(Gain) loss on the sale of a business	698	0
Employee benefit plans settlement expenses	0	385
Interest expense	3,448	2,857
Other (income) expense, net	86	(418)
Income (loss) before income taxes	7,907	(58,392)
Income tax expense (benefit)	2,821	(2,015)
(Income) loss from equity method investment	(8)	44
Net income (loss)	$ 5,094	$ (56,421)
Earnings (loss) per share:
Basic (USD per share)	$ 0.29	$ (3.25)
Diluted (USD per share)	$ 0.28	$ (3.25)
Weighted average number of common shares outstanding:
Basic (shares)	17,545	17,336
Diluted (shares)	17,888	17,336