CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Income Statement [Abstract]
Net sales	$ 221,744	$ 146,160	$ 448,843	$ 346,687
Cost of sales	173,958	117,742	352,508	279,701
Gross profit	47,786	28,418	96,335	66,986
Selling, product development and administrative expenses	38,182	30,164	73,815	63,191
Impairment of goodwill and other long-lived assets	0	0	0	61,109
Restructuring expenses	190	0	967	0
Operating income (loss)	9,414	(1,746)	21,553	(57,314)
(Gain) loss on the sale of a business	266	0	964	0
Employee benefit plans settlement expenses	0	0	0	385
Interest expense	2,414	4,476	5,862	7,333
Other (income) expense, net	206	248	292	(170)
Income (loss) before income taxes	6,528	(6,470)	14,435	(64,862)
Income tax expense (benefit)	905	(595)	3,726	(2,610)
(Income) loss from equity method investment	(157)	(18)	(165)	26
Net income (loss)	$ 5,780	$ (5,857)	$ 10,874	$ (62,278)
Earnings (loss) per share:
Basic (in usd per share)	$ 0.33	$ (0.34)	$ 0.62	$ (3.59)
Diluted (in usd per share)	$ 0.32	$ (0.34)	$ 0.61	$ (3.59)
Weighted average number of common shares outstanding:
Basic (in shares)	17,575	17,372	17,560	17,354
Diluted (in shares)	17,977	17,372	17,923	17,354