CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Income Statement [Abstract]
Net sales	$ 146,160	$ 220,811	$ 346,687	$ 438,836
Cost of sales	117,742	175,536	279,701	351,505
Gross profit	28,418	45,275	66,986	87,331
Selling, product development and administrative expenses	30,164	32,096	63,191	65,102
Impairment of goodwill and other long-lived assets	0	0	61,109	0
Operating (loss) income	(1,746)	13,179	(57,314)	22,229
Employee benefit plans settlement expenses	0	25,515	385	25,515
Interest expense	4,476	3,731	7,333	7,359
Other expense (income), net	248	(873)	(170)	(474)
Loss before income taxes	(6,470)	(15,194)	(64,862)	(10,171)
Income tax benefit	(595)	(8,199)	(2,610)	(7,093)
(Income) loss from equity method investment	(18)	(49)	26	(22)
Net loss	$ (5,857)	$ (6,946)	$ (62,278)	$ (3,056)
Loss per share:
Basic (USD per share)	$ (0.34)	$ (0.40)	$ (3.59)	$ (0.18)
Diluted (USD per share)	$ (0.34)	$ (0.40)	$ (3.59)	$ (0.18)
Weighted average number of common shares outstanding:
Basic (shares)	17,372	17,267	17,354	17,260
Diluted (shares)	17,372	17,267	17,354	17,260