CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Statement [Abstract]
Net sales	$ 397,550	$ 326,429	$ 192,803
Cost of products sold	252,627	215,734	133,412
Gross profit	144,923	110,695	59,391
Costs and expenses:
General and administrative expenses	37,976	38,452	27,135
Selling and distribution expenses	27,475	22,761	18,589
Amortization of purchased intangible assets	1,544	2,944	4,060
Restructuring expenses, net and asset impairments	19,503	1,114	4,283
Anti-dumping duty penalties	0	8,000	0
Goodwill impairment charge	0	0	17,584
Total costs and expenses	86,498	73,271	71,651
Operating income (loss)	58,425	37,424	(12,260)
Other expense:
Other expense, net	(169)	(1,202)	(1,376)
Interest expense, net	(1,554)	(1,615)	(1,648)
Income (loss) before income taxes	56,702	34,607	(15,284)
Income tax provision	22,661	4,134	3,569
Net income (loss)	$ 34,041	$ 30,473	$ (18,853)
Net income (loss) per share:
Basic (in dollars per share)	$ 2.29	$ 2.05	$ (1.31)
Diluted (in dollars per share)	$ 2.28	$ 2.04	$ (1.31)
Weighted-average shares outstanding:
Basic (in shares)	14,579,608	14,529,745	14,346,851
Diluted (in shares)	14,655,350	14,620,635	14,346,851
Dividends declared per common share (in dollars per share)	$ 0.29	$ 0.08	$ 0.08