CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Income Statement [Abstract]
Net sales	$ 100,135	$ 67,313
Cost of products sold	63,730	44,560
Gross profit	36,405	22,753
Costs and expenses:
General and administrative expenses	9,168	8,177
Selling and distribution expenses	6,309	5,212
Amortization of purchased intangible assets	398	805
Restructuring expenses	78	144
Anti-dumping duty penalties	0	3,103
Total costs and expenses	15,953	17,441
Operating income	20,452	5,312
Other expense:
Other expense, net	(21)	(377)
Interest expense, net	(373)	(465)
Income before income taxes	20,058	4,470
Income tax provision	4,888	550
Net income	$ 15,170	$ 3,920
Net income per share
Basic (in dollars per share)	$ 1.02	$ 0.26
Diluted (in dollars per share)	$ 1.01	$ 0.26
Weighted-average shares outstanding:
Basic (in shares)	14,606,052	14,449,915
Diluted (in shares)	14,671,689	14,449,915
Dividends declared per common share (in dollars per share)	$ 0.02	$ 0.02