CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Statement [Abstract]
Net sales	$ 100,094	$ 87,883	$ 311,183	$ 236,111
Cost of products sold	63,870	58,155	196,481	156,855
Gross profit	36,224	29,728	114,702	79,256
Costs and expenses:
General and administrative expenses	10,128	9,630	28,756	27,550
Selling and distribution expenses	6,983	5,420	20,531	16,427
Amortization of purchased intangible assets	394	769	1,189	2,365
Restructuring expenses, net and asset impairments	5,898	192	6,300	553
Anti-dumping duty penalties	0	4,897	0	8,000
Total costs and expenses	23,403	20,908	56,776	54,895
Operating income	12,821	8,820	57,926	24,361
Other income (expense):
Other income (expense), net	170	(335)	492	(1,039)
Interest expense, net	(387)	(495)	(1,169)	(1,096)
Income before income taxes	12,604	7,990	57,249	22,226
Income tax provision	5,689	3,080	17,920	7,024
Net income	$ 6,915	$ 4,910	$ 39,329	$ 15,202
Net income per share
Basic (in dollars per share)	$ 0.47	$ 0.33	$ 2.67	$ 1.02
Diluted (in dollars per share)	$ 0.46	$ 0.33	$ 2.64	$ 1.02
Weighted-average shares outstanding:
Basic (in shares)	14,632,276	14,571,155	14,589,655	14,518,765
Diluted (in shares)	14,851,166	14,571,155	14,800,132	14,518,765
Dividends declared per common share (in dollars per share)	$ 0.125	$ 0.02	$ 0.165	$ 0.06