CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Income Statement [Abstract]
Net sales	$ 238,263	$ 201,944	$ 702,434	$ 591,911
Cost of sales	146,609	126,426	431,448	380,794
Gross margin	91,654	75,518	270,986	211,117
Selling, general and administrative expenses	47,886	50,230	135,258	132,254
Research and development expenses	7,531	7,085	22,195	22,185
Restructuring and impairment charges	1,007	9,413	3,260	9,413
Other operating (income) expense, net	1,431	(4)	3,536	(96)
Operating income	33,799	8,794	106,737	47,361
Equity income in unconsolidated joint ventures	1,773	937	5,884	3,177
Pension settlement charges	(534)	0	(534)	(55)
Other income (expense), net	(469)	1,446	3,738	1,294
Interest expense, net	(441)	(3,553)	(1,452)	(6,539)
Income before income tax expense	34,128	7,624	114,373	45,238
Income tax expense	8,999	618	29,371	10,453
Net income	$ 25,129	$ 7,006	$ 85,002	$ 34,785
Basic earnings per share (in dollars per share)	$ 1.34	$ 0.37	$ 4.54	$ 1.86
Diluted earnings per share (in dollars per share)	$ 1.33	$ 0.37	$ 4.51	$ 1.86
Shares used in computing:
Basic earnings per share (in shares)	18,740	18,688	18,727	18,678
Diluted earnings per share (in shares)	18,874	18,713	18,831	18,695