CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Income Statement [Abstract]
Net sales	$ 198,810	$ 239,798
Cost of sales	133,180	154,404
Gross margin	65,630	85,394
Selling, General and Administrative Expense	40,330	43,252
Research and Development Expense	7,805	7,609
Restructuring and impairment charges	0	822
Other operating expense, net	20	911
Operating income	17,475	32,800
Equity income in unconsolidated joint ventures	1,218	837
Other (expense) income, net	(786)	1,404
Interest expense, net	(1,207)	(1,938)
Income before income tax expense	16,700	33,103
Income tax expense	3,441	4,704
Net income	$ 13,259	$ 28,399
Basic earnings per share (in dollars per share)	$ 0.71	$ 1.53
Diluted earnings per share (in dollars per share)	$ 0.71	$ 1.52
Shares used in computing:
Basic earnings per share (in shares)	18,669	18,557
Diluted earnings per share (in shares)	18,691	18,692