Consolidated Statements of Earnings - Unaudited - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Income Statement [Abstract]
Net sales	$ 84,197	$ 120,684	$ 187,272	$ 238,308
Cost of goods sold	57,630	79,480	127,806	156,490
Gross margin	26,567	41,204	59,466	81,818
Selling, general and administrative expenses	14,668	17,036	31,427	34,597
Research and development expenses	5,522	6,257	12,930	13,048
Restructuring charges	135	911	375	2,995
Gain on sale of assets	0	(83)	0	(122)
Operating earnings	6,242	17,083	14,734	31,300
Other (expense) income:
Interest expense	(909)	(467)	(1,760)	(933)
Interest income	304	440	635	872
Other (expense) income, net	256	(1,107)	(1,726)	(1,010)
Total other (expense) income. net	(349)	(1,134)	(2,851)	(1,071)
Earnings before income taxes	5,893	15,949	11,883	30,229
Income tax expense	1,036	4,006	3,218	6,867
Net earnings	$ 4,857	$ 11,943	$ 8,665	$ 23,362
Earnings per share:
Basic (in dollars per share)	$ 0.15	$ 0.36	$ 0.27	$ 0.71
Diluted (in dollars per share)	$ 0.15	$ 0.36	$ 0.27	$ 0.70
Basic weighted - average common shares outstanding (in shares):	32,262	32,799	32,364	32,803
Effect of dilutive securities (in shares)	242	406	284	422
Diluted weighted - average common shares outstanding (in shares)	32,504	33,205	32,648	33,225
Cash dividends declared per share (in dollars per share)	$ 0.04	$ 0.04	$ 0.08	$ 0.08