Consolidated Statements of Earnings - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Statement [Abstract]
Net sales	$ 424,066	$ 468,999	$ 470,483
Cost of goods sold	285,003	311,424	305,510
Gross margin	139,063	157,575	164,973
Selling, general and administrative expenses	67,787	70,408	73,569
Research and development expenses	24,317	25,967	25,304
Restructuring charges	1,830	7,448	5,062
Gain on sale of assets	0	(63)	0
Operating earnings	45,129	53,815	61,038
Other (expense) income:
Interest expense	(3,272)	(2,648)	(2,085)
Interest income	1,047	1,737	1,826
Other income (expense)	2,575	(2,638)	(2,676)
Total other income (expense), net	350	(3,549)	(2,935)
Earnings before taxes	45,479	50,266	58,103
Income tax expense	10,793	14,120	11,571
Net earnings	$ 34,686	$ 36,146	$ 46,532
Net earnings per share:
Basic	$ 1.07	$ 1.11	$ 1.41
Diluted	$ 1.06	$ 1.09	$ 1.39
Basic weighted-average common shares outstanding	32,317	32,700	33,024
Effect of dilutive securities	267	405	545
Diluted weighted-average common shares outstanding	32,584	33,105	33,569
Cash dividends declared per share	$ 0.16	$ 0.16	$ 0.16