Consolidated Statements of Earnings - Unaudited - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Income Statement [Abstract]
Net sales	$ 118,021	$ 105,686	$ 231,551	$ 205,840
Cost of goods sold	76,208	69,892	151,305	135,822
Gross Margin	41,813	35,794	80,246	70,018
Selling, general and administrative expenses	19,621	15,808	36,993	31,056
Research and development expenses	6,476	6,049	12,983	12,052
Restructuring charges	1,172	729	2,367	1,507
Operating earnings	14,544	13,208	27,903	25,403
Other income (expense):
Interest expense	(571)	(752)	(1,112)	(1,436)
Interest income	472	298	954	551
Other income, net	(2,874)	1,170	(870)	1,631
Total other income	(2,973)	716	(1,028)	746
Earnings before income taxes	11,571	13,924	26,875	26,149
Income tax expense	4,362	3,958	8,118	7,699
Net earnings	$ 7,209	$ 9,966	$ 18,757	$ 18,450
Earnings per share:
Basic (in dollars per share)	$ 0.22	$ 0.30	$ 0.57	$ 0.56
Diluted (in dollars per share)	$ 0.21	$ 0.30	$ 0.56	$ 0.55
Basic weighted - average common shares outstanding (in shares):	33,051	32,890	33,014	32,846
Effect of dilutive securities (in shares)	513	461	513	493
Diluted weighted - average common shares outstanding (in shares)	33,564	33,351	33,527	33,339
Cash dividends declared per share (in dollars per share)	$ 0.04	$ 0.04	$ 0.08	$ 0.08