Consolidated Statements of Earnings - Unaudited - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Income Statement [Abstract]
Net sales	$ 105,686	$ 98,693	$ 205,840	$ 195,398
Cost of goods sold	69,892	64,236	135,822	127,472
Gross Margin	35,794	34,457	70,018	67,926
Selling, general and administrative expenses	15,809	15,764	31,055	30,411
Research and development expenses	6,049	5,967	12,052	12,130
Restructuring charges	729	206	1,507	206
Gain (Loss) on Disposition of Property Plant Equipment	1	11,577	(1)	11,351
Operating earnings	13,208	24,097	25,403	36,530
Other income (expense):
Interest expense	(752)	(1,009)	(1,436)	(1,829)
Interest income	298	331	551	879
Other income (expense)	1,170	(1,240)	1,631	(1,436)
Total other income (expense)	716	(1,918)	746	(2,386)
Earnings before income taxes	13,924	22,179	26,149	34,144
Income tax expense	3,958	7,692	7,699	11,794
Net earnings	$ 9,966	$ 14,487	$ 18,450	$ 22,350
Earnings per share:
Basic (in dollars per share)	$ 0.30	$ 0.44	$ 0.56	$ 0.68
Diluted (in dollars per share)	$ 0.30	$ 0.44	$ 0.55	$ 0.67
Basic weighted - average common shares outstanding (in shares):	32,890	32,759	32,846	32,695
Effect of dilutive securities (in shares)	461	466	493	485
Diluted weighted - average common shares outstanding (in shares)	33,351	33,225	33,339	33,180
Cash dividends declared per share (in dollars per share)	$ 0.04	$ 0.04	$ 0.08	$ 0.08