Consolidated Statements of Earnings - Unaudited - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Income Statement [Abstract]
Net sales	$ 106,243	$ 99,697	$ 312,083	$ 295,095
Cost of goods sold	68,705	63,056	204,527	190,528
Gross Margin	37,538	36,641	107,556	104,567
Selling, general and administrative expenses	15,915	16,048	46,970	46,459
Research and development expenses	6,380	6,284	18,432	18,414
Restructuring charges	1,435	1,969	2,942	2,175
Gain (Loss) on Disposition of Property Plant Equipment	(697)	150	(698)	11,501
Operating earnings	13,111	12,490	38,514	49,020
Other income (expense):
Interest expense	(773)	(917)	(2,209)	(2,746)
Interest income	363	203	914	1,082
Other income (expense)	1,258	(46)	2,889	(1,482)
Total other income (expense)	848	(760)	1,594	(3,146)
Earnings before income taxes	13,959	11,730	40,108	45,874
Income tax expense	4,340	8,010	12,039	19,804
Net earnings	$ 9,619	$ 3,720	$ 28,069	$ 26,070
Earnings per share:
Basic (in dollars per share)	$ 0.29	$ 0.11	$ 0.85	$ 0.80
Diluted (in dollars per share)	$ 0.29	$ 0.11	$ 0.84	$ 0.79
Basic weighted - average common shares outstanding (in shares):	32,935	32,759	32,876	32,716
Effect of dilutive securities (in shares)	456	495	475	494
Diluted weighted - average common shares outstanding (in shares)	33,391	33,254	33,351	33,210
Cash dividends declared per share (in dollars per share)	$ 0.04	$ 0.04	$ 0.12	$ 0.12