Consolidated Statements of Earnings (Loss) - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Net Sales
Net sales	$ 422,993	$ 396,679	$ 382,310
Cost of goods sold	282,562	256,251	255,201
Gross Margin	140,431	140,428	127,109
Selling, general and administrative expenses	71,943	61,624	59,586
Research and development expenses	25,146	24,040	22,461
Non-recurring environmental expense	0	0	14,541
Restructuring and impairment char	4,139	3,048	14,564
Gain (Loss) on Disposition of Property Plant Equipment	708	(11,450)	(2,156)
Operating earnings	38,495	63,166	18,113
Other (expense) income:
Interest expense	(3,343)	(3,702)	(2,628)
Interest income	1,284	1,305	3,073
Other income (expense)	3,817	(3,524)	(6,297)
Total other income (expense), net	1,758	(5,921)	(5,852)
Earnings before taxes	40,253	57,245	12,261
Income tax expense	25,805	22,865	5,307
Net earnings	$ 14,448	$ 34,380	$ 6,954
Basic
Net earnings (loss) per share (usd per share)	$ 0.44	$ 1.05	$ 0.21
Diluted
Diluted net earnings (loss) per share (usd per share)	$ 0.43	$ 1.03	$ 0.21
Basic weighted-average common shares outstanding (in shares)	32,892	32,728	32,959
Effect of dilutive securities (in shares)	528	523	525
Diluted weighted - average common shares outstanding (in shares)	33,420	33,251	33,484
Cash dividends declared per share (in dollars per share)	$ 0.16	$ 0.16	$ 0.160