Consolidated Statements of Earnings - Unaudited - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 27, 2015	Sep. 30, 2016	Sep. 27, 2015
Income Statement [Abstract]
Net sales	$ 99,697	$ 90,646	$ 295,095	$ 289,028
Cost of goods sold	63,056	59,200	190,528	192,073
Gross Margin	36,641	31,446	104,567	96,955
Selling, general and administrative expenses	16,048	12,689	46,459	43,623
Research and development expenses	6,284	5,692	18,414	16,378
Environmental Remediation Expense	0	14,541	0	14,541
Restructuring and impairment charges	1,969	2,373	2,175	5,229
Gain (Loss) on Disposition of Property Plant Equipment	150	(1)	11,501	(2)
Operating earnings (loss)	12,490	(3,850)	49,020	17,182
Other (expense) income:
Interest expense	(917)	(714)	(2,746)	(1,955)
Interest income	203	713	1,082	2,354
Other expense	(46)	(3,072)	(1,482)	(4,641)
Total other expense	(760)	(3,073)	(3,146)	(4,242)
Earnings (loss) before income taxes	11,730	(6,923)	45,874	12,940
Income tax expense (benefit)	8,010	(2,163)	19,804	(7,667)
Net earnings (loss)	$ 3,720	$ (4,760)	$ 26,070	$ 20,607
Earnings (loss) per share:
Basic (in dollars per share)	$ 0.11	$ (0.15)	$ 0.80	$ 0.62
Diluted (in dollars per share)	$ 0.11	$ (0.15)	$ 0.79	$ 0.61
Basic weighted - average common shares outstanding (in shares):	32,759	32,770	32,716	33,083
Effect of dilutive securities (in shares)	495	0	494	485
Diluted weighted - average common shares outstanding (in shares)	33,254	32,770	33,210	33,568
Cash dividends declared per share (in dollars per share)	$ 0.04	$ 0.04	$ 0.12	$ 0.12