CONDENSED CONSOLIDATED STATEMENTS OF EARNINGS/(LOSS) - UNAUDITED (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 29, 2013	Sep. 30, 2012	Sep. 29, 2013	Sep. 30, 2012
Income Statement [Abstract]
Net Sales	$ 159,563	$ 137,357	$ 460,636	$ 438,620
Costs and expenses:
Cost of goods sold	122,034	110,763	356,438	364,039
Insurance recovery for business interruption - casualties		(4,192)		(15,242)
Selling, general and administrative expenses	20,765	19,387	62,921	58,169
Research and development expenses	5,718	4,350	17,741	15,590
Insurance recovery for property damage - Casualties				(1,769)
Restructuring and impairment charge - Note M	953	245	8,755	3,384
Operating earnings	10,093	6,804	14,781	14,449
Other (expense)/income:
Interest expense	(849)	(584)	(2,843)	(1,869)
Interest income	442	425	1,301	1,341
Other	706	763	694	297
Total other income/(expense)	299	604	(848)	(231)
Earnings before income taxes	10,392	7,408	13,933	14,218
Income tax expense	3,573	1,491	14,881	2,717
Net earnings/(loss)	$ 6,819	$ 5,917	$ (948)	$ 11,501
Net earnings/(loss) per share - Note J
Basic	$ 0.20	$ 0.17	$ (0.03)	$ 0.34
Diluted	$ 0.20	$ 0.17	$ (0.03)	$ 0.33
Cash dividends declared per share	$ 0.035	$ 0.035	$ 0.105	$ 0.105
Average common shares outstanding:
Basic	33,696	33,923	33,603	34,017
Diluted	34,331	34,471	33,603	34,588