Acquisition (Details 1) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jul. 01, 2012	Jun. 30, 2013	Jul. 01, 2012
Summary of net sales and earnings before income taxes
Net sales	$ 151,561	$ 154,294	$ 301,073	$ 301,263
Earnings before income taxes	783	4,513	3,541	6,810
D and R Technology [Member]
Summary of net sales and earnings before income taxes
Net sales	13,194		25,896
Earnings before income taxes	$ 1,706		$ 1,856