Business Segments (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 25, 2012	Dec. 30, 2012
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	$ 206,441	$ 202,457
Property, plant and equipment, net	153,256		147,544
UNITED STATES
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	76,883	81,656
Property, plant and equipment, net	55,253		52,458
MEXICO
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	129,558	120,801
Property, plant and equipment, net	$ 98,003		$ 95,086