Property, Plant and Equipment (Details) (USD $)	3 Months Ended
	Mar. 31, 2013	Mar. 25, 2012	Dec. 30, 2012
Property, Plant and Equipment [Line Items]
Land and buildings	$ 73,114,000		$ 70,235,000
Machinery and equipment	422,568,000		408,620,000
Leasehold improvements and others	8,435,000		8,374,000
Construction in progress	10,336,000		7,565,000
Property, plant and equipment, gross	514,453,000		494,794,000
Accumulated depreciation	(361,197,000)		(347,250,000)
Property, plant and equipment, net	153,256,000		147,544,000
Depreciation expense	$ 7,000,000	$ 6,600,000