Property, Plant and Equipment (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 24, 2012	Jun. 26, 2011	Jun. 24, 2012	Jun. 26, 2011	Dec. 25, 2011
Property, Plant and Equipment [Line Items]
Land and buildings	$ 67,988,000		$ 67,988,000		$ 67,500,000
Machinery and equipment	397,451,000		397,451,000		390,304,000
Leasehold improvements and others	8,309,000		8,309,000		8,274,000
Construction in progress	8,413,000		8,413,000		8,908,000
Property, plant and equipment, gross	482,161,000		482,161,000		474,986,000
Accumulated depreciation	(339,924,000)		(339,924,000)		(329,239,000)
Property, plant and equipment, net	142,237,000		142,237,000		145,747,000
Depreciation expense	$ 6,300,000	$ 7,200,000	$ 12,900,000	$ 14,200,000