Derivative Instruments and Hedging Activities (Details) (Commodity contracts [Member], Designated as Hedging Instrument [Member], USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 25, 2010
Other Current Assets [Member]
Derivatives, Fair Value [Line Items]
Other current assets: gain positions	$ 85	$ 891
Other current assets: loss positions	(25)
Other Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Other current liability: gain positions	339
Other current liability: loss positions	$ (1,078)