Commitments and Contingencies (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 01, 2012 item
Pennsylvania
Commitments and Contingencies
Purchase obligations	$ 7.2
Area of property (in acres/square feet)	49
Industrial building
Commitments and Contingencies
Area of property (in acres/square feet)	500,000
Number of industrial buildings	2
Industrial building | Pennsylvania
Commitments and Contingencies
Purchase obligations	$ 1.6