Derivative Financial Instruments (Details 2) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jul. 02, 2011	Jun. 30, 2012	Jul. 02, 2011
Derivative Instruments, Gain (Loss)
Reclassification of interest rate swap losses included in accumulated other comprehensive loss into earnings in the next nine months	$ 1,300,000		$ 1,300,000
Minimum unencumbered cash and highly rated short-term investments required to be maintained all times under interest rate swap agreement	150,000,000		150,000,000
Cash flow hedges | Interest rate swap
Derivative Instruments, Gain (Loss)
Loss Recognized in OCI on Derivatives (Effective Portion) during period	(6,000)	(405,000)	(138,000)	(427,000)
Loss Reclassified from Accumulated OCI into Income (Effective Portion), included in rent expense during period	$ (447,000)	$ (473,000)	$ (880,000)	$ (1,297,000)