Pension Benefits (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 24, 2012	Jun. 26, 2011	Jun. 24, 2012	Jun. 26, 2011
Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]
Service cost	$ 213,000	$ 252,000	$ 430,000	$ 489,000
Interest cost	972,000	1,140,000	1,958,000	2,221,000
Expected return on plan assets	11,000	40,000	21,000	78,000
Amortization of actuarial loss	55,000	13,000	112,000	25,000
Amortization of transition obligation	15,000	33,000	29,000	65,000
Amortization of prior service costs	0	0	1,000	1,000
Net periodic pension cost	1,266,000	1,478,000	2,551,000	2,879,000
Estimated employer contributions	4,500,000		4,500,000
Pension contributions			$ 2,600,000