Pension Benefits (Details) (USD $)	3 Months Ended			6 Months Ended
	Jun. 30, 2013	Jun. 24, 2012	Mar. 25, 2012	Jun. 30, 2013
Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]
Service cost	$ 267,000	$ 213,000	$ 430,000	$ 535,000
Interest cost	869,000	972,000	1,958,000	1,748,000
Expected return on plan assets	25,000	11,000	21,000	51,000
Amortization of actuarial loss	386,000	55,000	112,000	775,000
Amortization of transition obligation	0	15,000	29,000	0
Amortization of prior service costs	0	0	1,000	1,000
Net periodic pension cost	1,547,000	1,266,000	2,551,000	3,110,000
Estimated employer contributions	5,100,000			5,100,000
Pension contributions				$ 2,800,000