Employee Benefits (Details) (USD $)	3 Months Ended		9 Months Ended
	Oct. 01, 2011	Sep. 25, 2010	Oct. 01, 2011	Sep. 25, 2010
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Anticipated full year pension plan contribution	$ 1,500,000		$ 1,500,000
Pension plan contributions			1,200,000
Pension benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	230,000	149,000	691,000	447,000
Interest cost	2,343,000	2,206,000	7,028,000	6,617,000
Expected return on plan assets	(2,786,000)	(2,706,000)	(8,357,000)	(8,119,000)
Amortization of prior service cost	1,000	74,000	2,000	221,000
Amortization of net (gain) loss	587,000	452,000	1,760,000	1,357,000
Net periodic benefit cost	375,000	175,000	1,124,000	523,000
Other benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	75,000	68,000	226,000	202,000
Interest cost	309,000	318,000	928,000	953,000
Amortization of prior service cost	(1,000)	1,000	(2,000)	2,000
Amortization of net (gain) loss	(2,000)	39,000	(8,000)	117,000
Net periodic benefit cost	$ 381,000	$ 426,000	$ 1,144,000	$ 1,274,000