Pension and Postretirement Benefits (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jul. 01, 2012	Jun. 26, 2011	Jul. 01, 2012	Jun. 26, 2011
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Contributions to defined benefit pension plans			$ 3,500
Expected contributions during the remainder of fiscal year	2,300		2,300
Pension [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	1,081	1,090	2,279	2,169
Interest cost	5,052	5,231	10,546	10,454
Expected return on assets	(5,232)	(6,258)	(10,903)	(12,507)
Net amortization and deferrals	1,761	1,295	3,669	2,590
Net periodic benefit cost	2,662	1,358	5,591	2,706
Postretirement [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	184	171	368	342
Interest cost	440	440	880	880
Expected return on assets	0	0	0	0
Net amortization and deferrals	20	18	40	36
Net periodic benefit cost	$ 644	$ 629	$ 1,288	$ 1,258