Pension And Other Postretirement Benefits (Net Benefit Cost Of Pension And Postretirement Benefit Plans) (Details) (USD $) In Thousands	3 Months Ended		6 Months Ended
	Jun. 26, 2011	Jun. 27, 2010	Jun. 26, 2011	Jun. 27, 2010
Pension Benefit Plan [Member]
Service cost	$ 613	$ 627	$ 1,192	$ 1,257
Interest cost	4,342	4,275	8,586	8,578
Expected return on Plan assets	(4,943)	(4,003)	(9,843)	(8,016)
Net amortization and deferral	976	995	2,031	1,999
Net benefit cost	988	1,894	1,966	3,818
Other Postretirement Benefit [Member]
Service cost	198	190	396	380
Interest cost	549	653	1,100	1,305
Expected return on Plan assets
Net amortization and deferral	69	131	138	262
Net benefit cost	$ 816	$ 974	$ 1,634	$ 1,947