Employee Benefit Plans (Schedule Of Assumptions Used To Determine Net Periodic Benefit Cost) (Details) (USD $) In Thousands	3 Months Ended		9 Months Ended
	Sep. 25, 2011	Sep. 26, 2010	Sep. 25, 2011	Sep. 26, 2010
Defined Benefit Plan Disclosure [Line Items]
Curtailment loss				$ 27,100
Pension And SERPA Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	9,274	10,345	27,819	31,131
Interest cost	20,147	19,409	60,441	58,323
Expected return on plan assets	(26,652)	(24,392)	(79,959)	(73,080)
Prior service cost (credit)	746	1,085	2,235	3,351
Net loss	7,550	5,594	22,659	16,878
Curtailment loss		15,505	236	15,505
Settlement loss		476		3,058
Net periodic benefit cost	11,065	28,022	33,431	55,166
Postretirement Healthcare Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	1,907	2,480	5,721	7,514
Interest cost	4,911	5,297	14,733	15,891
Expected return on plan assets	(2,346)	(2,445)	(7,038)	(7,335)
Prior service cost (credit)	(969)	(629)	(2,907)	(1,887)
Net loss	1,798	2,251	5,394	6,753
Curtailment loss		12,666		11,643
Net periodic benefit cost	$ 5,301	$ 19,620	$ 15,903	$ 32,579