Retirement And Benefit Plans (Components Of Net Periodic Pension And Other Postretirement Benefit Costs) (Details) (USD $) In Thousands	3 Months Ended		9 Months Ended
	Sep. 24, 2011	Sep. 25, 2010	Sep. 24, 2011	Sep. 25, 2010
Pension Benefits [Member]
Service cost	$ 636	$ 691	$ 1,909	$ 2,074
Interest cost	17,544	18,553	52,632	55,660
Expected return on plan assets	(19,264)	(20,873)	(59,467)	(62,620)
Recognized actuarial loss	4,309	3,310	13,062	9,929
Amortization of prior service costs and other				379
Net periodic benefit cost (income)	3,225	1,681	8,136	5,422
Other Benefits [Member]
Service cost	57	65	172	196
Interest cost	253	301	761	906
Recognized actuarial loss	55	56	165	168
Amortization of prior service costs and other	(1,002)	(1,001)	(3,007)	(3,004)
Net periodic benefit cost (income)	$ (637)	$ (579)	$ (1,909)	$ (1,734)