Retirement And Benefit Plans (Components Of Net Periodic Pension And Other Postretirement Benefit Costs (Income)) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 26, 2011
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 943	$ 639
Interest cost	16,158	17,542
Expected return on plan assets	(20,773)	(20,105)
Recognized actuarial loss	4,491	4,427
Net periodic benefit cost (income)	819	2,503
Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	73	96
Interest cost	235	301
Recognized actuarial loss	55	84
Amortization of prior service credits	(1,002)	(1,002)
Net periodic benefit cost (income)	$ (639)	$ (521)