Employee Benefit Plans (Components Of Net Periodic Benefit Costs) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Apr. 01, 2012	Mar. 27, 2011
Defined Benefit Plan Disclosure [Line Items]
Curtailment loss	$ 200
Pension And SERPA Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	8,420	9,273
Interest cost	20,816	20,147
Expected return on plan assets	(29,277)	(26,653)
Prior service cost (credit)	740	745
Net loss	10,969	7,554
Curtailment loss		236
Net periodic benefit cost	11,668	11,302
Postretirement Healthcare Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	1,853	1,907
Interest cost	4,578	4,911
Expected return on plan assets	(2,356)	(2,346)
Prior service cost (credit)	(963)	(969)
Net loss	1,855	1,798
Net periodic benefit cost	$ 4,967	$ 5,301