Employee Benefit Plans (Components Of Net Periodic Benefit Costs) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jul. 01, 2012	Jun. 26, 2011	Jul. 01, 2012	Jun. 26, 2011
Pension And SERPA Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 8,420	$ 9,273	$ 16,840	$ 18,545
Interest cost	20,816	20,147	41,632	40,294
Expected return on plan assets	(29,277)	(26,653)	(58,555)	(53,307)
Prior service cost	740	745	1,479	1,489
Net loss	10,969	7,554	21,937	15,109
Curtailment loss				236
Net periodic benefit cost	11,668	11,066	23,333	22,366
Postretirement Healthcare Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	1,853	1,907	3,706	3,814
Interest cost	4,578	4,911	9,155	9,822
Expected return on plan assets	(2,356)	(2,346)	(4,712)	(4,692)
Prior service cost	(963)	(969)	(1,927)	(1,938)
Net loss	1,855	1,798	3,711	3,596
Net periodic benefit cost	$ 4,967	$ 5,301	$ 9,933	$ 10,602