Employee Benefit Plans (Components Of Net Periodic Benefit Costs) (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 27, 2015	Sep. 28, 2014	Sep. 27, 2015	Sep. 28, 2014
Pension Plans and Supplemental Employee Retirement Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 10,010	$ 7,874	$ 30,030	$ 23,623
Interest cost	21,836	21,731	65,508	65,193
Expected return on plan assets	(36,232)	(34,184)	(108,696)	(102,551)
Prior service cost	109	279	327	838
Net loss	13,678	9,141	41,031	27,422
Net periodic benefit cost	9,401	4,841	28,200	14,525
Postretirement Healthcare Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	2,065	1,754	6,195	5,262
Interest cost	3,541	4,220	10,623	12,659
Expected return on plan assets	(2,877)	(2,607)	(8,631)	(7,822)
Prior service cost	(804)	(963)	(2,412)	(2,890)
Net loss	993	1,182	2,979	3,546
Net periodic benefit cost	$ 2,918	$ 3,586	$ 8,754	$ 10,755