STOCKHOLDERS' EQUITY (Schedule of Changes in Accumulated Other Comprehensive Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 26, 2016	Jun. 28, 2015	Jun. 26, 2016	Jun. 28, 2015
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance			$ 1,261,810	$ 2,196,801
Amounts reclassified from accumulated other comprehensive loss to net income			(127)	159
Total other comprehensive income (loss), net of tax	$ (1,941)	$ 8,791	(8,796)	6,703
Balance	818,693	1,159,953	818,693	1,159,953
Accumulated Other Comprehensive Loss [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance			(58,930)	(62,541)
Other comprehensive income (loss) before reclassifications			(8,669)	6,544
Amounts reclassified from accumulated other comprehensive loss to net income			(127)	159
Total other comprehensive income (loss), net of tax			(8,796)	6,703
Balance	(67,726)	(55,838)	(67,726)	(55,838)
Losses Related to Pension and Other Postretirement Benefits [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance			(58,997)	(62,572)
Other comprehensive income (loss) before reclassifications			(8,934)	6,501
Amounts reclassified from accumulated other comprehensive loss to net income			205	222
Total other comprehensive income (loss), net of tax			(8,729)	6,723
Balance	(67,726)	(55,849)	(67,726)	(55,849)
Unrealized Holding Gains on Available-for-Sale Securities [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance			67	31
Other comprehensive income (loss) before reclassifications			265	43
Amounts reclassified from accumulated other comprehensive loss to net income			(332)	(63)
Total other comprehensive income (loss), net of tax			(67)	(20)
Balance	$ 0	$ 11	$ 0	$ 11