STOCKHOLDERS' EQUITY (Schedule of Changes in Accumulated Other Comprehensive Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 25, 2016	Sep. 27, 2015	Sep. 25, 2016	Sep. 27, 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			(25)	251
Total other comprehensive income (loss), net of tax	$ 1,878	$ (10,164)	(6,918)	(3,461)
Balance	916,807	1,242,668	916,807	1,242,668
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			(6,893)	(3,712)
Amounts reclassified from accumulated other comprehensive loss to net income			(25)	251
Total other comprehensive income (loss), net of tax			(6,918)	(3,461)
Balance	(65,848)	(66,002)	(65,848)	(66,002)
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			(7,158)	(3,845)
Amounts reclassified from accumulated other comprehensive loss to net income			307	334
Total other comprehensive income (loss), net of tax			(6,851)	(3,511)
Balance	(65,848)	(66,083)	(65,848)	(66,083)
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	133
Amounts reclassified from accumulated other comprehensive loss to net income			(332)	(83)
Total other comprehensive income (loss), net of tax			(67)	50
Balance	$ 0	$ 81	$ 0	$ 81