SIGNIFICANT ACCOUNTING POLICIES - AOCI (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 26, 2017	Mar. 27, 2016
Changes in accumulated other comprehensive loss
Balance at the beginning of the period	$ (461,515)
Other comprehensive income (loss) before reclassifications	72
Amounts reclassified from AOCL	2,571
Other comprehensive income	2,643	$ 1,807
Balance at the end of the period	(458,872)
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Retirement benefit expense	3,327	3,694
Benefit for income taxes	(55,449)	(10,115)
Net of tax	95,575	12,741
Minimum Pension and Post-Retirement Liability
Changes in accumulated other comprehensive loss
Balance at the beginning of the period	(450,506)
Amounts reclassified from AOCL	2,571
Other comprehensive income	2,571
Balance at the end of the period	(447,935)
Minimum Pension and Post-Retirement Liability | Amount Reclassified from AOCI
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Retirement benefit expense	4,285	3,837
Benefit for income taxes	(1,714)	(1,535)
Net of tax	2,571	$ 2,302
Other Comprehensive Loss Related to Equity Investments
Changes in accumulated other comprehensive loss
Balance at the beginning of the period	(11,009)
Other comprehensive income (loss) before reclassifications	72
Other comprehensive income	72
Balance at the end of the period	$ (10,937)