SIGNIFICANT ACCOUNTING POLICIES - AOCI (Details) - USD ($) $ in Thousands	3 Months Ended
	Apr. 01, 2018	Mar. 26, 2017
Changes in stockholders' equity
Balance at the beginning of the period	$ (449,369)
Amounts reclassified from AOCL	5,550
Other comprehensive income	5,550	$ 2,643
Balance at the end of the period	(443,819)
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Retirement benefit expense	2,778	3,327
Benefit for income taxes	7,872	(55,449)
Net of tax	38,941	95,575
Minimum Pension and Post-Retirement Liability
Changes in stockholders' equity
Balance at the beginning of the period	(442,406)
Amounts reclassified from AOCL	5,550
Other comprehensive income	5,550
Balance at the end of the period	(436,856)
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	5,550	4,285
Benefit for income taxes		(1,714)
Net of tax	5,550	$ 2,571
Other Comprehensive Loss Related to Equity Investments
Changes in stockholders' equity
Balance at the beginning of the period	(6,963)
Balance at the end of the period	$ (6,963)