SIGNIFICANT ACCOUNTING POLICIES - Adopted Pronouncements (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 01, 2018	Jun. 25, 2017	Jul. 01, 2018	Jun. 25, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net cash provided by operating activities			$ 9,292	$ 15,766
Labor and Related Expense	$ 77,937	$ 86,823	157,149	178,231
Pension and Other Postretirement Benefit Expense	$ 2,779	$ 3,328	$ 5,557	6,655
2016-18
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net cash provided by operating activities				$ (1,000)