PENSION AND OTHER POSTRETIREMENT BENEFITS (Schedule of Net Periodic Benefit Cost (Income)) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 27, 2015	Dec. 28, 2014	Dec. 29, 2013
Pension Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Service cost	$ 0	$ 0	$ 0
Interest cost	7,754	8,103	7,954
Estimated return on plan assets	(6,684)	(6,373)	(5,393)
Settlement loss (gain)	3,843	93	0
Amortization of net loss (gain)	714	56	1,001
Net cost	5,627	1,879	3,562
Other Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Service cost	0	0	0
Interest cost	67	81	78
Estimated return on plan assets	0	0	0
Settlement loss (gain)	(4)	(9)	(15)
Amortization of net loss (gain)	0	0	0
Net cost	$ 63	$ 72	$ 63