PENSION AND OTHER POSTRETIREMENT BENEFITS (Schedule of Net Periodic Benefit Cost (Income)) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 25, 2016	Dec. 27, 2015	Dec. 28, 2014
Pension Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Interest cost	$ 5,585	$ 7,754	$ 8,103
Estimated return on plan assets	(5,256)	(6,684)	(6,373)
Settlement loss (gain)	2,064	3,843	93
Amortization of net loss (gain)	659	714	56
Net cost	3,052	5,627	1,879
Other Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Interest cost	51	67	81
Estimated return on plan assets	0	0	0
Settlement loss (gain)	(2)	(4)	(9)
Amortization of net loss (gain)	0	0	0
Net cost	$ 49	$ 63	$ 72