PENSION AND OTHER POSTRETIREMENT BENEFITS (Schedule of Net Defined Benefit Pension and Other Postretirement Costs) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 26, 2017	Mar. 27, 2016
Pension Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Interest cost	$ 1,393	$ 1,396
Estimated return on plan assets	(1,313)	(1,314)
Amortization of net loss	233	165
Net costs	313	247
Other Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Interest cost	13	12
Estimated return on plan assets	0	0
Amortization of net loss	0	0
Net costs	$ 13	$ 12