PENSION AND OTHER POSTRETIREMENT BENEFITS (Schedule of Economic Assumptions, and Impact of Change in Discount Rate on Benefit Obligation) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 25, 2016	Dec. 27, 2015
Net pension and other postretirement cost:
Increase in Discount Rate of 0.25% - impact on defined benefit obligation for pension benefits	$ (5,087)
Decrease in Discount Rate of 0.25% - impact on defined benefit obligation for pension benefits	$ 4,828
Pension Benefits
Benefit obligation:
Discount rate	3.69%	4.31%	4.47%
Net pension and other postretirement cost:
Discount rate	4.32%	4.47%	4.22%
Expected return on plan assets	5.50%	5.50%	5.50%
Other Benefits
Benefit obligation:
Discount rate	3.39%	3.81%	4.47%
Net pension and other postretirement cost:
Discount rate	3.81%	4.47%	4.22%