PENSION AND OTHER POSTRETIREMENT BENEFITS (Schedule of Economic Assumptions and Impact of Change in Discount Rate on Benefit Obligation) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 26, 2021	Sep. 27, 2020	Dec. 27, 2020
Assumptions used to measure net pension and other postretirement cost
Increase in Discount Rate of 0.25% - Impact on defined benefit obligation for pension benefits	$ (10,344)
Decrease in Discount Rate of 0.25% - Impact on defined benefit obligation for pension benefits	$ 10,890
Pension Benefits
Assumptions used to measure benefit obligation at end of period
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	2.01%		1.83%
Assumptions used to measure net pension and other postretirement cost
Discount rate	1.87%	2.51%
Expected return on plan assets	3.53%	4.67%
Other Benefits
Assumptions used to measure benefit obligation at end of period
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	2.08%		1.80%
Assumptions used to measure net pension and other postretirement cost
Discount rate	1.80%	2.77%