PENSION AND OTHER POSTRETIREMENT BENEFITS (Schedule of Plan Asset Allocations) (Details) - Pension Benefits	Dec. 27, 2020	Dec. 29, 2019
Defined Benefit Plan Disclosure [Line Items]
Total assets	100.00%	100.00%
Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Total assets	1.00%	4.00%
Union plan | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Total assets	2.00%	2.00%
Union plan | Fixed income funds
Defined Benefit Plan Disclosure [Line Items]
Total assets	2.00%	2.00%
GK Pension Plan | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Total assets	20.00%	20.00%
GK Pension Plan | Fixed income funds
Defined Benefit Plan Disclosure [Line Items]
Total assets	13.00%	12.00%
GK Pension Plan | Real estate
Defined Benefit Plan Disclosure [Line Items]
Total assets	1.00%	2.00%
U.K. Plans | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Total assets	35.00%	40.00%
U.K. Plans | Fixed income funds
Defined Benefit Plan Disclosure [Line Items]
Total assets	20.00%	18.00%
U.K. Plans | Real estate
Defined Benefit Plan Disclosure [Line Items]
Total assets	6.00%	0.00%