PROPERTY, PLANT AND EQUIPMENT (Details) - USD ($) $ in Thousands	Dec. 26, 2020	Dec. 28, 2019
Long-lived assets
Property, plant and equipment, at cost	$ 1,341,380	$ 1,245,261
Land and improvements
Long-lived assets
Property, plant and equipment, at cost	114,831	111,091
Buildings and improvements
Long-lived assets
Property, plant and equipment, at cost	373,271	364,396
Machinery and equipment
Long-lived assets
Property, plant and equipment, at cost	616,765	584,447
Transportation equipment
Long-lived assets
Property, plant and equipment, at cost	28,610	23,650
Office furniture and equipment
Long-lived assets
Property, plant and equipment, at cost	101,487	85,130
Construction in progress
Long-lived assets
Property, plant and equipment, at cost	$ 106,416	$ 76,547