PROPERTY, PLANT AND EQUIPMENT (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 26, 2015
Long-lived assets
Property, plant and equipment, at cost	$ 1,105,736	$ 1,081,056
Land and improvements
Long-lived assets
Property, plant and equipment, at cost	85,724	79,450
Buildings and improvements
Long-lived assets
Property, plant and equipment, at cost	325,813	323,469
Machinery and equipment
Long-lived assets
Property, plant and equipment, at cost	564,171	565,771
Transportation equipment
Long-lived assets
Property, plant and equipment, at cost	22,423	17,774
Office furniture and equipment
Long-lived assets
Property, plant and equipment, at cost	77,453	77,054
Construction in progress
Long-lived assets
Property, plant and equipment, at cost	$ 30,152	$ 17,538