PROPERTY, PLANT AND EQUIPMENT (Details) (USD $) In Thousands, unless otherwise specified	Dec. 27, 2014	Dec. 28, 2013
Long-lived assets
Property, plant and equipment, at cost	$ 1,139,569	$ 1,017,126
Land and improvements
Long-lived assets
Property, plant and equipment, at cost	82,372	71,726
Buildings and improvements
Long-lived assets
Property, plant and equipment, at cost	327,863	265,112
Machinery and equipment
Long-lived assets
Property, plant and equipment, at cost	593,387	520,262
Transportation equipment
Long-lived assets
Property, plant and equipment, at cost	35,205	37,213
Office furniture and equipment
Long-lived assets
Property, plant and equipment, at cost	76,589	73,200
Construction in progress
Long-lived assets
Property, plant and equipment, at cost	$ 24,153	$ 49,613