GOODWILL AND INTANGIBLE ASSETS - Carrying Amount of Goodwill by Segment (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 26, 2015	Jun. 27, 2015	Sep. 26, 2015
Carrying amount of goodwill
Balance at the beginning of the period			$ 385,111
Impairment			(9,100)
Foreign currency translation			(11,591)
Divestiture of business			(1,737)
Balance at the end of the period	$ 362,683		362,683
Engineered Infrastructure Products Segment
Carrying amount of goodwill
Balance at the beginning of the period			197,074
Impairment			0
Foreign currency translation			(8,840)
Divestiture of business		$ (1,737)	(1,737)
Balance at the end of the period	186,497		186,497
Utility Support Structures Segment
Carrying amount of goodwill
Balance at the beginning of the period			75,404
Impairment			0
Foreign currency translation			0
Divestiture of business			0
Balance at the end of the period	75,404		75,404
Coatings Segment
Carrying amount of goodwill
Balance at the beginning of the period			74,862
Impairment	(9,100)		(9,100)
Foreign currency translation			(2,145)
Divestiture of business			0
Balance at the end of the period	63,617		63,617
Irrigation Segment
Carrying amount of goodwill
Balance at the beginning of the period			19,536
Impairment			0
Foreign currency translation			(196)
Divestiture of business			0
Balance at the end of the period	19,340		19,340
Other
Carrying amount of goodwill
Balance at the beginning of the period			18,235
Impairment			0
Foreign currency translation			(410)
Divestiture of business			0
Balance at the end of the period	17,825		17,825
Access Systems
Carrying amount of goodwill
Balance at the end of the period	$ 70,000		$ 70,000