GOODWILL AND INTANGIBLE ASSETS (Details 2) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 26, 2015
Webforge
Non-amortized intangible assets
Carrying value of trade names	$ 8,624	$ 10,430
Valmont SM
Non-amortized intangible assets
Carrying value of trade names	8,765	8,919
Newmark
Non-amortized intangible assets
Carrying value of trade names	11,111	11,111
Ingal EPS/Ingal Civil Products
Non-amortized intangible assets
Carrying value of trade names	7,032	8,504
Donhad
Non-amortized intangible assets
Carrying value of trade names	5,305	6,415
Shakespeare
Non-amortized intangible assets
Carrying value of trade names	4,000	4,000
Industrial Galvanizers
Non-amortized intangible assets
Carrying value of trade names	2,201	2,662
Other
Non-amortized intangible assets
Carrying value of trade names	13,747	13,889
Trade Names
Non-amortized intangible assets
Carrying value of trade names	$ 60,785	$ 65,930