GOODWILL AND INTANGIBLE ASSETS (Details 2) - USD ($) $ in Thousands	Dec. 30, 2017	Dec. 31, 2016
Webforge
Non-amortized intangible assets
Carrying value of trade names	$ 9,432	$ 8,624
Valmont SM
Non-amortized intangible assets
Carrying value of trade names	9,973	8,765
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	7,690	7,032
Donhad
Non-amortized intangible assets
Carrying value of trade names	5,801	5,305
Shakespeare
Non-amortized intangible assets
Carrying value of trade names	4,000	4,000
Other
Non-amortized intangible assets
Carrying value of trade names	16,846	15,948
Trade Names
Non-amortized intangible assets
Carrying value of trade names	$ 64,853	$ 60,785