GOODWILL AND INTANGIBLE ASSETS - Non-Amortized Intangible Assets (Details) - USD ($) $ in Thousands	Dec. 25, 2021	Dec. 26, 2020
Newmark
Non-amortized intangible assets
Carrying value of trade names	$ 11,111	$ 11,111
Webforge
Non-amortized intangible assets
Carrying value of trade names	7,877	7,972
Valmont SM
Non-amortized intangible assets
Carrying value of trade names	6,082	8,720
Ingal EPS/Ingal Civil Products
Non-amortized intangible assets
Carrying value of trade names	7,637	7,730
Shakespeare
Non-amortized intangible assets
Carrying value of trade names	4,000	4,000
Walpar
Non-amortized intangible assets
Carrying value of trade names	3,500	3,500
Convert
Non-amortized intangible assets
Carrying value of trade names	8,479	9,137
Other
Non-amortized intangible assets
Carrying value of trade names	14,721	14,828
Trade Name
Non-amortized intangible assets
Carrying value of trade names	$ 63,407	$ 66,998