DISCLOSURES ABOUT THE FAIR VALUE OF FINANCIAL INSTRUMENTS (Details) - USD ($)	Dec. 31, 2016	Dec. 26, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets recorded for the investments held	$ 35,784,000	$ 37,963,000
Liabilities recorded for the investments held	37,963	36,439
Level 1 member
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities	37,800,000	42,697,000
Carrying Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	755,646,000	757,995,000
Trading Securities	37,800,000	42,697,000
Estimated fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	731,633,000	724,020,000
EMD
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of remaining ownership	2,016,000	4,734,000
Valmont Deferred Compensation Plan
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets recorded for the investments held	$ 35,784,000	$ 37,963,000