PARTY-IN-INTEREST TRANSACTIONS (Details) - EMPLOYEE RETIREMENT SAVINGS PLAN - USD ($)	12 Months Ended
Dec. 31, 2025	Dec. 31, 2024
PARTY-IN-INTEREST TRANSACTIONS
Fees paid by Plan participants	$ 823,003	$ 823,846
Fidelity
PARTY-IN-INTEREST TRANSACTIONS
Fees paid by Plan participants	$ 823,003	$ 823,846
Valmont Industries, Inc. common stock \| Employer
PARTY-IN-INTEREST TRANSACTIONS
Number of shares held	95,188	104,852
Investment at cost basis	$ 10,406,133	$ 10,699,557
Dividend income	$ 267,388	$ 268,348

Amount of decrease in net asset available for benefit from administrative expense incurred by employee stock purchase, saving, or similar plan (employee benefit plan (EBP)).

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Amount of increase in net asset available for benefit from dividend income on investment held by employee stock purchase, saving, or similar plan (employee benefit plan (EBP)).

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Cost of investment, excluding plan interest in master trust, held by employee stock purchase, saving, or similar plan (employee benefit plan (EBP)). Includes, but is not limited to, derivative, investment measured at net asset value per share as practical expedient, and insurance contract.

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