EARNINGS PER SHARE (Details) - USD ($)	3 Months Ended
Mar. 31, 2018	Apr. 01, 2017
Basic EPS
Net earnings attributable to Valmont Industries, Inc.	$ 39,281,000	$ 38,979,000
Shares outstanding basic (in shares)	22,609,000	22,472,000
Per share amount basic (in dollars per share)	$ 1.74	$ 1.73
Dilutive Effect of Stock Options
Dilutive Effect of Stock Options	$ 0	$ 0
Dilutive effect of stock options number of shares (in shares)	187,000	188,000
Dilutive effect of stock options (in dollars per share)	$ (0.02)	$ (0.01)
Diluted EPS
Diluted EPS	$ 39,281,000	$ 38,979,000
Shares outstanding dilutive (in shares)	22,796,000	22,660,000
Per share amount diluted (in dollars per share)	$ 1.72	$ 1.72
Antidilutive Securities
Outstanding stock options with exercise prices exceeding the market price of common stock, excluded from the computation of diluted earnings per share (in shares)		147,554

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

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