EARNINGS PER SHARE (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jul. 01, 2017	Jun. 25, 2016	Jul. 01, 2017	Jun. 25, 2016
Basic EPS
Net earnings attributable to Valmont Industries, Inc.	$ 45,664,000	$ 42,026,000	$ 84,643,000	$ 74,995,000
Shares outstanding basic (in shares)	22,517,000	22,602,000	22,494,000	22,651,000
Per share amount basic (in dollars per share)	$ 2.03	$ 1.86	$ 3.76	$ 3.31
Dilutive Effect of Stock Options
Dilutive Effect of Stock Options	$ 0	$ 0	$ 0	$ 0
Dilutive effect of stock options number of shares (in shares)	223,000	147,000	206,000	131,000
Dilutive effect of stock options (in dollars per share)	$ (0.02)	$ (0.01)	$ (0.03)	$ (0.02)
Diluted EPS
Diluted EPS			$ 84,643,000	$ 74,995,000
Shares outstanding dilutive (in shares)	22,740,000	22,749,000	22,700,000	22,782,000
Per share amount diluted (in dollars per share)	$ 2.01	$ 1.85	$ 3.73	$ 3.29
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)			84,712	381,973