EARNINGS PER SHARE (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 26, 2015	Sep. 27, 2014	Sep. 26, 2015	Sep. 27, 2014
Basic EPS
Net earnings attributable to Valmont Industries, Inc.	$ 12,066,000	$ 23,559,000	$ 70,678,000	$ 143,515,000
Shares outstanding basic (in shares)	23,057,000	25,287,000	23,420,000	26,208,000
Per share amount basic (in dollars per share)	$ 0.52	$ 0.93	$ 3.02	$ 5.48
Dilutive Effect of Stock Options
Dilutive Effect of Stock Options	$ 0	$ 0	$ 0	$ 0
Dilutive effect of stock options number of shares (in shares)	113,000	226,000	114,000	231,000
Dilutive effect of stock options (in dollars per share)	$ 0.00	$ (0.01)	$ (0.02)	$ (0.05)
Diluted EPS
Diluted EPS	$ 12,066,000	$ 23,559,000	$ 70,678,000	$ 143,515,000
Shares outstanding dilutive (in shares)	23,170,000	25,513,000	23,534,000	26,439,000
Per share amount diluted (in dollars per share)	$ 0.52	$ 0.92	$ 3.00	$ 5.43
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)			433,401	273,170