EARNINGS PER SHARE - Schedule of Reconciliation of Basic and Diluted Earnings Per Share (EPS) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 25, 2021	Dec. 26, 2020	Dec. 28, 2019
Basic EPS
Net earnings attributable to Valmont Industries, Inc.	$ 195,630	$ 140,693	$ 146,408
Shares outstanding basic (in shares)	21,193	21,315	21,659
Per share amount basic (in dollars per share)	$ 9.23	$ 6.60	$ 6.76
Dilutive Effect of Stock Options
Dilutive Effect of Stock Options	$ 0	$ 0	$ 0
Dilutive effect of stock options number of shares (in shares)	300	110	110
Dilutive effect of stock options (in dollars per share)	$ 0.13	$ 0.03	$ 0.03
Diluted EPS
Diluted EPS	$ 195,630	$ 140,693	$ 146,408
Shares outstanding dilutive (in shares)	21,493	21,425	21,769
Per share amount diluted (in dollars per share)	$ 9.10	$ 6.57	$ 6.73