EARNINGS PER SHARE - Reconciliation of earnings and share amounts to compute basic and diluted earnings per share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 30, 2023	Dec. 31, 2022	Dec. 25, 2021
Earnings Per Share [Abstract]
Net earnings attributable to Valmont Industries, Inc.	$ 150,849	$ 250,863	$ 195,630
Change in redemption value of redeemable noncontrolling interest	(7,374)
Net earnings attributable to Valmont Industries, Inc. including change in redemption value of redeemable noncontrolling interest	$ 143,475	$ 250,863	$ 195,630
Weighted average shares outstanding:
Basic (in shares)	20,956	21,311	21,193
Dilutive effect of various stock awards (in shares)	203	269	300
Diluted (in shares)	21,159	21,580	21,493
Earnings (loss) per share:
Basic (in dollars per share)	$ 6.85	$ 11.77	$ 9.23
Dilutive effect of various stock awards (in dollars per share)	(0.07)	(0.15)	(0.13)
Diluted (in dollars per share)	$ 6.78	$ 11.62	$ 9.10