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	3 Months Ended
	Mar. 30, 2024	Apr. 01, 2023
Earnings per share:
Net earnings attributable to Valmont Industries, Inc.	$ 87,822	$ 74,540
Net earnings attributable to Valmont Industries, Inc. including change in redemption value of redeemable noncontrolling interest	$ 87,822	$ 74,540
Weighted average shares outstanding (000s):
Basic (in shares)	20,188	21,269
Dilutive effect of various stock awards (in shares)	133	243
Diluted (in shares)	20,321	21,512
Net earnings per share attributable to common shareholders:
Basic (in dollars per share)	$ 4.35	$ 3.50
Dilutive effect of various stock awards (in dollars per share)	(0.03)	(0.03)
Diluted (in dollars per share)	$ 4.32	$ 3.47