EARNINGS PER SHARE - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 28, 2024	Dec. 30, 2023	Dec. 31, 2022
Earnings (Loss) Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Impairment of goodwill and other intangible assets, after tax		$ 136,457
Impairment of goodwill and intangible assets (in dollars per share)		$ 6.45
Realignment charges, after tax		$ 26,490
Restructuring expenses, (in dollars per share)		$ 1.25
Gain (loss) on divestitures	$ (4,474)	$ 2,994	$ (33,273)
Associated tax benefit			$ 0
Outstanding stock options with exercise prices exceeding the market price of common stock, excluded from the computation of diluted earnings per share (in shares)	44,620	127,774	40,564
Valmont SM, Offshore Wind Business
Earnings (Loss) Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Associated tax benefit			$ 0
Offshore and Other Complex Steel Structures | Valmont SM, Offshore Wind Business
Earnings (Loss) Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Gain (loss) on divestitures			$ 33,273
Loss from divestiture of offshore wind energy structures business, per share			$ 1.54