EARNINGS PER SHARE - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 30, 2023	Dec. 31, 2022	Dec. 25, 2021
Earnings (Loss) Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Gain (loss) on divestitures	$ 2,994	$ (33,273)
Associated tax benefit		$ 0
Impairment of goodwill and intangible assets	$ 136,457
Impairment of goodwill and intangible assets (in dollars per share)	$ 6.45
Severance and other employee benefit costs	$ 35,210
Realignment charges, after tax	$ 26,490
Restructuring expenses, (in dollars per share)	$ 1.25
Outstanding stock options with exercise prices exceeding the market price of common stock, excluded from the computation of diluted earnings per share (in shares)	127,774	40,564	47,223
Valmont SM, Offshore Wind Business
Earnings (Loss) Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Associated tax benefit		$ 0
Valuation allowance			$ 5,076
Valuation allowance (in dollars per share)			$ 0.24
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
long | Valmont SM, Offshore Wind Business
Earnings (Loss) Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Impairment of goodwill and intangible assets			$ 21,678
Impairment of goodwill and intangible assets (in dollars per share)			$ 1.01