ACQUISITIONS - Acquisitions of Redeemable Noncontrolling Interests (Details) $ / shares in Units, R$ in Thousands, $ in Thousands	3 Months Ended			12 Months Ended
	Mar. 28, 2026 USD ($)	Dec. 27, 2025 USD ($) $ / shares	Sep. 27, 2025 USD ($)	Dec. 27, 2025 USD ($) $ / shares	Dec. 27, 2025 BRL (R$)
ACQUISITIONS
Mandatorily redeemable financial instrument		$ 8,922		$ 8,922
ConcealFab
ACQUISITIONS
Percentage acquired		40.00%		40.00%	40.00%
Consideration transferred		$ 81,822
Amount paid for repurchase of redeemable noncontrolling interests	$ 8,922	$ 72,900
Valmont Substations, LLC
ACQUISITIONS
Percentage acquired			30.00%
Consideration transferred			$ 14,624
Solbras Energia Solar do Brasil S.A.
ACQUISITIONS
Percentage acquired		45.00%		45.00%	45.00%
Redeemable amount		$ 14,246		$ 14,246	R$ 79,000
Retained earnings		$ 11,997		$ 11,997
Earnings per share, diluted | $ / shares		$ 0.61		$ 0.6