BUSINESS SEGMENTS (Details) $ in Thousands	3 Months Ended
Mar. 27, 2021 USD ($) segment	Mar. 28, 2020 USD ($)
Business Segments
Number of reportable segments \| segment	4
Net sales	$ 774,886	$ 674,200
Operating income	77,211	66,895
Utility Support Structures Segment
Business Segments
Net sales	252,698	222,948
Operating income	21,652	27,724
Engineered Support Structures Segment
Business Segments
Net sales	222,156	227,366
Operating income	19,925	15,931
Coatings Segment
Business Segments
Net sales	71,591	68,590
Operating income	12,872	11,054
Irrigation Segment
Business Segments
Net sales	228,441	155,296
Operating income	38,748	23,663
Sales
Business Segments
Sales	798,412	701,008
Sales \| Utility Support Structures Segment
Business Segments
Sales	253,133	225,461
Sales \| Utility Support Structures Segment \| Steel
Business Segments
Sales	168,497	166,531
Sales \| Utility Support Structures Segment \| Concrete
Business Segments
Sales	40,383	35,785
Sales \| Utility Support Structures Segment \| Engineered Solar Tracker Solutions
Business Segments
Sales	6,294	8,924
Sales \| Utility Support Structures Segment \| Offshore and Other Complex Steel Structures
Business Segments
Sales	37,959	14,221
Sales \| Engineered Support Structures Segment
Business Segments
Sales	222,327	230,742
Sales \| Engineered Support Structures Segment \| Lighting, Traffic, and Highway Safety Products
Business Segments
Sales	153,870	171,987
Sales \| Engineered Support Structures Segment \| Communication Products
Business Segments
Sales	46,079	38,196
Sales \| Engineered Support Structures Segment \| Access Systems
Business Segments
Sales	22,378	20,559
Sales \| Coatings Segment
Business Segments
Sales	93,288	88,085
Sales \| Irrigation Segment
Business Segments
Sales	229,664	156,720
Intersegment sales
Business Segments
Sales	23,526	26,808
Intersegment sales \| Utility Support Structures Segment
Business Segments
Sales	435	2,513
Intersegment sales \| Engineered Support Structures Segment
Business Segments
Sales	171	3,376
Intersegment sales \| Coatings Segment
Business Segments
Sales	21,697	19,495
Intersegment sales \| Irrigation Segment
Business Segments
Sales	1,223	1,424
Other
Business Segments
Operating income	(15,986)	(11,477)
North America \| Sales \| Irrigation Segment
Business Segments
Sales	122,751	106,560
International \| Sales \| Irrigation Segment
Business Segments
Sales	$ 106,913	$ 50,160

Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

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