BUSINESS SEGMENTS (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 25, 2021 USD ($)	Sep. 26, 2020 USD ($)	Sep. 25, 2021 USD ($) segment	Sep. 26, 2020 USD ($)
Business Segments
Number of reportable segments | segment			4
Net sales	$ 868,782	$ 733,970	$ 2,538,297	$ 2,096,978
Operating income	76,195	61,479	236,031	171,814
Utility Support Structures Segment
Business Segments
Net sales	276,502	272,479	797,063	723,900
Operating income	24,561	25,881	61,168	75,255
Engineered Support Structures Segment
Business Segments
Net sales	281,049	254,945	772,545	731,184
Operating income	34,383	25,434	86,235	46,183
Coatings Segment
Business Segments
Net sales	74,906	68,698	224,102	199,955
Operating income	12,478	12,416	40,018	33,618
Irrigation Segment
Business Segments
Net sales	236,325	137,848	744,587	441,939
Operating income	27,735	14,687	108,467	60,701
Sales
Business Segments
Sales	894,615	757,144	2,610,402	2,173,505
Sales | Utility Support Structures Segment
Business Segments
Sales	276,502	274,393	797,498	731,178
Sales | Utility Support Structures Segment | Steel
Business Segments
Sales	199,946	156,082	545,417	482,430
Sales | Utility Support Structures Segment | Concrete
Business Segments
Sales	39,656	39,215	123,477	120,653
Sales | Utility Support Structures Segment | Engineered Solar Tracker Solutions
Business Segments
Sales	13,224	43,287	28,690	56,830
Sales | Utility Support Structures Segment | Offshore and Other Complex Steel Structures
Business Segments
Sales	23,676	35,809	99,914	71,265
Sales | Engineered Support Structures Segment
Business Segments
Sales	281,097	255,656	772,813	739,783
Sales | Engineered Support Structures Segment | Lighting, Traffic, and Highway Safety Products
Business Segments
Sales	188,589	181,571	529,432	534,585
Sales | Engineered Support Structures Segment | Communication Products
Business Segments
Sales	63,424	50,677	164,055	139,759
Sales | Engineered Support Structures Segment | Access Systems
Business Segments
Sales	29,084	23,408	79,326	65,439
Sales | Coatings Segment
Business Segments
Sales	96,685	87,886	288,131	255,976
Sales | Irrigation Segment
Business Segments
Sales	240,331	139,209	751,960	446,568
Intersegment sales
Business Segments
Sales	25,833	23,174	72,105	76,527
Intersegment sales | Utility Support Structures Segment
Business Segments
Sales	0	1,914	435	7,278
Intersegment sales | Engineered Support Structures Segment
Business Segments
Sales	48	711	268	8,599
Intersegment sales | Coatings Segment
Business Segments
Sales	21,779	19,188	64,029	56,021
Intersegment sales | Irrigation Segment
Business Segments
Sales	4,006	1,361	7,373	4,629
Other
Business Segments
Operating income	(22,962)	(16,939)	(59,857)	(43,943)
North America | Sales | Irrigation Segment
Business Segments
Sales	116,308	75,803	395,096	281,397
International | Sales | Irrigation Segment
Business Segments
Sales	$ 124,023	$ 63,406	$ 356,864	$ 165,171