GOODWILL AND INTANGIBLE ASSETS - Carrying Amount of Goodwill by Segment (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 26, 2021	Dec. 26, 2020
Goodwill
Gross balance, beginning		$ 492,144
Accumulated impairment losses		(61,822)
Balance, ending	$ 712,731	430,322
Carrying amount of goodwill
Balance at the beginning of the period	430,322
Acquisitions	280,659
Foreign currency translation	1,750
Balance at the end of the period	712,731
Engineered Support Structures Segment
Goodwill
Gross balance, beginning		232,323
Accumulated impairment losses		(31,245)
Balance, ending	203,026	201,078
Carrying amount of goodwill
Balance at the beginning of the period	201,078
Acquisitions	0
Foreign currency translation	1,948
Balance at the end of the period	203,026
Utility Support Structures Segment
Goodwill
Gross balance, beginning		135,335
Accumulated impairment losses		(14,355)
Balance, ending	120,046	120,980
Carrying amount of goodwill
Balance at the beginning of the period	120,980
Acquisitions	0
Foreign currency translation	(934)
Balance at the end of the period	120,046
Coatings Segment
Goodwill
Gross balance, beginning		94,309
Accumulated impairment losses		(16,222)
Balance, ending	78,597	78,087
Carrying amount of goodwill
Balance at the beginning of the period	78,087
Acquisitions	0
Foreign currency translation	510
Balance at the end of the period	78,597
Irrigation Segment
Goodwill
Gross balance, beginning		30,177
Accumulated impairment losses		0
Balance, ending	311,062	$ 30,177
Carrying amount of goodwill
Balance at the beginning of the period	30,177
Acquisitions	280,659
Foreign currency translation	226
Balance at the end of the period	$ 311,062