GOODWILL AND INTANGIBLE ASSETS - Carrying Amount of Goodwill by Segment (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 25, 2021	Dec. 26, 2020
Goodwill
Gross balance, beginning		$ 492,144
Accumulated impairment losses		(61,822)
Balance, ending	$ 709,462	430,322
Carrying amount of goodwill
Balance at the beginning of the period	430,322
Acquisitions	280,659
Foreign currency translation	(1,519)
Balance at the end of the period	709,462
Engineered Support Structures Segment
Goodwill
Gross balance, beginning		232,323
Accumulated impairment losses		(31,245)
Balance, ending	201,248	201,078
Carrying amount of goodwill
Balance at the beginning of the period	201,078
Acquisitions	0
Foreign currency translation	170
Balance at the end of the period	201,248
Utility Support Structures Segment
Goodwill
Gross balance, beginning		135,335
Accumulated impairment losses		(14,355)
Balance, ending	119,249	120,980
Carrying amount of goodwill
Balance at the beginning of the period	120,980
Acquisitions	0
Foreign currency translation	(1,731)
Balance at the end of the period	119,249
Coatings Segment
Goodwill
Gross balance, beginning		94,309
Accumulated impairment losses		(16,222)
Balance, ending	78,216	78,087
Carrying amount of goodwill
Balance at the beginning of the period	78,087
Acquisitions	0
Foreign currency translation	129
Balance at the end of the period	78,216
Irrigation Segment
Goodwill
Gross balance, beginning		30,177
Accumulated impairment losses		0
Balance, ending	310,749	$ 30,177
Carrying amount of goodwill
Balance at the beginning of the period	30,177
Acquisitions	280,659
Foreign currency translation	(87)
Balance at the end of the period	$ 310,749