RESTRUCTURING ACTIVITIES (Details) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 29, 2019 facility	Dec. 28, 2019 USD ($)
Restructuring Cost and Reserve [Line Items]
Restructuring charges		$ 34,031
Facility Closing
Restructuring Cost and Reserve [Line Items]
Number of facilities closed | facility	7
ESS
Restructuring Cost and Reserve [Line Items]
Restructuring charges		28,572
ESS | Facility Closing
Restructuring Cost and Reserve [Line Items]
Number of facilities closed | facility	1
ESS | Restructuring Asset Impairment
Restructuring Cost and Reserve [Line Items]
Impairments of current and other assets		7,944
Utility Support Structures Segment
Restructuring Cost and Reserve [Line Items]
Restructuring charges		5,153
Utility Support Structures Segment | Facility Closing
Restructuring Cost and Reserve [Line Items]
Number of facilities closed | facility	1
Irrigation
Restructuring Cost and Reserve [Line Items]
Restructuring charges		180
Other/ Corporate
Restructuring Cost and Reserve [Line Items]
Restructuring charges		126
Cost of Sales
Restructuring Cost and Reserve [Line Items]
Restructuring charges		18,380
Cost of Sales | Severance
Restructuring Cost and Reserve [Line Items]
Restructuring charges		8,080
Cost of Sales | Other cash restructuring expenses
Restructuring Cost and Reserve [Line Items]
Restructuring charges		5,740
Cost of Sales | Impairments of fixed assets/net loss on disposals
Restructuring Cost and Reserve [Line Items]
Restructuring charges		4,560
Cost of Sales | ESS
Restructuring Cost and Reserve [Line Items]
Restructuring charges		14,327
Cost of Sales | ESS | Severance
Restructuring Cost and Reserve [Line Items]
Restructuring charges		6,255
Cost of Sales | ESS | Other cash restructuring expenses
Restructuring Cost and Reserve [Line Items]
Restructuring charges		3,512
Cost of Sales | ESS | Impairments of fixed assets/net loss on disposals
Restructuring Cost and Reserve [Line Items]
Restructuring charges		4,560
Cost of Sales | Utility Support Structures Segment
Restructuring Cost and Reserve [Line Items]
Restructuring charges		4,053
Cost of Sales | Utility Support Structures Segment | Severance
Restructuring Cost and Reserve [Line Items]
Restructuring charges		1,825
Cost of Sales | Utility Support Structures Segment | Other cash restructuring expenses
Restructuring Cost and Reserve [Line Items]
Restructuring charges		2,228
Cost of Sales | Utility Support Structures Segment | Impairments of fixed assets/net loss on disposals
Restructuring Cost and Reserve [Line Items]
Restructuring charges		0
Cost of Sales | Irrigation
Restructuring Cost and Reserve [Line Items]
Restructuring charges		0
Cost of Sales | Irrigation | Severance
Restructuring Cost and Reserve [Line Items]
Restructuring charges		0
Cost of Sales | Irrigation | Other cash restructuring expenses
Restructuring Cost and Reserve [Line Items]
Restructuring charges		0
Cost of Sales | Irrigation | Impairments of fixed assets/net loss on disposals
Restructuring Cost and Reserve [Line Items]
Restructuring charges		0
Cost of Sales | Other/ Corporate
Restructuring Cost and Reserve [Line Items]
Restructuring charges		0
Cost of Sales | Other/ Corporate | Severance
Restructuring Cost and Reserve [Line Items]
Restructuring charges		0
Cost of Sales | Other/ Corporate | Other cash restructuring expenses
Restructuring Cost and Reserve [Line Items]
Restructuring charges		0
Cost of Sales | Other/ Corporate | Impairments of fixed assets/net loss on disposals
Restructuring Cost and Reserve [Line Items]
Restructuring charges		0
Selling, General and Administrative Expenses
Restructuring Cost and Reserve [Line Items]
Restructuring charges		15,651
Selling, General and Administrative Expenses | Severance
Restructuring Cost and Reserve [Line Items]
Restructuring charges		11,883
Selling, General and Administrative Expenses | Other cash restructuring expenses
Restructuring Cost and Reserve [Line Items]
Restructuring charges		3,328
Selling, General and Administrative Expenses | Impairments of fixed assets/net loss on disposals
Restructuring Cost and Reserve [Line Items]
Restructuring charges		440
Selling, General and Administrative Expenses | ESS
Restructuring Cost and Reserve [Line Items]
Restructuring charges		14,245
Selling, General and Administrative Expenses | ESS | Severance
Restructuring Cost and Reserve [Line Items]
Restructuring charges		10,654
Selling, General and Administrative Expenses | ESS | Other cash restructuring expenses
Restructuring Cost and Reserve [Line Items]
Restructuring charges		3,151
Selling, General and Administrative Expenses | ESS | Impairments of fixed assets/net loss on disposals
Restructuring Cost and Reserve [Line Items]
Restructuring charges		440
Selling, General and Administrative Expenses | Utility Support Structures Segment
Restructuring Cost and Reserve [Line Items]
Restructuring charges		1,100
Selling, General and Administrative Expenses | Utility Support Structures Segment | Severance
Restructuring Cost and Reserve [Line Items]
Restructuring charges		1,100
Selling, General and Administrative Expenses | Utility Support Structures Segment | Other cash restructuring expenses
Restructuring Cost and Reserve [Line Items]
Restructuring charges		0
Selling, General and Administrative Expenses | Utility Support Structures Segment | Impairments of fixed assets/net loss on disposals
Restructuring Cost and Reserve [Line Items]
Restructuring charges		0
Selling, General and Administrative Expenses | Irrigation
Restructuring Cost and Reserve [Line Items]
Restructuring charges		180
Selling, General and Administrative Expenses | Irrigation | Severance
Restructuring Cost and Reserve [Line Items]
Restructuring charges		129
Selling, General and Administrative Expenses | Irrigation | Other cash restructuring expenses
Restructuring Cost and Reserve [Line Items]
Restructuring charges		51
Selling, General and Administrative Expenses | Irrigation | Impairments of fixed assets/net loss on disposals
Restructuring Cost and Reserve [Line Items]
Restructuring charges		0
Selling, General and Administrative Expenses | Other/ Corporate
Restructuring Cost and Reserve [Line Items]
Restructuring charges		126
Selling, General and Administrative Expenses | Other/ Corporate | Severance
Restructuring Cost and Reserve [Line Items]
Restructuring charges		0
Selling, General and Administrative Expenses | Other/ Corporate | Other cash restructuring expenses
Restructuring Cost and Reserve [Line Items]
Restructuring charges		126
Selling, General and Administrative Expenses | Other/ Corporate | Impairments of fixed assets/net loss on disposals
Restructuring Cost and Reserve [Line Items]
Restructuring charges		$ 0
CHINA | Facility Closing
Restructuring Cost and Reserve [Line Items]
Number of facilities closed | facility	3