RESTRUCTURING ACTIVITIES - Restruciting Expenses and Related Costs (Details) $ in Thousands	12 Months Ended
	Dec. 29, 2018 USD ($)
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 34,031
Cost of Sales
Restructuring Cost and Reserve [Line Items]
Restructuring charges	18,380
Selling, General and Administrative Expenses
Restructuring Cost and Reserve [Line Items]
Restructuring charges	15,651
Severance | Cost of Sales
Restructuring Cost and Reserve [Line Items]
Restructuring charges	8,080
Severance | Selling, General and Administrative Expenses
Restructuring Cost and Reserve [Line Items]
Restructuring charges	11,883
Other cash restructuring expenses | Cost of Sales
Restructuring Cost and Reserve [Line Items]
Restructuring charges	5,740
Other cash restructuring expenses | Selling, General and Administrative Expenses
Restructuring Cost and Reserve [Line Items]
Restructuring charges	3,328
Asset impairments/net loss on disposals | Cost of Sales
Restructuring Cost and Reserve [Line Items]
Restructuring charges	4,560
Asset impairments/net loss on disposals | Selling, General and Administrative Expenses
Restructuring Cost and Reserve [Line Items]
Restructuring charges	440
Engineered Support Structures
Restructuring Cost and Reserve [Line Items]
Restructuring charges	28,572
Engineered Support Structures | Cost of Sales
Restructuring Cost and Reserve [Line Items]
Restructuring charges	14,327
Engineered Support Structures | Selling, General and Administrative Expenses
Restructuring Cost and Reserve [Line Items]
Restructuring charges	14,245
Engineered Support Structures | Severance | Cost of Sales
Restructuring Cost and Reserve [Line Items]
Restructuring charges	6,255
Engineered Support Structures | Severance | Selling, General and Administrative Expenses
Restructuring Cost and Reserve [Line Items]
Restructuring charges	10,654
Engineered Support Structures | Other cash restructuring expenses | Cost of Sales
Restructuring Cost and Reserve [Line Items]
Restructuring charges	3,512
Engineered Support Structures | Other cash restructuring expenses | Selling, General and Administrative Expenses
Restructuring Cost and Reserve [Line Items]
Restructuring charges	3,151
Engineered Support Structures | Asset impairments/net loss on disposals | Cost of Sales
Restructuring Cost and Reserve [Line Items]
Restructuring charges	4,560
Engineered Support Structures | Asset impairments/net loss on disposals | Selling, General and Administrative Expenses
Restructuring Cost and Reserve [Line Items]
Restructuring charges	440
Utility Support Structures
Restructuring Cost and Reserve [Line Items]
Restructuring charges	5,153
Utility Support Structures | Cost of Sales
Restructuring Cost and Reserve [Line Items]
Restructuring charges	4,053
Utility Support Structures | Selling, General and Administrative Expenses
Restructuring Cost and Reserve [Line Items]
Restructuring charges	1,100
Utility Support Structures | Severance | Cost of Sales
Restructuring Cost and Reserve [Line Items]
Restructuring charges	1,825
Utility Support Structures | Severance | Selling, General and Administrative Expenses
Restructuring Cost and Reserve [Line Items]
Restructuring charges	1,100
Utility Support Structures | Other cash restructuring expenses | Cost of Sales
Restructuring Cost and Reserve [Line Items]
Restructuring charges	2,228
Utility Support Structures | Other cash restructuring expenses | Selling, General and Administrative Expenses
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0
Utility Support Structures | Asset impairments/net loss on disposals | Cost of Sales
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0
Utility Support Structures | Asset impairments/net loss on disposals | Selling, General and Administrative Expenses
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0
Irrigation
Restructuring Cost and Reserve [Line Items]
Restructuring charges	180
Irrigation | Cost of Sales
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0
Irrigation | Selling, General and Administrative Expenses
Restructuring Cost and Reserve [Line Items]
Restructuring charges	180
Irrigation | Severance | Selling, General and Administrative Expenses
Restructuring Cost and Reserve [Line Items]
Restructuring charges	129
Irrigation | Other cash restructuring expenses | Cost of Sales
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0
Irrigation | Other cash restructuring expenses | Selling, General and Administrative Expenses
Restructuring Cost and Reserve [Line Items]
Restructuring charges	51
Irrigation | Asset impairments/net loss on disposals | Cost of Sales
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0
Irrigation | Asset impairments/net loss on disposals | Selling, General and Administrative Expenses
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0
Other/ Corporate
Restructuring Cost and Reserve [Line Items]
Restructuring charges	126
Other/ Corporate | Cost of Sales
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0
Other/ Corporate | Selling, General and Administrative Expenses
Restructuring Cost and Reserve [Line Items]
Restructuring charges	126
Other/ Corporate | Severance | Cost of Sales
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0
Other/ Corporate | Severance | Selling, General and Administrative Expenses
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0
Other/ Corporate | Other cash restructuring expenses | Cost of Sales
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0
Other/ Corporate | Other cash restructuring expenses | Selling, General and Administrative Expenses
Restructuring Cost and Reserve [Line Items]
Restructuring charges	126
Other/ Corporate | Asset impairments/net loss on disposals | Cost of Sales
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0
Other/ Corporate | Asset impairments/net loss on disposals | Selling, General and Administrative Expenses
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 0