RESTRUCTURING ACTIVITIES - Restructuring Activities - Restruciting Expenses and Related Costs (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 29, 2018
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 7,019
ESS
Restructuring Cost and Reserve [Line Items]
Restructuring charges	5,419
Utility
Restructuring Cost and Reserve [Line Items]
Restructuring charges	1,474
Corporate
Restructuring Cost and Reserve [Line Items]
Restructuring charges	126
Total cost of sales
Restructuring Cost and Reserve [Line Items]
Restructuring charges	4,490
Total cost of sales | ESS
Restructuring Cost and Reserve [Line Items]
Restructuring charges	3,016	$ 18,380
Total cost of sales | Utility
Restructuring Cost and Reserve [Line Items]
Restructuring charges	1,474
Total cost of sales | Corporate
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0
Selling, General and Administrative Expenses
Restructuring Cost and Reserve [Line Items]
Restructuring charges	2,529
Selling, General and Administrative Expenses | ESS
Restructuring Cost and Reserve [Line Items]
Restructuring charges	2,403	$ 15,651
Selling, General and Administrative Expenses | Utility
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0
Selling, General and Administrative Expenses | Corporate
Restructuring Cost and Reserve [Line Items]
Restructuring charges	126
Severance | Total cost of sales
Restructuring Cost and Reserve [Line Items]
Restructuring charges	2,118
Severance | Total cost of sales | ESS
Restructuring Cost and Reserve [Line Items]
Restructuring charges	1,603
Severance | Total cost of sales | Utility
Restructuring Cost and Reserve [Line Items]
Restructuring charges	515
Severance | Total cost of sales | Corporate
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0
Severance | Selling, General and Administrative Expenses
Restructuring Cost and Reserve [Line Items]
Restructuring charges	1,533
Severance | Selling, General and Administrative Expenses | ESS
Restructuring Cost and Reserve [Line Items]
Restructuring charges	1,533
Severance | Selling, General and Administrative Expenses | Utility
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0
Severance | Selling, General and Administrative Expenses | Corporate
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0
Other cash restructuring expenses | Total cost of sales
Restructuring Cost and Reserve [Line Items]
Restructuring charges	1,111
Other cash restructuring expenses | Total cost of sales | ESS
Restructuring Cost and Reserve [Line Items]
Restructuring charges	152
Other cash restructuring expenses | Total cost of sales | Utility
Restructuring Cost and Reserve [Line Items]
Restructuring charges	959
Other cash restructuring expenses | Total cost of sales | Corporate
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0
Other cash restructuring expenses | Selling, General and Administrative Expenses
Restructuring Cost and Reserve [Line Items]
Restructuring charges	611
Other cash restructuring expenses | Selling, General and Administrative Expenses | ESS
Restructuring Cost and Reserve [Line Items]
Restructuring charges	485
Other cash restructuring expenses | Selling, General and Administrative Expenses | Utility
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0
Other cash restructuring expenses | Selling, General and Administrative Expenses | Corporate
Restructuring Cost and Reserve [Line Items]
Restructuring charges	126
Asset impairments/net loss on disposals | Total cost of sales
Restructuring Cost and Reserve [Line Items]
Restructuring charges	1,261
Asset impairments/net loss on disposals | Total cost of sales | ESS
Restructuring Cost and Reserve [Line Items]
Restructuring charges	1,261
Asset impairments/net loss on disposals | Total cost of sales | Utility
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0
Asset impairments/net loss on disposals | Total cost of sales | Corporate
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0
Asset impairments/net loss on disposals | Selling, General and Administrative Expenses
Restructuring Cost and Reserve [Line Items]
Restructuring charges	385
Asset impairments/net loss on disposals | Selling, General and Administrative Expenses | ESS
Restructuring Cost and Reserve [Line Items]
Restructuring charges	385
Asset impairments/net loss on disposals | Selling, General and Administrative Expenses | Utility
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0
Asset impairments/net loss on disposals | Selling, General and Administrative Expenses | Corporate
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 0