PROPERTY, PLANT AND EQUIPMENT - (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Total	$ 449,539		$ 449,539		$ 447,796
Accumulated depreciation	(276,490)		(276,490)		(255,845)
Property, plant and equipment, net	173,049		173,049		191,951
Assets under finance leases	5,700		5,700		5,600
Accumulated amortization for assets under finance leases	800		800		500
Depreciation expense	7,900	$ 8,400	23,800	$ 25,700
Land
Property, Plant and Equipment [Line Items]
Total	5,763		5,763		6,380
Buildings and leasehold improvements
Property, Plant and Equipment [Line Items]
Total	56,020		56,020		59,177
Machinery and equipment
Property, Plant and Equipment [Line Items]
Total	295,870		295,870		284,020
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Total	10,896		10,896		10,946
Capitalized Enterprise Resource Planning system development costs
Property, Plant and Equipment [Line Items]
Total	45,917		45,917		46,637
Computers and computer software
Property, Plant and Equipment [Line Items]
Total	19,082		19,082		22,906
Vehicles
Property, Plant and Equipment [Line Items]
Total	4,493		4,493		4,642
Construction in progress
Property, Plant and Equipment [Line Items]
Total	$ 11,498		$ 11,498		$ 13,088