PROPERTY, PLANT AND EQUIPMENT - (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Total	$ 449,074		$ 449,074		$ 447,796
Accumulated depreciation	(267,764)		(267,764)		(255,845)
Property, plant and equipment, net	181,310		181,310		191,951
Assets under finance leases	5,700		5,700		5,600
Accumulated amortization for assets under finance leases	700		700		500
Depreciation expense	7,800	$ 8,700	15,900	$ 17,300
Land
Property, Plant and Equipment [Line Items]
Total	6,366		6,366		6,380
Buildings and leasehold improvements
Property, Plant and Equipment [Line Items]
Total	58,664		58,664		59,177
Machinery and equipment
Property, Plant and Equipment [Line Items]
Total	291,428		291,428		284,020
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Total	11,014		11,014		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	18,809		18,809		22,906
Vehicles
Property, Plant and Equipment [Line Items]
Total	4,472		4,472		4,642
Construction in progress
Property, Plant and Equipment [Line Items]
Total	$ 12,404		$ 12,404		$ 13,088