PROPERTY, PLANT AND EQUIPMENT - Summary of Property, Plant and Equipment (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Total	$ 432,064		$ 432,064		$ 416,611
Accumulated depreciation and amortization	(239,245)		(239,245)		(221,817)
Property, plant and equipment, net	192,819		192,819		194,794
Assets under finance leases, net of accumulated amortization	5,336		5,336		5,200
Depreciation expense	8,700	$ 8,800	17,300	$ 18,100
Land
Property, Plant and Equipment [Line Items]
Total	6,386		6,386		6,376
Buildings and leasehold improvements
Property, Plant and Equipment [Line Items]
Total	58,788		58,788		57,006
Machinery and equipment
Property, Plant and Equipment [Line Items]
Total	275,460		275,460		269,084
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Total	10,706		10,706		10,253
Capitalized ERP system development costs
Property, Plant and Equipment [Line Items]
Total	46,637		46,637		46,637
Computers and computer software
Property, Plant and Equipment [Line Items]
Total	17,463		17,463		15,826
Automobiles
Property, Plant and Equipment [Line Items]
Total	4,728		4,728		4,879
Construction in progress
Property, Plant and Equipment [Line Items]
Total	$ 11,896		$ 11,896		$ 6,550