PROPERTY, PLANT AND EQUIPMENT - Summary of Property, Plant and Equipment (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Total	$ 422,931		$ 416,611
Accumulated depreciation and amortization	(230,364)		(221,817)
Property, plant and equipment, net	192,567		194,794
Building under finance lease	5,200
Depreciation expense	8,600	$ 9,300
Land
Property, Plant and Equipment [Line Items]
Total	6,372		6,376
Buildings and leasehold improvements
Property, Plant and Equipment [Line Items]
Total	57,906		57,006
Machinery and equipment
Property, Plant and Equipment [Line Items]
Total	271,652		269,084
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Total	10,444		10,253
Capitalized ERP system development costs
Property, Plant and Equipment [Line Items]
Total	46,637		46,637
Computers and computer software
Property, Plant and Equipment [Line Items]
Total	17,127		15,826
Automobiles
Property, Plant and Equipment [Line Items]
Total	4,736		4,879
Construction in progress
Property, Plant and Equipment [Line Items]
Total	8,057		$ 6,550
Building under finance lease
Property, Plant and Equipment [Line Items]
Accumulated depreciation and amortization	$ (100)