PROPERTY, PLANT AND EQUIPMENT (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 416,611	$ 402,742
Accumulated depreciation and amortization	(221,817)	(199,523)
Property, plant and equipment, net	194,794	203,219
Building under capital lease	5,300
Depreciation	36,200	35,700	$ 33,500
Land
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	6,376	6,698
Buildings and leasehold improvements
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	57,006	47,924
Machinery and equipment
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	269,084	261,343
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	10,253	9,405
Capitalized ERP system development costs
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	46,637	46,637
Computers and computer software
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	15,826	13,052
Automobiles
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	4,879	5,070
Construction in progress
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	6,550	$ 12,613
Building under capital lease
Property, Plant and Equipment [Line Items]
Accumulated depreciation and amortization	$ (100)