PROPERTY, PLANT AND EQUIPMENT (Details) - USD ($) $ in Thousands	Jun. 30, 2018		Dec. 31, 2017		Jun. 30, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Total cost	$ 349,083		$ 354,452
Less: accumulated depreciation	(252,302)		(250,804)
Total net book value	96,781	[1]	103,648	[1]	$ 95,659	$ 89,080
Assets held under capital leases (included in the above)	17,445		14,193
Less: accumulated depreciation	(6,578)		(5,151)
Total net book value	10,867		9,042
Land and buildings
Property, Plant and Equipment [Line Items]
Total cost	83,712		86,480
Machinery, fixtures and equipment
Property, Plant and Equipment [Line Items]
Total cost	195,089		195,682
Assets held under capital leases (included in the above)	17,445		14,193
Other equipment
Property, Plant and Equipment [Line Items]
Total cost	15,741		16,121
Software
Property, Plant and Equipment [Line Items]
Total cost	53,033		53,143
Construction in progress
Property, Plant and Equipment [Line Items]
Total cost	$ 1,508		$ 3,026

[1] (1) Reflects property, plant and equipment, net