PROPERTY, PLANT AND EQUIPMENT (Details) - USD ($) $ in Thousands	Jun. 30, 2020		Dec. 31, 2019		Mar. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Total cost	$ 413,004		$ 424,387
Less: accumulated depreciation	(310,626)		(310,486)
Total net book value	102,378	[1]	113,901	[1]	$ 110,627	$ 117,604
Assets held under capital leases (included in the above)	33,345		35,875
Less: accumulated depreciation	(16,368)		(15,799)
Total net book value	16,977		20,076
Land and buildings
Property, Plant and Equipment [Line Items]
Total cost	98,241		100,502
Assets held under capital leases (included in the above)	0		3,914
Machinery, fixtures and equipment
Property, Plant and Equipment [Line Items]
Total cost	209,633		212,810
Assets held under capital leases (included in the above)	33,345		31,961
Other equipment
Property, Plant and Equipment [Line Items]
Total cost	34,668		36,007
Software
Property, Plant and Equipment [Line Items]
Total cost	68,902		70,294
Construction in progress
Property, Plant and Equipment [Line Items]
Total cost	$ 1,560		$ 4,774

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