PROPERTY AND EQUIPMENT (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Gross property and equipment	$ 76,157	$ 96,941
Accumulated depreciation	(45,739)	(55,461)
Net property and equipment	30,418	41,480
Medical equipment and facilities
Property, Plant and Equipment [Line Items]
Gross property and equipment	75,657	92,132
Office equipment
Property, Plant and Equipment [Line Items]
Gross property and equipment	330	594
Construction in Progress
Property, Plant and Equipment [Line Items]
Gross property and equipment	170	1,965
Deposits towards purchase of proton beam systems
Property, Plant and Equipment [Line Items]
Gross property and equipment	$ 0	$ 2,250