PROPERTY AND EQUIPMENT (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 35,977	$ 35,506
Less - accumulated depreciation and amortization	(30,704)	(29,116)
Property, Plant and Equipment, Net, Total	5,273	6,390
Laboratory Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	16,849	16,732
Furniture And Computer Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	2,636	2,565
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 16,492	16,191
Equipment Under Construction [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross		$ 18