4. PROPERTY, PLANT AND EQUIPMENT (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	$ 14,528	$ 14,525
Less: Accumulated depreciation and amortization	(12,160)	(11,921)
Property, plant and equipment, net	2,368	2,604
Building and improvements [Member]
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	$ 285	285
Range of Asset Lives	7 to 36 years
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	$ 906	906
Range of Asset Lives	2 to 5 years
Equipment [Member]
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	$ 12,380	12,343
Range of Asset Lives	2 to 30 years
Furniture, computers and office equipment [Member]
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	$ 907	907
Range of Asset Lives	2 to 8 years
Construction in Progess [Member]
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	$ 50	$ 84