INCOME TAXES - TEMPORARY DIFFERENCES TO THE COMPONENTS OF DEFERRED TAX ASSETS (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Inventory	$ 2,005	$ 1,249
Accrued compensation	122	110
Stock and Stock Options	1,858	1,281
Research and development tax credit	990	476
Alternative minimum tax credit	0	1,678
Research and development expense	1,417	0
Deferred revenue	2,052	3,305
Property and equipment	3,469	3,065
Net operating loss carryforwards – domestic	11,676	17,088
Foreign tax credit carryforward	64	38
Sales-type leases	(1,968)	(3,936)
Convertible debt equity component	(9,421)	0
Foreign intangible	(691)	0
Other	(179)	0
Deferred tax assets, gross	11,394	24,354
Valuation allowance	(5,656)	(10,233)
Total net deferred tax assets	$ 5,738	$ 14,121