INCOME TAXES - TEMPORARY DIFFERENCES TO THE COMPONENTS OF DEFERRED TAX ASSETS (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Inventory	$ 1,321	$ 1,172
Accrued compensation	103	114
Stock and Stock Options	914	811
Research and development tax credit	442	438
Alternative minimum tax credit	0	543
Deferred revenue	2,002	2,934
Property and equipment	2,531	2,750
Net operating loss carryforwards – domestic	22,627	34,706
Foreign tax credit carryforward	54	0
Capital leases	(3,757)	(2,833)
Unremitted earnings for controlled foreign corporations	(50)	0
Other	194	34
Deferred tax assets, gross	26,381	40,669
Valuation allowance	(14,504)	(19,547)
Total net deferred tax assets	$ 11,877	$ 21,122