INCOME TAXES - DEFERRED TAX ASSETS (LIABILITIES) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets:
Loss and credit carry-forwards	$ 0	$ 7,722	$ 9,169
Stock-based compensation	636	549	519
Inventory Reserve	115	494	534
Intangibles	146	0	0
Other	744	178	263
Total deferred tax assets	1,641	8,943	10,485
Valuation allowance	(1,491)	(8,756)	(10,185)
Total deferred tax assets, net of valuation allowance	150	187	300
Deferred tax liabilities:
State taxes (capital)	0	(17)	(19)
Property and equipment	(150)	(294)	(459)
Intangibles	0	(244)	(386)
Total deferred tax liabilities	(150)	(555)	(864)
Net deferred tax liabilities	$ 0	$ (368)	$ (564)