Income Taxes (Details 3) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets:
Allowance for doubtful accounts	$ 11	$ 2
Inventory reserves	3,185	3,323
Consumables excess reserve	169	170
Accrued liabilities	52	55
Warrant interest expense	196	196
Stock compensation expense	789	881
State net operating loss	15,010	14,633
Net operating loss carryforward	40,437	38,525
Tax credits	740	740
Depreciation	1,329	2,993
Valuation allowance	(61,869)	(61,512)
Total deferred tax assets	49	6
Deferred tax liability:
Prepaid expenses	(49)	(6)
Net deferred tax liability