Income Taxes (Details 3) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred tax assets:
Allowance for doubtful accounts	$ 2	$ 2
Inventory reserves	3,323	3,672
Consumables excess reserve	170
Accrued liabilities	55	4
Warrant interest expense	196	196
Stock compensation expense	881	2,022
State net operating loss	14,633	15,954
Net operating loss carryforward	38,525	37,856
Tax credits	740	999
Depreciation	2,993	5,117
Valuation allowance	(61,512)	(65,817)
Total deferred tax assets	6	5
Deferred tax liability:
Prepaid expenses	(6)	(5)
Net deferred tax liability