Income Taxes (Details 3) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets:
Allowance for doubtful accounts	$ 2	$ 12
Inventory reserves	3,672	3,855
Accrued liabilities	4	11
Warrant interest expense	196	269
Stock compensation expense	2,022	2,774
State net operating loss - net of tax	15,954	9,189
Net operating loss carryforward	37,856	50,284
Tax credits	999	825
Depreciation	5,117	4,995
Valuation allowance	(65,817)	(72,199)
Total deferred tax assets	5	15
Deferred tax liability:
Prepaid expenses	(5)	(15)
Net deferred tax liability