Income Taxes - Significant Components of Net Deferred Income Taxes (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Deferred tax assets:
Allowance for doubtful accounts	$ 12	$ 152
Inventory reserves	3,855	3,289
Accrued liabilities	11	382
Warrant interest expense	269	269
Stock compensation expense	2,774	2,478
State net operating loss-net of tax	9,189	7,456
Net operating loss carryforward	50,284	40,417
Tax credits	825	671
Depreciation	4,995
Valuation allowance	(72,199)	(52,286)
Total deferred tax assets	15	2,828
Deferred tax liability:
Depreciation		(3,320)
Prepaid expenses	$ (15)	(62)
Net deferred tax liability		$ (554)