Income Taxes (Tables)

12 Months Ended

Dec. 31, 2017

Income Taxes

Schedule of reconciliation of statutory federal income tax rate

	Year Ended December 31,
	2017		2016		2015
Tax at statutory federal rate	(34.0)	%	(34.0)	%	(34.0)	%
State taxes, net of federal benefit	(1.4)		(1.5)		(1.9)
Stock-based compensation	(0.8)		1.3		0.8
Nondeductible fair value adjustment	—		(2.5)		—
Nondeductible interest	—		2.0		—
Change in valuation allowance	(34.2)		33.3		34.3
Federal tax rate change	70.2		—		—
Other	0.2		1.4		0.8
Provision for income taxes	(0.0)	%	(0.0)	%	(0.0)	%

Schedule of tax effects of temporary differences and carryforwards

The tax effects of temporary differences and carryforwards that give rise to significant portions of the deferred tax assets are as follows (in thousands):

	December 31,
	2017		2016
Deferred tax assets:
Net operating loss carryforwards	$	22,586	$	29,469
Inventory		1,520		1,187
Accruals		401		902
Depreciation and amortization		60		105
Other		1,228		1,312
Gross deferred tax assets		25,795		32,975
Valuation allowance		(25,721)		(32,850)
Deferred tax assets		74		125
Deferred tax liabilities:
Prepaid expenses		(74)		(125)
Deferred tax liabilities		(74)		(125)
Net deferred tax assets	$	—	$	—