Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 19,285	$ 33,636
Short-term investments	38,831	66,905
Accounts receivable, net of allowances of $3,625 and $284 at December 31, 2017 and 2016, respectively	22,244	17,447
Inventory	47,083	27,734
Prepaid expenses and other current assets	2,359	3,004
Total current assets	129,802	148,726
Property and equipment, net of accumulated depreciation of $13,587 and $10,227 at December 31, 2017 and 2016, respectively	18,110	14,929
Other non-current assets	241
Goodwill and other intangible assets, net	3,881	3,881
Total assets	152,034	167,536
Current liabilities:
Accounts payable	4,666	7,166
Accrued compensation and employee related benefits	5,729	7,647
Accrued liabilities	3,162	6,098
Current portion of long-term debt	4,088	2,589
Current portion of capital lease obligations	936	1,130
Current portion of deferred rent	628	306
Current portion of deferred revenue	714	445
Total current liabilities	19,923	25,381
Long-term debt, net of current portion	5,500	9,676
Capital lease obligations, net of current portion	745	1,698
Long-term liabilities — other	532	770
Deferred rent, net of current portion	5,891	5,022
Deferred revenue, net of current portion	501	966
Total liabilities	33,092	43,513
Stockholders' equity:
Preferred stock, $0.001 par value — 5,000 shares authorized, no shares issued and outstanding at December 31, 2017 and 2016, respectively
Common stock, $0.001 par value — 495,000 shares authorized, 20,973 and 20,336 shares issued and outstanding at December 31, 2017 and 2016, respectively	21	20
Additional paid-in capital	323,482	311,216
Accumulated other comprehensive income (loss)	(36)	(10)
Accumulated deficit	(204,525)	(187,203)
Total stockholders' equity	118,942	124,023
Total liabilities and stockholders' equity	$ 152,034	$ 167,536