Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 15,256	$ 28,947
Restricted cash, current portion	1,092	901
Short-term investments	130,860	201,586
Accounts receivable, net of allowance of $1,890 in 2016 and $971 in 2015	13,396	5,862
Inventory	6,414	8,093
Prepaid expenses and other current assets	7,097	5,337
Total current assets	174,115	250,726
Property and equipment, net	32,289	12,710
Restricted cash, long term portion	342	683
Other assets	3,934	1,121
Total assets	210,680	265,240
Current liabilities:
Accounts payable	11,479	7,332
Accrued compensation	11,067	8,552
Other accrued liabilities	19,879	18,708
Deferred revenue	574	144
Short-term debt financing	49,624	42,090
Warrants	3,792	3,649
Total current liabilities	96,415	80,475
Deferred rent, net of current portion	7,789
Total liabilities	104,204	80,475
Commitments and contingencies (Note 6)
Stockholders' equity:
Preferred stock, $0.0001 par value: 50,000 shares authorized; no shares issued and outstanding at December 31, 2016 and 2015, respectively
Common stock, $0.0001 par value: 750,000 shares authorized at both December 31, 2016 and December 31, 2015, respectively; 52,665 and 50,346 shares issued and outstanding at December 31, 2016 and December 31, 2015, respectively	5	5
Additional paid in capital	453,044	436,259
Accumulated deficit	(345,848)	(250,083)
Accumulated other comprehensive loss	(725)	(1,416)
Total stockholders' equity	106,476	184,765
Total liabilities and stockholders' equity	$ 210,680	$ 265,240