Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 9,086	$ 15,256
Restricted cash, current portion	775	1,092
Short-term investments	106,692	130,860
Accounts receivable, net of allowance of $1,789 in 2017 and $1,890 in 2016	7,478	13,396
Inventory	8,223	6,414
Prepaid expenses and other current assets	7,907	7,097
Total current assets	140,161	174,115
Property and equipment, net	31,752	32,289
Restricted cash, long term portion	342	342
Other assets	3,769	3,934
Total assets	176,024	210,680
Current liabilities:
Accounts payable	6,610	11,479
Accrued compensation	9,328	11,067
Other accrued liabilities	23,928	19,879
Deferred revenue	592	574
Short-term debt financing	49,807	49,624
Warrants	2,750	3,792
Total current liabilities	93,015	96,415
Deferred rent, net of current portion	9,337	7,789
Total liabilities	102,352	104,204
Commitments and contingencies (Note 6)
Stockholders' equity:
Common stock, $0.0001 par value: 750,000 shares authorized at both March 31, 2017 and December 31, 2016, respectively; 52,808 and 52,665 shares issued and outstanding at March 31, 2017 and December 31, 2016, respectively	6	5
Additional paid in capital	456,000	453,044
Accumulated deficit	(381,809)	(345,848)
Accumulated other comprehensive loss	(525)	(725)
Total stockholders' equity	73,672	106,476
Total liabilities and stockholders' equity	$ 176,024	$ 210,680