Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 7,138	$ 15,256
Restricted cash, current portion	764	1,092
Short-term investments	94,988	130,860
Accounts receivable, net of allowance of $1,648 in 2017 and $1,890 in 2016	7,107	13,396
Inventory	7,359	6,414
Prepaid expenses and other current assets	5,748	7,097
Total current assets	123,104	174,115
Property and equipment, net	31,268	32,289
Restricted cash, long term portion	342	342
Other assets	3,711	3,934
Total assets	158,425	210,680
Current liabilities:
Accounts payable	10,389	11,479
Accrued compensation	8,106	11,067
Other accrued liabilities	25,612	19,879
Deferred revenue	669	574
Short-term debt financing	50,022	49,624
Warrants	3,472	3,792
Total current liabilities	98,270	96,415
Deferred rent, net of current portion	9,247	7,789
Total liabilities	107,517	104,204
Commitments and contingencies (Note 6)
Stockholders' equity:
Common stock, $0.0001 par value: 750,000 shares authorized at both June 30, 2017 and December 31, 2016, respectively; 53,208 and 52,665 shares issued and outstanding at June 30, 2017 and December 31, 2016, respectively	6	5
Additional paid in capital	460,906	453,044
Accumulated deficit	(409,541)	(345,848)
Accumulated other comprehensive loss	(463)	(725)
Total stockholders' equity	50,908	106,476
Total liabilities and stockholders' equity	$ 158,425	$ 210,680