Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 15,737	$ 17,223
Short-term investments	36,784	55,002
Accounts receivable, net	13,217	12,436
Inventory	9,410	5,444
Prepaid expenses and other	6,310	5,242
Total current assets	81,458	95,347
Restricted cash	143	143
Deferred offering costs	137
Property and equipment, net	7,229	6,366
Other assets	823	892
Total assets	89,790	102,748
Current liabilities:
Accounts payable	2,386	3,380
Accrued liabilities	7,287	10,403
Deferred revenue, current portion	5,678	4,627
Deferred rent, current portion	297	147
Long-term debt, current portion	271	251
Total current liabilities	15,919	18,808
Deferred revenue, net of current portion	6,806	7,135
Deferred rent, net of current portion	1,995	1,317
Long-term debt, net of current portion	31,106	30,675
Total liabilities	$ 55,826	$ 57,935
Commitment and contingencies
Stockholders' equity:
Preferred stock, $0.0001 par value, 15,000 shares authorized; none issued	$ 0	$ 0
Common stock, $0.0001 par value, 150,000 shares authorized; 19,386 and 18,272 shares issued and outstanding at June 30, 2015 and December 31, 2014, respectively	2	2
Additional paid-in-capital	238,159	221,724
Accumulated other comprehensive loss	(29)	(43)
Accumulated deficit	(204,168)	(176,870)
Total stockholders' equity	33,964	44,813
Total liabilities and stockholders' equity	$ 89,790	$ 102,748