Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 21,856	$ 17,223
Short-term investments	27,188	55,002
Accounts receivable, net	19,725	12,436
Inventory	10,138	5,444
Prepaid expenses and other current assets	3,886	5,114
Total current assets	82,793	95,219
Restricted cash	143	143
Deferred offering costs	181	0
Property and equipment, net	9,414	6,366
Other assets	338	340
Total assets	92,869	102,068
Current liabilities:
Accounts payable	3,243	3,380
Accrued liabilities	12,181	10,403
Deferred revenue, current portion	5,261	4,627
Deferred rent, current portion		147
Lease financing obligations, current portion	226	251
Total current liabilities	20,911	18,808
Deferred revenue, net of current portion	6,486	7,135
Deferred rent, net of current portion	4,257	1,317
Long-term debt and lease financing obligations, net of current portion and debt issuance costs	41,000	29,995
Total liabilities	$ 72,654	$ 57,255
Commitments and contingencies (Note 15)
Stockholders' equity
Preferred stock, $0.0001 par value, 15,000 shares authorized; none issued
Common stock, $0.0001 par value, 150,000 shares authorized; 19,570 and 18,272 shares issued and outstanding at December 31, 2015 and 2014, respectively	$ 2	$ 2
Additional paid-in-capital	242,693	221,724
Other comprehensive loss	(29)	(43)
Accumulated deficit	(222,451)	(176,870)
Total stockholders' equity	20,215	44,813
Total liabilities and stockholders' equity	$ 92,869	$ 102,068