Condensed Consolidated Balance Sheets (Unaudited) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Current assets:
Cash and cash equivalents	$ 18,826	$ 9,941
Short-term investments	48,674	32,715
Accounts receivable, net	15,266	8,331
Inventory	5,790	6,750
Prepaid expenses and other	4,353	2,999
Total current assets	92,909	60,736
Restricted cash	143	201
Deferred offering costs	0	29
Property and equipment, net	5,746	3,065
Other assets	735	341
Total assets	99,533	64,372
Current liabilities:
Accounts payable	2,166	3,354
Accrued liabilities	7,755	7,088
Deferred revenue, current portion	4,425	1,462
Deferred rent, current portion	807	590
Long-term debt, current portion	251	6,136
Total current liabilities	15,404	18,630
Deferred revenue, net of current portion	7,168	803
Deferred rent, net of current portion	784	1,313
Long-term debt, net of current portion	20,497	12,157
Total liabilities	43,853	32,903
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; 18,201 and 14,620 shares issued and outstanding at September 30, 2014 and December 31, 2013, respectively	2	1
Additional paid-in-capital	220,190	158,278
Other comprehensive income (loss)	(21)	22
Accumulated deficit	(164,491)	(126,832)
Total stockholders' equity	55,680	31,469
Total liabilities and stockholders' equity	$ 99,533	$ 64,372