Condensed Consolidated Balance Sheets (Unaudited) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Current assets:
Cash and cash equivalents	$ 21,186	$ 9,941
Short-term investments	58,403	32,715
Accounts receivable, net	9,074	8,331
Inventory	6,407	6,750
Prepaid expenses and other	4,070	2,999
Total current assets	99,140	60,736
Restricted cash	143	201
Deferred offering costs		29
Property and equipment, net	5,050	3,065
Other assets	724	341
Total assets	105,057	64,372
Current liabilities:
Accounts payable	2,715	3,354
Accrued liabilities	7,038	7,088
Deferred revenue, current portion	3,601	1,462
Deferred rent, current portion	716	590
Long-term debt, current portion	160	6,136
Total current liabilities	14,230	18,630
Deferred revenue, net of current portion	3,774	803
Deferred rent, net of current portion	991	1,313
Long-term debt, net of current portion	20,208	12,157
Total liabilities	39,203	32,903
Commitment and contingencies
Stockholders' equity:
Preferred stock, $0.0001 par value, 15,000 shares authorized; none issued
Common stock, $0.0001 par value, 150,000 shares authorized; 18,101 and 14,620 shares issued and outstanding, respectively	2	1
Additional paid-in-capital	218,187	158,278
Other comprehensive income	7	22
Accumulated deficit	(152,342)	(126,832)
Total stockholders' equity	65,854	31,469
Total liabilities and stockholders' equity	$ 105,057	$ 64,372