Condensed Balance Sheets (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Current assets:
Cash and cash equivalents	$ 9,958	$ 17,807
Short-term investments	84,107	96,198
Prepaid and other current assets	3,958	3,177
Total current assets	98,023	117,182
Property and equipment, net	3,840	3,768
Intangibles, net	1,114	1,128
Other assets	1,038	987
Total assets	104,015	123,065
Current liabilities:
Accounts payable	2,642	1,172
Accrued liabilities	3,633	3,013
Accrued compensation	1,444	1,297
Current portion of deferred revenue	4,174	4,888
Total current liabilities	11,893	10,370
Convertible note payable, at fair value	10,665	11,279
Deferred revenue, less current portion	6,235	6,500
Other long-term liabilities	1,142	1,459
Total liabilities	29,935	29,608
Stockholders' equity:
Common stock, $0.001 par value; 200,000,000 shares authorized, 43,439,562 and 41,787,326 shares issued and outstanding at September 30, 2014 (unaudited) and December 31, 2013, respectively	43	42
Additional paid-in capital	187,702	172,518
Accumulated other comprehensive loss	(66)	(16)
Accumulated deficit	(113,599)	(79,087)
Total stockholders' equity	74,080	93,457
Total liabilities and stockholders' equity	$ 104,015	$ 123,065