Quarterly report pursuant to Section 13 or 15(d)

Organization and Description of Business - Additional Information (Detail)

v3.5.0.2
Organization and Description of Business - Additional Information (Detail) - USD ($)
$ in Thousands
3 Months Ended 6 Months Ended
Jun. 30, 2016
Jun. 30, 2015
Jun. 30, 2016
Jun. 30, 2015
Dec. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]          
Net loss $ (6,992) $ (1,357) $ (13,840) $ (3,685)  
Cash flows from operating activities     (12,210) $ (11,468)  
Accumulated deficit (410,128)   (410,128)   $ (396,288)
Cash and cash equivalents and marketable securities $ 29,100   $ 29,100