Quarterly report pursuant to Section 13 or 15(d)

Organization and Description of Business - Additional Information (Detail)

v3.10.0.1
Organization and Description of Business - Additional Information (Detail)
$ in Thousands
3 Months Ended 5 Months Ended 6 Months Ended
Jun. 04, 2018
USD ($)
Jun. 30, 2018
USD ($)
Jun. 30, 2017
USD ($)
Jun. 01, 2018
USD ($)
Jun. 30, 2018
USD ($)
Segment
Jun. 30, 2017
USD ($)
Dec. 31, 2017
USD ($)
Organization And Description Of Business [Line Items]              
Number of operating segments | Segment         1    
Net loss   $ (17,531) $ (8,929)   $ (34,536) $ (14,280)  
Cash flows from operating activities         (19,264) (8,094)  
Accumulated deficit   (485,052)     (485,052)   $ (450,516)
Repayment of facility loan         6,527 $ 1,534  
Cash and cash equivalents and marketable securities   $ 212,100     $ 212,100    
2015 Term Loan Facility [Member]              
Organization And Description Of Business [Line Items]              
Principal payments       $ 1,600      
Repayment of facility loan $ 4,200            
Facility loan, final fee $ 700