Quarterly report pursuant to Section 13 or 15(d)

Organization and Description of Business - Additional Information (Detail)

v3.19.1
Organization and Description of Business - Additional Information (Detail)
$ in Thousands
3 Months Ended
Mar. 31, 2019
USD ($)
Segment
Mar. 31, 2018
USD ($)
Dec. 31, 2018
USD ($)
Organization Consolidation And Presentation Of Financial Statements [Abstract]      
Number of operating segments | Segment 1    
Net loss $ (23,075) $ (17,005)  
Cash flows from operating activities (22,394) $ (6,441)  
Accumulated deficit (546,139)   $ (523,064)
Cash and cash equivalents and marketable securities $ 264,800