Quarterly report pursuant to Section 13 or 15(d)

Description of Business (Detail)

v3.19.2
Description of Business (Detail) - USD ($)
$ in Thousands
1 Months Ended 6 Months Ended
Jul. 31, 2019
Jun. 30, 2019
Jun. 30, 2018
Dec. 31, 2018
Organization And Description Of Business [Line Items]        
Entity incorporation state   Delaware    
Entity incorporation date   Aug. 01, 2012    
Accumulated Deficit   $ 667,570   $ 527,349
Proceeds from issuance of common stock through underwritten public offering, net   $ 7,630 $ 47,586  
Subsequent Event | Underwritten Public Offering        
Organization And Description Of Business [Line Items]        
Proceeds from issuance of common stock through underwritten public offering, net $ 140,600