Quarterly report pursuant to Section 13 or 15(d)

Stockholder's Equity - Additional Information (Detail)

v3.20.1
Stockholder's Equity - Additional Information (Detail) - USD ($)
$ / shares in Units, $ in Thousands
 3 Months Ended
Sep. 30, 2016
Mar. 31, 2020
Mar. 31, 2019
Dec. 31, 2019
Sep. 14, 2018
Schedule Of Capitalization Equity [Line Items]          
Common stock, par value (in dollars per share)   $ 0.001   $ 0.001  
Common stock, shares authorized (in shares)   250,000,000   250,000,000  
Common stock, shares issued (in shares)   97,876,042   97,413,721  
Common stock, shares outstanding (in shares)   97,876,042   97,413,721  
Derivative liability fair value adjustment   $ 700 $ (3,425)    
Warrant liabilities fair value adjustment   (4,768) 6,522    
Warrant liabilities   13,600      
Number of warrants issued to purchase common stock (in shares)         13,198,075
Warrants to purchase common stock associated with Loan Agreement          
Schedule Of Capitalization Equity [Line Items]          
Number of warrants issued to purchase common stock (in shares) 122,435        
Exercise price of warrants (in dollars per share) $ 3.6754        
Warrant expiration period 5 years        
Senior Convertible Note Purchase Agreement | Other (Income) Expense          
Schedule Of Capitalization Equity [Line Items]          
Derivative liability fair value adjustment   $ 700 $ 3,400