Annual report pursuant to Section 13 and 15(d)

Stockholders' Equity - Additional Information (Detail)

v3.20.4
Stockholders' Equity - Additional Information (Detail) - USD ($)
$ / shares in Units, $ in Thousands
1 Months Ended 12 Months Ended
Aug. 07, 2020
Nov. 25, 2019
Sep. 25, 2018
Feb. 28, 2018
Feb. 27, 2018
Aug. 01, 2017
Jun. 23, 2017
Jul. 31, 2020
Dec. 31, 2017
Dec. 31, 2020
Dec. 31, 2019
Class Of Warrant Or Right [Line Items]                      
Net proceeds from common stock                   $ 48,372 $ 53,449
Preferred stock, par value                   $ 0.001 $ 0.001
Sale of securities $ 300,000                   $ 53,449
Term Loan Facility | Perceptive Credit Facility                      
Class Of Warrant Or Right [Line Items]                      
Warrant exercisable period         7 years            
Common stock exercise price         $ 9.5792            
Number of shares to be issued upon exercise of warrant         190,000            
Series A Convertible Preferred Stock                      
Class Of Warrant Or Right [Line Items]                      
Number of shares sold   250                  
Shares issued, price per share   $ 8.00                  
Preferred stock, conversion basis   Each share of Series A Preferred Stock is convertible to 1,000 shares of Common Stock, provided that the holder of Series A Preferred Stock will be prohibited from converting the Series A Preferred Stock into shares of common stock if, as a result of such conversion, the holder, together with its affiliates, would own more than 9.99% of the total number of shares of the Company’s common stock then issued and outstanding.                  
Number of preferred stock converted into common stock   1,000                  
Minimum holding percentage of common stock issued and outstanding upon conversion   9.99%                  
Preferred stock, par value   $ 0.001                  
Preferred Stock , voting rights description                   The Series A Preferred Stock has no voting rights, except as required by law and except that the consent of the Series A Preferred Stockholders will be required to amend the terms of the Series A Preferred Stock.  
Preferred stock beneficial conversion feature intrinsic value   $ 700                  
Common Stock                      
Class Of Warrant Or Right [Line Items]                      
Number of shares sold                     6,900,000
Sale of securities                     $ 7
Common Stock | Term Loan Facility | Perceptive Credit Facility                      
Class Of Warrant Or Right [Line Items]                      
Warrant exercisable period       7 years              
Common stock exercise price       $ 9.58              
Valuation of equity classified warrants recorded in additional paid-n capital       $ 1,500              
Expected dividend rate       0.00%              
Expected volatility       105.00%              
Risk free interest rate       2.80%              
Expected term       7 years              
Number of shares to be issued upon exercise of warrant       190,000              
Wedbush Agreement                      
Class Of Warrant Or Right [Line Items]                      
Valuation of equity classified warrants recorded in additional paid-n capital                 $ 400    
Expected dividend rate                 0.00%    
Expected volatility                 108.00%    
Risk free interest rate                 2.30%    
Expected term                 7 years    
Takeda Pharmaceuticals Inc                      
Class Of Warrant Or Right [Line Items]                      
Aggregate purchase price             $ 20,000        
Each unit of shares transaction of common stock             2,922,993        
Purchase price per share             $ 6.8423        
Vertex Pharmaceuticals Inc                      
Class Of Warrant Or Right [Line Items]                      
Aggregate purchase price             $ 15,000        
Each unit of shares transaction of common stock             1,666,666        
Purchase price per share             $ 9.00        
Private Placement                      
Class Of Warrant Or Right [Line Items]                      
Sale of securities                     $ 10,469
Private Placement | Common Stock                      
Class Of Warrant Or Right [Line Items]                      
Valuation of equity classified warrants recorded in additional paid-n capital           $ 16,300          
Expected dividend rate           0.00%          
Expected volatility           147.00%          
Risk free interest rate           2.07%          
Expected term           7 years          
Number of shares sold                     1,666,666
Sale of securities                     $ 2
Private Placement | Longitude Venture Partners III, L.P.                      
Class Of Warrant Or Right [Line Items]                      
Number of aggregate units sold           5,793,063          
Aggregate purchase price           $ 40,000          
Each unit of shares transaction of common stock           1          
Warrants to purchase shares of common stock           0.5          
Sale of units, description and its composition                   the Company sold an aggregate of 5,793,063 units (the “Units”) having an aggregate purchase price of $40.0 million (“PIPE Financing”), each such Unit consisting of (i) one (1) share (the “Shares”) of our common stock and (ii) a warrant (the “Private Placement Warrants”) to purchase 0.5 shares of our common stock (the “Private Placement”).  
Purchase price per unit           $ 6.9048          
Warrant exercisable period           7 years          
Common stock exercise price           $ 6.8423          
Private Placement | Longitude Venture Partners III, L.P. | Common Stock                      
Class Of Warrant Or Right [Line Items]                      
Warrants to purchase shares of common stock                   2,896,528  
Private Placement | Wedbush Agreement | Common Stock                      
Class Of Warrant Or Right [Line Items]                      
Warrants to purchase shares of common stock                 57,930 57,930  
Warrant exercisable period                 7 years    
Common stock exercise price                 $ 6.8423    
Underwritten Public Offering                      
Class Of Warrant Or Right [Line Items]                      
Number of shares sold     9,430,000                
Shares issued, price per share     $ 5.50                
Net proceeds from common stock     $ 48,100                
Over Allotment Option                      
Class Of Warrant Or Right [Line Items]                      
Number of shares sold   900,000 1,230,000                
2019 Underwritten Public Offering                      
Class Of Warrant Or Right [Line Items]                      
Number of shares sold   6,900,000                  
Shares issued, price per share   $ 8.00                  
Net proceeds from common stock   $ 53,400                  
At-the-market Sales (“ATM”)                      
Class Of Warrant Or Right [Line Items]                      
Net proceeds from common stock $ 100,000             $ 48,500      
Gross proceeds from common stock               $ 50,000      
Sale of securities                   $ 48,372  
At-the-market Sales (“ATM”) | Common Stock                      
Class Of Warrant Or Right [Line Items]                      
Number of shares sold                   4,133,916  
Sale of securities                   $ 4  
At-the-market Sales (“ATM”) | Common Stock at Purchase Price of $12.00 Per Share                      
Class Of Warrant Or Right [Line Items]                      
Purchase price per share               $ 12.00      
Number of shares sold               3,600,000      
At-the-market Sales (“ATM”) | Common Stock at Purchase Price of $12.70 Per Share                      
Class Of Warrant Or Right [Line Items]                      
Purchase price per share               $ 12.70      
Number of shares sold               500,000