Quarterly report pursuant to Section 13 or 15(d)

Organization and Principal Activities - Additional Information (Details)

v3.20.2
Organization and Principal Activities - Additional Information (Details)
$ / shares in Units, $ in Thousands
 3 Months Ended 9 Months Ended
May 14, 2020
USD ($)
$ / shares
shares
Sep. 30, 2020
USD ($)
shares
Jun. 30, 2020
shares
Sep. 30, 2020
USD ($)
Segment
Dec. 31, 2019
USD ($)
Organization Consolidation And Presentation Of Financial Statements [Line Items]          
Date of incorporation       Apr. 21, 2003  
Headquartered in       South San Francisco  
Headquartered in state       CA  
Number of operating segments | Segment       1  
Net proceeds from issuance of common stock       $ 108,250  
Accumulated deficit   $ 168,329   168,329 $ 195,745
Unrestricted cash, cash equivalents and marketable securities   202,400   $ 202,400  
Substantial doubt about going concern, within one year       false  
Minimum          
Organization Consolidation And Presentation Of Financial Statements [Line Items]          
Period from issuance date of unaudited interim condensed financial statements       1 year  
Common Stock          
Organization Consolidation And Presentation Of Financial Statements [Line Items]          
Shares of common stock | shares     12,650,000    
At-the-Market (“ATM")          
Organization Consolidation And Presentation Of Financial Statements [Line Items]          
Gross proceeds from issuance of common stock   17,400      
Underwriting discounts and commissions and other offering expenses   600      
Net proceeds from issuance of common stock   $ 16,800      
At-the-Market (“ATM") | Common Stock          
Organization Consolidation And Presentation Of Financial Statements [Line Items]          
Shares of common stock | shares   2,000,000      
Public Offering          
Organization Consolidation And Presentation Of Financial Statements [Line Items]          
Gross proceeds from issuance of common stock $ 98,000        
Underwriting discounts and commissions and other offering expenses 6,600        
Net proceeds from issuance of common stock $ 91,400        
Public Offering | Common Stock          
Organization Consolidation And Presentation Of Financial Statements [Line Items]          
Shares of common stock | shares 12,650,000        
Public offering price per share | $ / shares $ 7.75        
Underwriters’ Option to Purchase Shares | Common Stock          
Organization Consolidation And Presentation Of Financial Statements [Line Items]          
Shares of common stock | shares 1,650,000