Annual report pursuant to Section 13 and 15(d)

Basis of Presentation and Summary of Significant Accounting Policies - Additional Information (Details)

v3.20.4
Basis of Presentation and Summary of Significant Accounting Policies - Additional Information (Details)
 1 Months Ended 3 Months Ended 12 Months Ended
Aug. 31, 2018
USD ($)
Program
Dec. 31, 2020
USD ($)
$ / shares
Sep. 30, 2020
$ / shares
Jun. 30, 2020
$ / shares
Mar. 31, 2020
USD ($)
$ / shares
Dec. 31, 2020
USD ($)
$ / shares
Dec. 31, 2019
USD ($)
Dec. 31, 2018
USD ($)
Dec. 31, 2017
USD ($)
Jan. 01, 2019
USD ($)
Summary Of Significant Accounting Policies [Line Items]                    
Net loss           $ (32,128,000) $ (55,744,000) $ (35,317,000)    
Net income (loss) per share, basic | $ / shares   $ (1.48) $ 0.46 $ 1.00 $ (0.84)          
Net income (loss) per share, diluted | $ / shares   $ (1.48) $ 0.45 $ 0.94 $ (0.84)          
Restricted cash   $ 872,000       872,000 15,000 15,000    
Allowance for doubtful accounts receivable   0       0 0      
Impairment of long-lived assets to be disposed of           0 0      
Stockholders equity   $ 332,048,000       $ 332,048,000 97,789,000 131,539,000 $ (109,001,000)  
Deemed dividends             $ 0 0 $ 0  
Cumulative Effect Period of Adoption Adjustment                    
Summary Of Significant Accounting Policies [Line Items]                    
Stockholders equity               $ 10,327,000    
Cumulative Effect Period of Adoption Adjustment | Accounting Standards Update 2014-09                    
Summary Of Significant Accounting Policies [Line Items]                    
Stockholders equity                   $ 10,300,000
Minimum                    
Summary Of Significant Accounting Policies [Line Items]                    
Property and equipment useful lives           3 years        
Maximum                    
Summary Of Significant Accounting Policies [Line Items]                    
Property and equipment useful lives           5 years        
2018 Merck Agreement                    
Summary Of Significant Accounting Policies [Line Items]                    
Upfront payment received $ 60,000,000.0                  
Number of research programs | Program 2                  
Transaction price         $ 60,000,000.0          
Revenue recognized performance obligation         $ 47,100,000          
Number of target programs estimated service period         3 years          
Increase in revenue due to adjustments           $ 1,100,000        
Net loss           $ 1,100,000        
Net income (loss) per share, basic | $ / shares           $ 0.03        
Net income (loss) per share, diluted | $ / shares           $ 0.03