Quarterly report pursuant to Section 13 or 15(d)

Summary of Significant Accounting Policies - Additional Information (Details)

v3.20.2
Summary of Significant Accounting Policies - Additional Information (Details)
$ / shares in Units, $ in Thousands
 1 Months Ended 3 Months Ended 6 Months Ended
Aug. 31, 2018
USD ($)
Program
Jun. 30, 2020
$ / shares
Mar. 31, 2020
USD ($)
Jun. 30, 2019
$ / shares
Jun. 30, 2020
USD ($)
$ / shares
Jun. 30, 2019
USD ($)
$ / shares
Jun. 16, 2020
Summary Of Significant Accounting Policies [Line Items]              
Net income         $ (10,277) $ 28,043  
Net income (loss) per share, basic | $ / shares [1]   $ 1.00   $ (0.60) $ 0.39 $ (1.22)  
Net income (loss) per share, diluted | $ / shares [1]   $ 0.94   $ (0.60) $ 0.36 $ (1.22)  
Fair Value Measurements Recurring | Level 2 | Measurement Input Discount for Lack of Marketability              
Summary Of Significant Accounting Policies [Line Items]              
Alternative investment, measurement input             5.4
2018 Merck Agreement              
Summary Of Significant Accounting Policies [Line Items]              
Upfront payment received $ 60,000            
Number of research programs | Program 2            
Transaction price     $ 60,000        
Revenue recognized performance obligation     $ 47,100        
Number of target programs estimated service period     3 years        
Decrease in revenue due to adjustments         $ 3,600    
Net income         $ 3,600    
Net income (loss) per share, basic | $ / shares         $ 0.14    
Net income (loss) per share, diluted | $ / shares         $ 0.13    
[1] See Notes 2 and 10 for an explanation of the calculations of our basic and diluted net income (loss) per share, basic and diluted and the weighted-average number of shares used in the computation of the per share amounts.