Annual report pursuant to Section 13 and 15(d)

Financial instruments - Fair value of assets and liabilities (Details)

v3.20.4
Financial instruments - Fair value of assets and liabilities (Details) - USD ($)
$ in Thousands
Dec. 31, 2020
Dec. 31, 2019
Marketable securities:    
Marketable securities $ 311,335 $ 39,130
Recurring basis    
Marketable securities:    
Marketable securities 311,335 39,130
Recurring basis | Level 1    
Marketable securities:    
Marketable securities 305,334 39,130
Recurring basis | Level 2    
Marketable securities:    
Marketable securities 6,001  
Corporate debt securities | Recurring basis    
Marketable securities:    
Marketable securities 305,334 39,130
Corporate debt securities | Recurring basis | Level 1    
Marketable securities:    
Marketable securities 305,334 $ 39,130
Agency bond | Recurring basis    
Marketable securities:    
Marketable securities 6,001  
Agency bond | Recurring basis | Level 2    
Marketable securities:    
Marketable securities $ 6,001