Annual report pursuant to Section 13 and 15(d)

Fair Value Measurements - Fair Value of Financial Assets and Liabilities Measured on Recurring Basis (Details)

v3.20.4
Fair Value Measurements - Fair Value of Financial Assets and Liabilities Measured on Recurring Basis (Details) - Fair Value Measurements Recurring - USD ($)
$ in Thousands
Dec. 31, 2020
Dec. 31, 2019
Assets:    
Total $ 366,617 $ 131,664
Level 1    
Assets:    
Total 286,061 3,151
Level 2    
Assets:    
Total 80,556 128,513
Money Market Funds    
Assets:    
Total 204,632 3,151
Money Market Funds | Level 1    
Assets:    
Total 204,632 3,151
Commercial Paper    
Assets:    
Total 42,208 4,952
Commercial Paper | Level 2    
Assets:    
Total 42,208 4,952
Corporate Debt Securities    
Assets:    
Total 25,716 69,499
Corporate Debt Securities | Level 2    
Assets:    
Total 25,716 69,499
Equity Securities    
Assets:    
Total 41,644  
Equity Securities | Level 1    
Assets:    
Total 41,644  
Asset-backed Securities    
Assets:    
Total 12,632 27,055
Asset-backed Securities | Level 2    
Assets:    
Total 12,632 27,055
U.S. Government Securities    
Assets:    
Total 39,785 27,007
U.S. Government Securities | Level 1    
Assets:    
Total $ 39,785  
U.S. Government Securities | Level 2    
Assets:    
Total   $ 27,007