Quarterly report pursuant to Section 13 or 15(d)

Basis of Presentation and Summary of Significant Accounting Policies - Investment Categories (Details)

v3.21.2
Basis of Presentation and Summary of Significant Accounting Policies - Investment Categories (Details) - USD ($)
$ in Thousands
Jun. 30, 2021
Dec. 31, 2020
Debt Securities, Available-for-sale [Line Items]    
Amortized cost $ 239,039 $ 324,567
Gross unrealized gains 1,025 1,302
Gross unrealized losses (315) (1,391)
Estimated fair value 239,749 324,478
Estimated fair value 279,972 363,567
Bank deposits    
Debt Securities, Available-for-sale [Line Items]    
Amortized cost 33,560 84,120
Gross unrealized gains 13 35
Gross unrealized losses (2) (1)
Estimated fair value 33,571 84,154
Corporate bonds    
Debt Securities, Available-for-sale [Line Items]    
Amortized cost 25,965 30,512
Gross unrealized gains 62 99
Gross unrealized losses (2) (1)
Estimated fair value 26,025 30,610
Agency bonds    
Debt Securities, Available-for-sale [Line Items]    
Amortized cost 2,500 4,499
Gross unrealized gains 0 2
Gross unrealized losses (1) 0
Estimated fair value 2,499 4,501
Commercial paper    
Debt Securities, Available-for-sale [Line Items]    
Amortized cost 19,258 45,459
Gross unrealized gains 12 27
Gross unrealized losses 0 (1)
Estimated fair value 19,270 45,485
Corporate equity securities    
Debt Securities, Available-for-sale [Line Items]    
Amortized cost 5,807 4,466
Gross unrealized gains 172 360
Gross unrealized losses (310) (1,388)
Estimated fair value 5,669 3,438
Mutual fund    
Debt Securities, Available-for-sale [Line Items]    
Amortized cost 151,949 151,512
Gross unrealized gains 53 386
Gross unrealized losses 0 0
Estimated fair value 152,002 151,898
Treasury bill    
Debt Securities, Available-for-sale [Line Items]    
Amortized cost 0 3,999
Gross unrealized gains 0 0
Gross unrealized losses 0 0
Estimated fair value 0 3,999
Warrants    
Debt Securities, Available-for-sale [Line Items]    
Amortized cost 0 0
Gross unrealized gains 713 393
Gross unrealized losses 0 0
Estimated fair value 713 393
Estimated fair value 0 6,326
Common Stock    
Debt Securities, Available-for-sale [Line Items]    
Estimated fair value $ 40,223 $ 32,763