Annual report pursuant to Section 13 and 15(d)

Balance Sheet Account Details - Investment Categories (Details)

v3.20.4
Balance Sheet Account Details - Investment Categories (Details) - USD ($)
$ in Thousands
Dec. 31, 2020
Dec. 31, 2019
Short-term investments    
Debt Securities, Available-for-sale [Line Items]    
Cost $ 324,567 $ 941,175
Gross unrealized gains 1,302 933
Gross unrealized losses (1,391) (2,118)
Estimated fair value 324,478 939,990
Mutual fund    
Debt Securities, Available-for-sale [Line Items]    
Cost 151,512 250,636
Gross unrealized gains 386 0
Gross unrealized losses 0 (249)
Estimated fair value 151,898 250,387
Bank deposits    
Debt Securities, Available-for-sale [Line Items]    
Cost 84,120 411,690
Gross unrealized gains 35 188
Gross unrealized losses (1) (3)
Estimated fair value 84,154 411,875
Commercial paper    
Debt Securities, Available-for-sale [Line Items]    
Cost 45,459 210,525
Gross unrealized gains 27 43
Gross unrealized losses (1) (16)
Estimated fair value 45,485 210,552
Corporate bonds    
Debt Securities, Available-for-sale [Line Items]    
Cost 30,512 63,818
Gross unrealized gains 99 161
Gross unrealized losses (1) 0
Estimated fair value 30,610 63,979
Agency bonds    
Debt Securities, Available-for-sale [Line Items]    
Cost 4,499  
Gross unrealized gains 2  
Gross unrealized losses 0  
Estimated fair value 4,501  
Corporate equity securities    
Debt Securities, Available-for-sale [Line Items]    
Cost 4,466 4,506
Gross unrealized gains 360 416
Gross unrealized losses (1,388) (1,850)
Estimated fair value 3,438 3,072
Treasury bill    
Debt Securities, Available-for-sale [Line Items]    
Cost 3,999  
Gross unrealized gains 0  
Gross unrealized losses 0  
Estimated fair value 3,999  
Warrants    
Debt Securities, Available-for-sale [Line Items]    
Cost 0 0
Gross unrealized gains 393 125
Gross unrealized losses 0 0
Estimated fair value $ 393 $ 125