Quarterly report pursuant to Section 13 or 15(d)

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

v3.20.2
Basis of Presentation and Summary of Significant Accounting Policies - Investment Categories (Details) - USD ($)
$ in Thousands
Jun. 30, 2020
Dec. 31, 2019
Equity Securities, FV-NI [Abstract]    
Estimated fair value $ 8,816 $ 9,910
Debt and Equity Securities, FV-NI [Abstract]    
Amortized cost 643,813 941,174
Gross unrealized gains 1,291 933
Gross unrealized losses (2,731) (2,118)
Estimated fair value 642,373 939,989
Bank deposits    
Debt Securities, Available-for-sale [Line Items]    
Amortized cost 269,114 411,690
Gross unrealized gains 221 188
Gross unrealized losses (56) (3)
Estimated fair value 269,279 411,875
Corporate bonds    
Debt Securities, Available-for-sale [Line Items]    
Amortized cost 55,380 63,818
Gross unrealized gains 125 161
Gross unrealized losses (94) 0
Estimated fair value 55,411 63,979
Commercial paper    
Debt Securities, Available-for-sale [Line Items]    
Amortized cost 163,590 210,525
Gross unrealized gains 134 43
Gross unrealized losses 0 (16)
Estimated fair value 163,724 210,552
Corporate equity securities    
Debt Securities, Available-for-sale [Line Items]    
Amortized cost 4,506 4,506
Gross unrealized gains 634 416
Gross unrealized losses (2,484) (1,850)
Estimated fair value 2,656 3,072
Mutual fund    
Debt Securities, Available-for-sale [Line Items]    
Amortized cost 151,223 250,635
Gross unrealized gains 0 0
Gross unrealized losses (97) (249)
Estimated fair value 151,126 250,386
Warrants    
Equity Securities, FV-NI [Abstract]    
Amortized cost 0 0
Gross unrealized gains 177 125
Gross unrealized losses 0 0
Estimated fair value $ 177 $ 125