Quarterly report pursuant to Section 13 or 15(d)

Marketable securities - Available-for-sale debt securities (Details)

v3.21.1
Marketable securities - Available-for-sale debt securities (Details)
$ in Thousands
3 Months Ended
Mar. 31, 2021
USD ($)
Debt Securities  
Marketable securities  
Amortized cost $ 285,626
Gross unrealized gains 109
Gross unrealized losses (223)
Aggregate estimated fair value 285,512
Corporate Debt Securities Maturity Period Less Than Three Months | Debt Securities  
Marketable securities  
Amortized cost 54,372
Gross unrealized gains 15
Gross unrealized losses (11)
Aggregate estimated fair value 54,376
Corporate Debt Securities Maturity Period Three Months To One Year  
Marketable securities  
Amortized cost 114,136
Gross unrealized gains 35
Gross unrealized losses (39)
Aggregate estimated fair value 114,132
Corporate Debt Securities Maturity Period One Year To Two Years | Debt Securities  
Marketable securities  
Amortized cost 111,119
Gross unrealized gains 53
Gross unrealized losses (173)
Aggregate estimated fair value 110,999
Agency Bond Maturity Period One Year To Two Years | Marketable securities  
Marketable securities  
Amortized cost 5,999
Gross unrealized gains 6
Aggregate estimated fair value $ 6,005
Minimum | Corporate Debt Securities Maturity Period One Year or Less | Debt Securities  
Marketable securities  
Available For Sale Securities Debt Maturity Period 3 months
Minimum | Corporate Debt Securities Maturity Period One Year To Two Years | Debt Securities  
Marketable securities  
Available For Sale Securities Debt Maturity Period 1 year
Minimum | Agency Bond Maturity Period One Year To Two Years | Marketable securities  
Marketable securities  
Available For Sale Securities Debt Maturity Period 1 year
Maximum | Corporate Debt Securities Maturity Period Less Than Three Months | Debt Securities  
Marketable securities  
Available For Sale Securities Debt Maturity Period 3 months
Maximum | Corporate Debt Securities Maturity Period One Year or Less | Debt Securities  
Marketable securities  
Available For Sale Securities Debt Maturity Period 1 year
Maximum | Corporate Debt Securities Maturity Period One Year To Two Years | Debt Securities  
Marketable securities  
Available For Sale Securities Debt Maturity Period 2 years
Maximum | Agency Bond Maturity Period One Year To Two Years | Marketable securities  
Marketable securities  
Available For Sale Securities Debt Maturity Period 2 years