Annual report pursuant to Section 13 and 15(d)

Fair Value Measurements - Schedule of Debt Securities Classified as Available-for-Sale Investments (Details)

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Fair Value Measurements - Schedule of Debt Securities Classified as Available-for-Sale Investments (Details) - USD ($)
Dec. 31, 2020
Dec. 31, 2019
Schedule Of Available For Sale Securities [Line Items]    
Amortized Cost $ 108,656,000  
Gross Unrealized Gains 6,000  
Fair value 108,662,000 $ 0
Money Market Funds Included in Cash and Cash Equivalents    
Schedule Of Available For Sale Securities [Line Items]    
Amortized Cost 101,429,000  
Fair value 101,429,000  
Corporate Bonds - due in One Year or Less    
Schedule Of Available For Sale Securities [Line Items]    
Amortized Cost 7,227,000  
Gross Unrealized Gains 6,000  
Fair value $ 7,233,000