Quarterly report pursuant to Section 13 or 15(d)

Cash Equivalents and Investments (Schedule of Estimated Fair Value of Available-for-Sale Securities) (Details)

v3.21.2
Cash Equivalents and Investments (Schedule of Estimated Fair Value of Available-for-Sale Securities) (Details) - USD ($)
$ in Thousands
Sep. 30, 2021
Dec. 31, 2020
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost $ 39,041 $ 18,387
Estimated Market Value 39,043 18,393
Investments [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost, Due within one year 2,860  
Amortized Cost, Due after one year through five years 3,043  
Amortized Cost 5,903 8,963
Estimated Market Value, Due within one year 2,861  
Estimated Market Value, Due after one year through five years 3,044  
Estimated Market Value $ 5,905 $ 8,969