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
Jun. 30, 2021
Dec. 31, 2020
Schedule of Available-for-sale Securities [Line Items]    
Estimated Market Value $ 18,166 $ 18,393
Investments [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost, Due within one year 1,705  
Amortized Cost, Due after one year through five years 4,897  
Amortized Cost 6,602  
Estimated Market Value, Due within one year 1,705  
Estimated Market Value, Due after one year through five years 4,897  
Estimated Market Value $ 6,602 $ 8,969