Quarterly report pursuant to Section 13 or 15(d)

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

v3.21.1
Cash Equivalents and Investments (Schedule of Cash Equivalents and Available-for-Sale Securities) (Details) - USD ($)
Mar. 31, 2021
Dec. 31, 2020
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost $ 18,392,000 $ 18,387,000
Gross Unrealized Gains 7,000
Gross Unrealized Losses (3,000) (1,000)
Fair Value 18,389,000 18,393,000
Cash Equivalents 11,530,000 9,424,000
Short-Term Investments 693,424 2,759,024
Long-Term Investments 6,166,000 6,210,000
Cash Equivalents [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 11,530,000 9,424,000
Gross Unrealized Gains
Gross Unrealized Losses
Fair Value 11,530,000 9,424,000
Cash Equivalents 11,530,000 9,424,000
Short-Term Investments
Long-Term Investments
Cash Equivalents [Member] | Money Market Funds [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 11,530,000 9,424,000
Gross Unrealized Gains
Gross Unrealized Losses
Fair Value 11,530,000 9,424,000
Cash Equivalents 11,530,000 9,424,000
Short-Term Investments
Long-Term Investments
Investments [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 6,862,000 8,963,000
Gross Unrealized Gains 7,000
Gross Unrealized Losses (3,000) (1,000)
Fair Value 6,859,000 8,969,000
Cash Equivalents
Short-Term Investments 693,000 2,759,000
Long-Term Investments 6,166,000 6,210,000
Investments [Member] | Commercial Paper [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost   700,000
Gross Unrealized Gains  
Gross Unrealized Losses  
Fair Value   700,000
Cash Equivalents  
Short-Term Investments   700,000
Long-Term Investments  
Investments [Member] | Corporate Notes/Bonds [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 6,257,000 7,658,000
Gross Unrealized Gains 7,000
Gross Unrealized Losses (3,000) (1,000)
Fair Value 6,254,000 7,664,000
Cash Equivalents
Short-Term Investments 693,000 2,059,000
Long-Term Investments 5,561,000 5,605,000
Investments [Member] | Convertible Debt [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 605,000 605,000
Gross Unrealized Gains
Gross Unrealized Losses
Fair Value 605,000 605,000
Cash Equivalents
Short-Term Investments
Long-Term Investments $ 605,000 $ 605,000