Quarterly report pursuant to Section 13 or 15(d)

Cash Equivalents and Investments (Narrative) (Details)

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Cash Equivalents and Investments (Narrative) (Details) - USD ($)
1 Months Ended 3 Months Ended
Apr. 30, 2020
Mar. 31, 2021
Mar. 31, 2020
Debt and Equity Securities, FV-NI [Line Items]      
Gross realized gains (losses)   $ 0 $ 0
Common Stock [Member]      
Debt and Equity Securities, FV-NI [Line Items]      
Investment $ 899,000    
Maximum [Member] | Common Stock [Member]      
Debt and Equity Securities, FV-NI [Line Items]      
Minority investment, ownership percentage 10.00%