XML 69 R49.htm IDEA: XBRL DOCUMENT v3.20.4
Short-term Investments - Narrative (Details)
3 Months Ended 12 Months Ended
Dec. 31, 2020
USD ($)
investment
Sep. 30, 2020
USD ($)
Jun. 30, 2020
USD ($)
Mar. 31, 2020
USD ($)
Dec. 31, 2020
USD ($)
investment
Dec. 31, 2019
USD ($)
Dec. 31, 2018
USD ($)
Investments, Debt and Equity Securities [Abstract]              
Debt securities, available-for-sale, realized gain         $ 744,000 $ 594,000  
Debt securities, available-for-sale, realized gain         1,300,000 118,000  
Net unrealized gain on available-for-sale equity securities $ 1,070,975 $ 1,315,980 $ 4,358,634 $ (5,050,092) $ 1,695,497 $ 0 $ 0
Number of securities in a gross unrealized loss position | investment 12       12    
Number of securities in a gross unrealized loss position for more than twelve months | investment 0       0