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Short-term Investments - Narrative (Details)
3 Months Ended 6 Months Ended
Jun. 30, 2020
USD ($)
investment
Jun. 30, 2019
USD ($)
Jun. 30, 2020
USD ($)
investment
Jun. 30, 2019
USD ($)
Investments, Debt and Equity Securities [Abstract]        
Realized gain on investments $ 585,000 $ 157,000 $ 635,000 $ 175,000
Realized loss on investments 686,000 29,000 1,200,000 82,000
Net unrealized gain (loss) on available-for-sale equity securities $ 4,358,634 $ 0 $ (691,458) $ 0
Number of securities in a gross unrealized loss position | investment 16   16  
Number of securities in a gross unrealized loss position for more than twelve months | investment 0   0