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Cash, Cash Equivalent, and Investments (Details) - USD ($)
 3 Months Ended 12 Months Ended
Mar. 31, 2019
Mar. 31, 2018
Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Cash and Cash Equivalents $ 3,975,761   $ 2,386,314
Short term investments, adjusted cost 35,778,093   38,816,441
Cash and Investment, fair value 39,745,932   41,117,434
Investment, gross unrealized holding gain 0   0
Investment, gross unrealized holding losses (7,922)   (85,321)
Cash and Investment, adjusted cost 39,753,854   41,202,755
Cash      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Cash and Cash Equivalents 675,229   1,048,272
Money Market Funds | Level 1      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Cash and Cash Equivalents 3,300,532   1,338,042
Corporate bonds      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Held-to-maturity, premium paid on purchase 80,855 $ 286,999 378,681
Corporate bonds | Level 2      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Short term investments, fair value 35,770,171   38,731,120
Short term investments, gross unrealized holding gain 0   0
Short term investments, gross unrealized holding loss (7,922)   (85,321)
Short term investments, adjusted cost 35,778,093   38,816,441
Long term Investments, fair value 0   0
Long term Investments, gross unrealized holding gain 0   0
Long term Investments, gross unrealized holding loss 0   0
Long term investments, adjusted cost $ 0   $ 0