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Cash and Cash Equivalents (Details Textual) - USD ($)
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Cash and Cash Equivalents (Textual)      
Debt covenant, description Debt covenant to maintain at least $2,000,000 of otherwise unrestricted cash, cash equivalents and short-term investments.    
Cash and cash equivalents $ 2,521,050 $ 3,798,811 $ 5,150,344