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Stock-Based Compensation - Warrants (Details) - IPO - Warrants - USD ($)
12 Months Ended
Dec. 31, 2017
Dec. 31, 2019
Jul. 17, 2017
Jul. 16, 2017
Jul. 21, 2014
Stock-Based Compensation          
Warrants up to the number of shares, underwriters can purchase   0     201,600
Fair value of warrants         $ 611,000
Exercise price of IPO warrants (in dollars per share)     $ 2.42   $ 8.125
Exercise price expressed as a percent of original issue price         130.00%
Strike price (in dollars per share)     $ 10.05 $ 8.125  
Fair value modification of IPO warrants recognized $ 380,452        
Warrants exercised   162,031