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Stock-Based Compensation - Summary of Stock Option Activity (Details) - 2002 Plan and 2018 Plan - USD ($)
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Total Options, Outstanding at December 31, 2016 1,075,209 1,001,546  
Total Options, Granted 563,268 99,866  
Total Options, Exercised (43,687) (2,547)  
Total Options, Cancelled or expired (49,387) (23,656)  
Total Options, Outstanding at December 31, 2018 1,545,403 1,075,209 1,001,546
Total Options, Vested and expected to vest at December 31, 2018 1,545,403    
Total Options, Vested and exercisable at December 31, 2018 801,294    
Weighted- Average Exercise Price Per Share, Outstanding at December 31, 2016 $ 1.60 $ 1.62  
Weighted- Average Exercise Price Per Share, Granted 4.07 1.44  
Weighted- Average Exercise Price Per Share, Exercised 2.12 1.20  
Weighted- Average Exercise Price Per Share, Cancelled or expired 1.65 1.76  
Weighted- Average Exercise Price Per Share, Outstanding at December 31, 2018 2.48 $ 1.60 $ 1.62
Weighted- Average Exercise Price Per Share, Vested and expected to vest at December 31, 2018 2.48    
Weighted- Average Exercise Price Per Share, Vested and exercisable at December 31, 2018 $ 1.65    
Weighted- Average Remaining Contractual Term (in years), Outstanding Balance 7 years 7 months 6 days 7 years 3 months 18 days 8 years 1 month 6 days
Weighted- Average Remaining Contractual Term (in years), Vested and expected to vest at December 31, 2018 7 years 7 months 6 days    
Weighted- Average Remaining Contractual Term (in years), Vested and exercisable at December 31, 2018 6 years 3 months 18 days    
Aggregate Intrinsic Value, Outstanding $ 1,593,487 $ 711,328 $ 58,619
Aggregate Intrinsic Value, Vested and expected to vest at December 31, 2018 1,593,487    
Aggregate Intrinsic Value, Vested and exercisable at December 31, 2018 $ 1,175,200