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Stock-Based Compensation - Schedule of Assumptions Used to Determine Fair Value of Options Granted (Details)
6 Months Ended
Jun. 30, 2020
Jun. 30, 2019
Risk-free interest rate, minimum 0.71% 2.42%
Risk-free interest rate, maximum 1.33% 2.65%
Expected volatility, minimum 100.40% 101.30%
Expected volatility, maximum 104.20% 106.20%
Expected dividend yield 0.00% 0.00%
Minimum [Member]    
Expected life (in years) 8 years 6 months 7 years 6 months
Maximum [Member]    
Expected life (in years) 10 years 9 years 3 months 19 days