v3.19.3.a.u2
Stock-Based Compensation - Schedule of Assumptions Used in Black-Scholes Option-Pricing Method (Details) - $ / shares
3 Months Ended 9 Months Ended 12 Months Ended
Sep. 30, 2019
Sep. 30, 2018
Sep. 30, 2019
Sep. 30, 2018
Dec. 31, 2018
Dec. 31, 2017
Expected dividend yield 0.00% 0.00% 0.00% 0.00% 0.00% 0.00%
Expected stock-price volatility, minimum 69.00% 48.89% 46.33% 46.47% 46.47% 53.08%
Expected stock-price volatility, maximum 69.38% 50.22% 69.38% 53.11% 53.11% 54.08%
Risk-free interest rate, minimum 1.47% 2.78% 1.47% 2.46% 2.46% 1.89%
Risk-free interest rate, maximum 1.54% 3.07% 2.60% 3.07% 3.07% 2.58%
Expected average term of options           10 years
Stock price $ 1.04          
Minimum [Member]            
Expected average term of options 5 years 7 years 5 years 5 years 5 years  
Stock price   $ 1.85 $ 0.60 $ 1.85 $ 1.85 $ 0.30
Maximum [Member]            
Expected average term of options 7 years 10 years 7 years 10 years 10 years  
Stock price   $ 2.22 $ 1.04 $ 3.40 $ 3.40 $ 3.48