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Stock-Based Compensation - Option Pricing Assumptions (Details)
9 Months Ended
Sep. 30, 2020
Sep. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Expected dividend yield 0.00% 0.00%
Expected term 6 years 3 months 6 years 3 months
Minimum    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Expected volatility 67.30% 73.70%
Risk-free interest rate 0.40% 1.40%
Maximum    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Expected volatility 109.00% 76.60%
Risk-free interest rate 1.80% 2.60%