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Stock-Based Compensation - Summary of Valuation Assumption to Estimate Fair Value of Stock Options (Details)
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Risk-free interest rate, Minimum 1.59% 2.60% 1.80%
Risk-free interest rate, Maximum 2.27% 3.00% 2.20%
Expected stock price volatility, Minimum 99.40% 87.40% 77.00%
Expected stock price volatility, Maximum 111.30% 92.60% 82.00%
Minimum      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Expected term of options (in years)     5 years 7 months 6 days
Maximum      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Expected term of options (in years) 6 years 1 month 6 days 6 years 1 month 6 days 6 years 8 months 12 days