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Stockholders' Equity - Schedule of Assumptions Used in Black-Scholes Model Pricing Model to to Determine Fair Value of Stock Option and Shares Purchasable Under ESPP (Details)
3 Months Ended
Mar. 31, 2021
Mar. 31, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]    
Risk-free interest rate   1.50%
Risk-free interest rate, Minimum 0.50%  
Risk-free interest rate, Maximum 1.10%  
Expected volatility 88.00% 88.00%
Expected dividend yield 0.00% 0.00%
Minimum    
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]    
Expected term (in years) 5 years 9 months 18 days 6 years
Maximum    
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]    
Expected term (in years) 6 years 1 month 6 days 6 years 1 month 6 days