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Stock Based Compensation - Key Assumptions Used for Black-Scholes Option-pricing Model to Estimate the Fair Value of Stock Options (Details)
6 Months Ended
Jun. 30, 2021
Jun. 30, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]    
Risk free interest rate 0.67% 1.10%
Expected term (in years) 6 years 25 days 6 years 21 days
Expected dividend yield 0.00% 0.00%
Expected volatility of underlying common stock 73.00% 71.00%