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Stock Based Compensation - Stock Option Valuation (Details) - Stock options to purchase common stock
3 Months Ended
Mar. 31, 2022
Mar. 31, 2021
Assumptions used to determine the fair value of stock options granted    
Risk‑free interest rate 1.61% 0.63%
Expected volatility 70.00% 76.00%
Expected dividend yield 0.00% 0.00%
Expected term (in years) 6 years 21 days 6 years 14 days