Stock-Based Compensation - Stock options, fair value assumptions (Details) - USD ($) $ / shares in Units, $ in Millions	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Stock-Based Compensation
Fair value of options granted (in dollars per share)	$ 2.02	$ 5.88
Stock options
Stock-Based Compensation
Risk-free interest rate, minimum (as a percent)	3.57%	1.47%
Risk-free interest rate, maximum (as a percent)	4.40%	3.63%
Expected dividend yield (as a percent)	0.00%	0.00%
Expected volatility, minimum (as percentage)	81.69%	80.75%
Expected volatility, maximum (as percentage)	87.32%	87.64%
Unrecognized stock-based compensation expense	$ 14.3
Weighted-average period for unrecognized compensation expense to be recognized	2 years 3 months 18 days
Stock options | Minimum
Stock-Based Compensation
Expected term (in years)	5 years 6 months	5 years 3 months 7 days
Stock options | Maximum
Stock-Based Compensation
Expected term (in years)	6 years 29 days	6 years 29 days