Stock-Based Compensation - Stock options, fair value assumptions (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Stock-Based Compensation
Fair value of options granted (in dollars per share)	$ 2.02	$ 5.58
Maximum
Stock-Based Compensation
Aggregate intrinsic value of options exercised (in dollars)	$ 0.1	$ 0.1
Employee Stock Option
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%	4.22%
Expected dividend yield (as a percent)	0.00%	0.00%
Expected volatility, minimum (as percentage)	81.70%	80.80%
Expected volatility, maximum (as percentage)	87.30%	87.60%
Unrecognized stock-based compensation expense	$ 12.5
Weighted-average period for unrecognized compensation expense to be recognized	2 years
Employee Stock Option | Minimum
Stock-Based Compensation
Expected term (in years)	5 years 6 months	5 years 3 months 18 days
Employee Stock Option | Maximum
Stock-Based Compensation
Expected term (in years)	6 years 1 month 6 days	6 years 1 month 6 days