Stock-Based Compensation - Assumptions (Details)	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
OnkosXcel PSUs
Stock-Based Compensation
Expected term	5 years 9 months 18 days
Expected stock price volatility (as a percent)	97.40%
Risk-free rate of interest (as a percent)	3.60%
Expected dividend yield (as a percent)	0.00%
Stock options
Stock-Based Compensation
Expected stock price volatility, minimum (as a percent)	96.60%	92.70%
Expected stock price volatility, maximum (as a percent)	109.20%	96.90%
Risk-free rate of interest, minimum (as a percent)	3.50%	1.50%
Risk-free rate of interest, maximum (as a percent)	4.40%	3.60%
Expected dividend yield (as a percent)	0.00%
Stock options | Minimum
Stock-Based Compensation
Expected term	5 years 6 months	5 years 6 months
Expected dividend yield (as a percent)	0.00%	0.00%
Stock options | Maximum
Stock-Based Compensation
Expected term	6 years 1 month 6 days	6 years 1 month 6 days
Expected dividend yield (as a percent)	0.00%	0.00%