Commitments and Contingencies - Narratives (Details) - USD ($) $ in Thousands	1 Months Ended	9 Months Ended	12 Months Ended
	Mar. 31, 2023	Sep. 30, 2023	Dec. 31, 2021
Commitments and Contingencies
Financing liability		$ 1,000
Accrued settlement		200
Penn License Agreement | Penn
Commitments and Contingencies
Annual payments to be made		25,000	$ 10,000
Additional milestone payments for first CAR-M product		1,700
Penn License Agreement | Penn | Maximum
Commitments and Contingencies
Milestone payments		10,900
Additional milestone payments		30,000
Novartis Agreement
Commitments and Contingencies
Agreement term	5 years
Renewal term	1 year
Amount payable per calendar year for reserved capacity	$ 1,000
Termination fee payable	$ 4,000
Lab Equipment
Commitments and Contingencies
Financing liability		$ 2,100