License and Acquisition Agreements - Biogen Asset Purchase Agreement (Details) - USD ($) $ in Thousands	1 Months Ended			3 Months Ended
	Sep. 30, 2022	Sep. 30, 2017	Sep. 30, 2016	Mar. 31, 2024	Mar. 31, 2023
License and Acquisition Agreements
Uncured period which causes termination of the agreement, due to insolvency or bankruptcy or for material breach of the agreement by the other party that remains uncured		90 days
Notice period to terminate the agreement under payment-related breaches		30 days
Research and development				$ 26,334	$ 15,172
Maximum
License and Acquisition Agreements
Royalty rate increase (percentage)	1.00%
Asset Purchase Agreement | Biogen
License and Acquisition Agreements
Remaining milestone payments to be paid upon clinical and regulatory milestone achievement				165,000
Maximum aggregate obligation to pay insignificant annual maintenance fees as well as clinical and regulatory milestone payments			$ 1,575
Notice period to terminate the agreement			90 days
Uncured period which causes termination of the agreement, due to insolvency or bankruptcy or for material breach of the agreement by the other party that remains uncured			90 days
Notice period to terminate the agreement under payment-related breaches			30 days
Research and development				61	$ 0
Asset Purchase Agreement | Biogen | Maximum
License and Acquisition Agreements
Milestone payment to be paid upon clinical and regulatory milestone achievement				179,000
Milestone payment to be paid upon net sales milestone achievement				$ 150,000