Liability Related to the Sale of Future Royalties - Activity (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Liability, Sale Of Future Royalties [Roll Forward]
Beginning carrying value	$ 268,326	$ 0
Upfront payment received	0	250,000
Milestone payment received	50,000	0
Non-cash interest expense recognized	23,035	18,326	$ 0
Ending carrying value	$ 341,361	$ 268,326	$ 0