Balance Sheet Accounts - Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Sep. 30, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accrued R&D expenses	$ 20,379	$ 28,069
Accrued R&D expenses; co-development	33,554	23,351
Accrued capital expenditures	2,574	4,206
Other	2,894	7,391
Total accrued expenses	$ 59,401	$ 63,017