Balance Sheet Accounts - Accrued Expenses (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Sep. 30, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accrued research and development expenses	$ 30,330	$ 28,069
Accrued research and development expenses; co-development	31,296	23,351
Accrued capital expenditures	277	4,206
Accrued income taxes (benefits)	20,799	0
Other	7,717	7,391
Total accrued expenses	$ 90,419	$ 63,017