Balance Sheet Accounts - Accrued Expenses (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Sep. 30, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accrued R&D expenses	$ 17,911	$ 16,125
Accrued R&D expenses; co-development	21,280	5,895
Accrued capital expenditures	6,909	14,044
Other	1,799	3,699
Total accrued expenses	$ 47,899	$ 39,763