Balance Sheet Accounts - Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Sep. 30, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accrued R&D expenses	$ 18,106	$ 16,125
Accrued R&D expenses; co-development	11,104	5,895
Accrued capital expenditure	11,290	14,044
Other	6,104	3,699
Total accrued expense	$ 46,604	$ 39,763