Fair Value Measurement - Summary of Company's Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2025	Sep. 30, 2024
Assets
U.S. government treasury bills	$ 46,710	$ 50,083
Total financial assets	215,104	249,941
U.S. government treasury bills
Assets
U.S. government treasury bills	46,710	50,083
Money market funds
Assets
Money market funds	168,394	199,858
Level 1
Assets
Total financial assets	215,104	249,941
Level 1 | U.S. government treasury bills
Assets
U.S. government treasury bills	46,710	50,083
Level 1 | Money market funds
Assets
Money market funds	168,394	199,858
Level 2
Assets
Total financial assets	0	0
Level 2 | U.S. government treasury bills
Assets
U.S. government treasury bills	0	0
Level 2 | Money market funds
Assets
Money market funds	0	0
Level 3
Assets
Total financial assets	0	0
Level 3 | U.S. government treasury bills
Assets
U.S. government treasury bills	0	0
Level 3 | Money market funds
Assets
Money market funds	$ 0	$ 0