Stock-Based Compensation - Schedule of Expenses Included in Operating Expenses (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total	$ 11,993	$ 14,711	$ 41,250	$ 48,984
Research and development
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total	6,898	6,221	21,008	21,634
General and administrative expense
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total	$ 5,095	$ 8,490	$ 20,242	$ 27,350