Organization and Description of Business (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accumulated deficit	$ 1,319,578	$ 1,241,908
Net loss attributable to common stockholders	77,670	208,726	$ 204,618
Cash and cash equivalents	183,049	226,316
Short-term investments	$ 49,385	$ 50,083