Stockholders' Equity - Weighted-Average Key Assumptions and Fair Value Results for Shares Issued under ESPP (Details) - Employee Stock Purchase Plan - $ / shares	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected dividend yield	0.00%	0.00%	0.00%
Risk-free interest rate	5.33%	3.95%	0.41%
Expected volatility	50.45%	65.71%	69.58%
Expected life (in years)	6 months	6 months	6 months
Weighted-average fair value of shares issued (per share)	$ 6.69	$ 9.73	$ 27.54