Income Taxes - Summary of Effective Income Tax Rate Reconciliation (Details)	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Income Tax Disclosure [Abstract]
U.S. federal statutory income tax	21.00%	21.00%	21.00%
State income taxes, net of federal tax benefit	2.60%	0.40%	8.60%
Tax credits	3.00%	6.80%	0.00%
Permanent and other items	2.50%	(4.60%)	(1.70%)
Non-deductible compensation	(0.90%)	(4.60%)	0.00%
Foreign-derived intangible income deduction	0.00%	1.20%	0.00%
Stock compensation	(0.70%)	(1.10%)	(1.70%)
Valuation allowance	(27.00%)	(20.50%)	(28.40%)
Effective income tax rate	0.50%	(1.40%)	(2.20%)