Income Taxes - Reconciliation of Beginning and Ending Amount of Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Unrecognized Tax Benefits [Roll Forward]
Unrecognized Tax Benefits, Beginning Balance	$ 13,849	$ 12,980	$ 10,897
Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions	4,769	0	593
Unrecognized Tax Benefits, Decrease Resulting from Prior Period Tax Positions	(1,956)	(1,127)	0
Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions	4,277	3,650	3,250
Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities	0	(523)	0
Unrecognized Tax Benefits, Reduction Resulting from Lapse of Applicable Statute of Limitations	(1,060)	(1,131)	(1,760)
Unrecognized Tax Benefits, Ending Balance	$ 19,879	$ 13,849	$ 12,980