Income Taxes - Reconciliation of Beginning and Ending Amount of Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized Tax Benefits, Beginning Balance	$ 12,980	$ 10,897	$ 7,994
Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions	0	593	0
Unrecognized Tax Benefits, Decrease Resulting from Prior Period Tax Positions	(1,127)	0	(385)
Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions	3,650	3,250	5,273
Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities	(523)	0	(643)
Unrecognized Tax Benefits, Reduction Resulting from Lapse of Applicable Statute of Limitations	(1,131)	(1,760)	(1,342)
Unrecognized Tax Benefits, Ending Balance	$ 13,849	$ 12,980	$ 10,897