Income Taxes - Unrecognized Tax Benefits - Tabular Disclosure (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]
Beginning Balance	$ 1,679	$ 2,006	$ 16,722
Reductions from lapses in statutes of limitations	(1,381)	(327)	(14,716)
Ending Balance	$ 298	$ 1,679	$ 2,006