Income Taxes - Reconciliation 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]
Balance at beginning of year	$ 3,358	$ 3,358	$ 3,441
Additions for tax positions related to current year	0	0	0
Additions for tax positions related to prior years	0	0	0
Reductions in tax positions of prior years	0	0	0
Lapse of statute of limitations	0	0	(83)
Balance at end of year	$ 3,358	$ 3,358	$ 3,358