Retirement and Deferred Compensation Plan - Deferred Compensation Plan (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Accrued compensations and benefits	$ 50,242	$ 57,781
Deferred Compensation Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Deferred compensation plan assets	6,500	3,200
Accrued compensations and benefits	6,500	5,500
Employer contribution to deferred compensation plan	$ 200	$ 200	$ 200