Employee Benefit Plans Employee Benefit Plans - Employee Stock Purchase Plan, Incentive Bonus Plan and Stock-Based Compensation (Details) - USD ($)	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Discounted Price For Purchasing Company's Common Stock	85.00%
Employee Stock Purchase Plan, Maximum Percent of Annual Compensation	15.00%
Fair Market Value Of Common Stock Available For Purchase To Eligible Employees Maximum	$ 25,000
Stock Issued During Period, Shares, Employee Stock Purchase Plans	137,347	143,960	164,193
Stock Issued During Period, Value, Employee Stock Purchase Plan	$ 15,300,000	$ 11,000,000.0	$ 10,700,000
Salary and Wage, Officer, Excluding Cost of Good and Service Sold	$ 29,900,000	$ 35,400,000	$ 40,500,000
Shares available for grant	19,700,000
Employee Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance, shares	2,300,000
Share-based Payment Arrangement [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance, shares	21,300,000
Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Additional Shares Authorized	18,900,000