Stock Award Plans - Narrative (Details) - USD ($)	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Contractual term of award (in years)	10 years
Options granted (in shares)	779,740	352,043	0
Compensation cost for stock options	$ 1,875,000	$ 1,296,000	$ 1,676,000
Stock Option Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost for stock options, net of forfeitures	$ 4,590,961
Restricted Stock Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity instruments other than options, nonvested (in shares)	495,782	489,777	522,991	409,469
Fair market value at date of grant at restricted stock	$ 12,097,081
Compensation cost for stock options	$ 4,512,000	$ 4,367,000	$ 4,473,000
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period (in years)	3 years
Minimum | Restricted Stock Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period (in years)	1 year
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period (in years)	5 years
Maximum | Restricted Stock Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period (in years)	7 years
2020 Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for grant (in shares)	3,200,000
Shares available for issuance (in shares)	1,129,615