Stock-Based Compensation - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions		1 Months Ended			12 Months Ended
	Feb. 15, 2023	Feb. 28, 2023	Feb. 28, 2022	Feb. 28, 2014	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
2014 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Authorized plan extension period	5 years
Number of additional shares authorized (in shares)	600,000
Number of shares authorized (in shares)	1,350,000
2014 Director Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Authorized plan extension period			10 years
Number of additional shares authorized (in shares)			200,000
Number of shares authorized (in shares)			350,000
Common stock, capital shares reserved for future issuance (in shares)					190,600
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense					$ 0.6	$ 0.4	$ 0.5
Weighted average remaining contractual life					6 months
Restricted Stock | 2014 Director Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unvested restricted stock outstanding (in shares)					8,400	7,200
Maximum number of shares granted to any individual (in shares)				12,000
Number of shares issued to any individual (in shares)				4,000
Restricted stock issuable to eligible Board of Directors members annually (in shares)				2,400
Shares issued under the plan (in shares)		16,800	16,800
Shares issued, price per share (in dollars per share)		$ 43.22	$ 23.09
Restricted Stock | 2014 Director Plan | Vesting of First Anniversary
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage				50.00%
Restricted Stock | 2014 Director Plan | Vesting of Second Anniversary
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage				50.00%
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unvested restricted stock outstanding (in shares)					292,497	239,862
Compensation expense					$ 4.0	$ 3.7	$ 2.0
Amounts not yet recognized related to non-vested stock totaled					$ 1.4	$ 1.2
Weighted average remaining contractual life					1 year 6 months
Restricted Stock Units (RSUs) | 2014 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period				3 years
Restricted Stock Units (RSUs) | 2014 Equity Incentive Plan | Time Based Restricted Stock Unit
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period				3 years
Restricted Stock Units (RSUs) | 2014 Equity Incentive Plan | Performance Based Restricted Stock Unit
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period				3 years
Minimum | Restricted Stock Units (RSUs) | 2014 Equity Incentive Plan | Time Based Restricted Stock Unit
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Actual amount of RSUs earned based on cumulative earnings				50.00%
Maximum | Restricted Stock Units (RSUs) | 2014 Equity Incentive Plan | Performance Based Restricted Stock Unit
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Target RSUs granted range				50.00%