Equity Compensation Plans - Restricted Stock (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
Restricted Stock
Number of Shares
Unvested, beginning of period (in shares)	75,833
Granted (in shares)	278,930
Vested (in shares)	(45,835)
Forfeited (in shares)	(24,665)
Unvested, end of period (in shares)	284,263	75,833
Weighted-Average Grant Date Fair Value
Unvested, beginning of period (in dollars per share)	$ 19.87
Granted (in dollars per share)	19.73
Vested (in dollars per share)	19.62
Forfeited (in dollars per share)	19.71
Unvested, end of period (in dollars per share)	$ 19.78	$ 19.87
Compensation expenses	$ 1.5	$ 0.9
Unrealized compensation cost	$ 4.7
Weighted-average term for recognizing unrealized compensation cost	3 years 11 months 4 days
Total fair value of shares vested	$ 0.9	$ 0.9
Restricted Stock | Three-year Vesting Period
Restricted Stock
Award vesting period	3 years
Number of Shares
Granted (in shares)	44,642
Restricted Stock | Five-year vesting period
Restricted Stock
Award vesting period	5 years
Number of Shares
Granted (in shares)	234,288
Restricted Stock Units (RSUs)
Restricted Stock
Award vesting period	3 years
Number of Shares
Granted (in shares)	51,097	0
Forfeited (in shares)	(3,421)
Unvested, end of period (in shares)	47,676
Weighted-Average Grant Date Fair Value
Granted (in dollars per share)	$ 19.73
Forfeited (in dollars per share)	19.73
Unvested, end of period (in dollars per share)	$ 19.73
Compensation expenses	$ 0.2	$ 0.0
Unrealized compensation cost	$ 0.7
Weighted-average term for recognizing unrealized compensation cost	2 years 4 months 20 days