Loan Servicing Rights - Summary of Fair Values (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Freddie Mac
Servicing Assets at Fair Value [Line Items]
Mortgage servicing rights (MSR), fair value	$ 5,469	$ 5,547	$ 3,656
Mortgage servicing rights (MSR), average discount rates for estimating fair value	9.50%	9.50%	9.00%
Mortgage servicing rights (MSR), average conditional prepayment rates for estimating fair value	0.0623	0.0631	0.1271
SBA
Servicing Assets at Fair Value [Line Items]
Mortgage servicing rights (MSR), fair value		$ 99
Mortgage servicing rights (MSR), average discount rates for estimating fair value		15.00%	15.00%
Mortgage servicing rights (MSR), average conditional prepayment rates for estimating fair value		0.1785