Loan Servicing Rights - Summary of Fair Values (Details) - Freddie Mac - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Servicing Assets at Fair Value [Line Items]
Mortgage servicing rights (MSR), fair value	$ 4,655	$ 5,469	$ 5,547
Mortgage servicing rights (MSR), average discount rates for estimating fair value	10.00%	9.50%	9.50%
Mortgage servicing rights (MSR), average conditional prepayment rates for estimating fair value	0.0703	0.0623	0.0631