Fair Value Measurements - Assets Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Sep. 30, 2021
Financial Assets
Available for sale, at fair value	$ 12,285	$ 7,747
Loan servicing rights	4,353	3,690
U.S. GSE residential mortgage-backed securities
Financial Assets
Available for sale, at fair value	242	833
Corporate Bonds
Financial Assets
Available for sale, at fair value	12,043	6,914
Recurring
Financial Assets
Total	16,638	11,437
Recurring | U.S. GSE residential mortgage-backed securities
Financial Assets
Available for sale, at fair value	242	833
Recurring | Corporate Bonds
Financial Assets
Available for sale, at fair value	12,043	6,914
Recurring | Loan servicing rights
Financial Assets
Loan servicing rights	4,353	3,690
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Financial Assets
Total	0	0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. GSE residential mortgage-backed securities
Financial Assets
Available for sale, at fair value	0	0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Corporate Bonds
Financial Assets
Available for sale, at fair value	0	0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Loan servicing rights
Financial Assets
Loan servicing rights	0	0
Recurring | Significant Other Observable Inputs (Level 2)
Financial Assets
Total	12,285	7,747
Recurring | Significant Other Observable Inputs (Level 2) | U.S. GSE residential mortgage-backed securities
Financial Assets
Available for sale, at fair value	242	833
Recurring | Significant Other Observable Inputs (Level 2) | Corporate Bonds
Financial Assets
Available for sale, at fair value	12,043	6,914
Recurring | Significant Other Observable Inputs (Level 2) | Loan servicing rights
Financial Assets
Loan servicing rights	0	0
Recurring | Significant Unobservable Inputs (Level 3)
Financial Assets
Total	4,353	3,690
Recurring | Significant Unobservable Inputs (Level 3) | U.S. GSE residential mortgage-backed securities
Financial Assets
Available for sale, at fair value	0	0
Recurring | Significant Unobservable Inputs (Level 3) | Corporate Bonds
Financial Assets
Available for sale, at fair value	0	0
Recurring | Significant Unobservable Inputs (Level 3) | Loan servicing rights
Financial Assets
Loan servicing rights	$ 4,353	$ 3,690