Loans - Loans Categorized by Class and Internally Assigned Risk Grades (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Sep. 30, 2021
Loans Portfolio by Credit Risk Rating [Abstract]
Total	$ 1,623,531	$ 1,247,125
Pass
Loans Portfolio by Credit Risk Rating [Abstract]
Total	1,590,893	1,195,253
Special Mention
Loans Portfolio by Credit Risk Rating [Abstract]
Total	11,545	26,551
Substandard
Loans Portfolio by Credit Risk Rating [Abstract]
Total	21,093	25,318
Doubtful
Loans Portfolio by Credit Risk Rating [Abstract]
Total	0	3
Residential real estate
Loans Portfolio by Credit Risk Rating [Abstract]
Total	516,258	444,140
Residential real estate | Pass
Loans Portfolio by Credit Risk Rating [Abstract]
Total	512,595	433,433
Residential real estate | Special Mention
Loans Portfolio by Credit Risk Rating [Abstract]
Total	512	5,114
Residential real estate | Substandard
Loans Portfolio by Credit Risk Rating [Abstract]
Total	3,151	5,590
Residential real estate | Doubtful
Loans Portfolio by Credit Risk Rating [Abstract]
Total	0	3
Multi-family
Loans Portfolio by Credit Risk Rating [Abstract]
Total	575,061	266,714
Multi-family | Pass
Loans Portfolio by Credit Risk Rating [Abstract]
Total	571,128	263,400
Multi-family | Special Mention
Loans Portfolio by Credit Risk Rating [Abstract]
Total	0	2,856
Multi-family | Substandard
Loans Portfolio by Credit Risk Rating [Abstract]
Total	3,933	458
Multi-family | Doubtful
Loans Portfolio by Credit Risk Rating [Abstract]
Total	0	0
Commercial [Member]
Loans Portfolio by Credit Risk Rating [Abstract]
Total	472,984	348,807
Commercial [Member] | Pass
Loans Portfolio by Credit Risk Rating [Abstract]
Total	453,321	316,894
Commercial [Member] | Special Mention
Loans Portfolio by Credit Risk Rating [Abstract]
Total	8,085	16,274
Commercial [Member] | Substandard
Loans Portfolio by Credit Risk Rating [Abstract]
Total	11,578	15,639
Commercial [Member] | Doubtful
Loans Portfolio by Credit Risk Rating [Abstract]
Total	0	0
Commercial and Industrial
Loans Portfolio by Credit Risk Rating [Abstract]
Total	46,285	172,077
Commercial and Industrial | Pass
Loans Portfolio by Credit Risk Rating [Abstract]
Total	43,314	167,906
Commercial and Industrial | Special Mention
Loans Portfolio by Credit Risk Rating [Abstract]
Total	540	540
Commercial and Industrial | Substandard
Loans Portfolio by Credit Risk Rating [Abstract]
Total	2,431	3,631
Commercial and Industrial | Doubtful
Loans Portfolio by Credit Risk Rating [Abstract]
Total	0	0
Construction and land development
Loans Portfolio by Credit Risk Rating [Abstract]
Total	12,907	15,374
Construction and land development | Pass
Loans Portfolio by Credit Risk Rating [Abstract]
Total	10,499	13,607
Construction and land development | Special Mention
Loans Portfolio by Credit Risk Rating [Abstract]
Total	2,408	1,767
Construction and land development | Substandard
Loans Portfolio by Credit Risk Rating [Abstract]
Total	0	0
Construction and land development | Doubtful
Loans Portfolio by Credit Risk Rating [Abstract]
Total	0	0
Consumer
Loans Portfolio by Credit Risk Rating [Abstract]
Total	36	13
Consumer | Pass
Loans Portfolio by Credit Risk Rating [Abstract]
Total	36	13
Consumer | Special Mention
Loans Portfolio by Credit Risk Rating [Abstract]
Total	0	0
Consumer | Substandard
Loans Portfolio by Credit Risk Rating [Abstract]
Total	0	0
Consumer | Doubtful
Loans Portfolio by Credit Risk Rating [Abstract]
Total	$ 0	$ 0