Regulatory Capital - Bank's Actual Capital Amounts And Ratios (Details) $ in Thousands	Mar. 31, 2021 USD ($)	Sep. 30, 2020 USD ($)
Consolidated
Total capital (to risk weighted assets) Actual Amount	$ 188,352	$ 168,617
Tier 1 capital (to risk-weighted assets) Actual Amount	151,517	133,520
Common equity tier 1 capital (to risk-weighted assets) Actual Amount	151,517	133,520
Tier 1 capital (to average adjusted total assets) Actual Amount	$ 151,517	$ 133,520
Total capital (to risk weighted assets) Actual Ratio	13.82	13.37
Tier 1 capital (to risk-weighted assets) Actual Ratio	11.12	10.58
Common equity tier 1 capital (to risk-weighted assets) Actual Ratio	11.12%	10.58%
Tier 1 capital (to average adjusted total assets) Actual Ratio	9.36	8.53
Total capital (to risk weighted assets) Minimum For Capital Adequacy Purposes Amount	$ 108,998	$ 100,929
Tier 1 capital (to risk-weighted assets) Minimum For Capital Adequacy Purposes Amount	81,748	75,697
Common equity tier 1 capital (to risk-weighted assets) Minimum For Capital Adequacy Purposes Amount	61,311	56,773
Tier 1 capital (to average adjusted total assets) Minimum For Capital Adequacy Purposes Amount	$ 64,719	$ 62,617
Total capital (to risk weighted assets) Minimum For Capital Adequacy Purposes Ratio	8.00	8.00
Tier 1 capital (to risk-weighted assets) Minimum For Capital Adequacy Purposes Ratio	6.00	6.00
Common equity tier 1 capital (to risk-weighted assets) Minimum For Capital Adequacy Purposes Ratio	4.50%	4.50%
Tier 1 capital (to average adjusted total assets) Minimum For Capital Adequacy Purposes Ratio	4.00	4.00
Bank [Member]
Total capital (to risk weighted assets) Actual Amount	$ 180,839	$ 160,452
Tier 1 capital (to risk-weighted assets) Actual Amount	163,835	145,152
Common equity tier 1 capital (to risk-weighted assets) Actual Amount	163,835	145,152
Tier 1 capital (to average adjusted total assets) Actual Amount	$ 163,835	$ 145,152
Total capital (to risk weighted assets) Actual Ratio	13.30	12.75
Tier 1 capital (to risk-weighted assets) Actual Ratio	12.05	11.53
Common equity tier 1 capital (to risk-weighted assets) Actual Ratio	12.05%	11.53%
Tier 1 capital (to average adjusted total assets) Actual Ratio	10.22	9.37
Total capital (to risk weighted assets) Minimum For Capital Adequacy Purposes Amount	$ 108,794	$ 100,672
Tier 1 capital (to risk-weighted assets) Minimum For Capital Adequacy Purposes Amount	81,596	75,504
Common equity tier 1 capital (to risk-weighted assets) Minimum For Capital Adequacy Purposes Amount	61,197	56,428
Tier 1 capital (to average adjusted total assets) Minimum For Capital Adequacy Purposes Amount	$ 64,103	$ 61,966
Total capital (to risk weighted assets) Minimum For Capital Adequacy Purposes Ratio	8.00	8.00
Tier 1 capital (to risk-weighted assets) Minimum For Capital Adequacy Purposes Ratio	6.00	6.00
Common equity tier 1 capital (to risk-weighted assets) Minimum For Capital Adequacy Purposes Ratio	4.50%	4.50%
Tier 1 capital (to average adjusted total assets) Minimum For Capital Adequacy Purposes Ratio	4.00	4.00
Total capital (to risk weighted assets) Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions Amount	$ 135,993	$ 125,840
Tier 1 capital (to risk-weighted assets) Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions Amount	108,794	100,672
Common equity tier 1 capital (to risk-weighted assets) Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions Amount	88,395	81,796
Tier 1 capital (to average adjusted total assets) Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions Amount	$ 80,129	$ 77,458
Total capital (to risk weighted assets) Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions Ratio	10.00	10.00
Tier 1 capital (to risk-weighted assets) Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions Ratio	8.00	8.00
Common equity tier 1 capital (to risk-weighted assets) Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions Ratio	6.50%	6.50%
Tier 1 capital (to average adjusted total assets) Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions Ratio	5.00	5.00

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