Investment Securities - Securities Portfolio Presented by Contractual Maturity (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Sep. 30, 2021
Securities Available for Sale, Amortized Cost [Abstract]
Due after five years through ten years	$ 12,700
Amortized cost	13,075	$ 7,422
Securities Available for Sale, Fair Value [Abstract]
Five to ten years	12,043
Fair value	12,285	7,747
Securities Held to Maturity, Amortized Cost [Abstract]
One to five years	0
Five to ten years	0
Amortized cost	4,414	8,611
Securities Held to Maturity, Fair Value [Abstract]
Fair value	4,095	8,865
Debt Securities, Available-for-Sale and Held-to-Maturity, after Allowance for Credit Loss [Abstract]
Amortized cost	17,489	16,033
Fair value	16,380	16,612
Investment securities pledged to secure public deposits	16,699	16,358
Holdings of securities of any one issuer, other than securities issued by U.S. Government sponsored agencies, in amount greater than 10% of shareholders' equity	0	0
Asset Pledged as Collateral without Right \| Deposits
Debt Securities, Available-for-Sale and Held-to-Maturity, after Allowance for Credit Loss [Abstract]
Investment securities pledged to secure public deposits	1,800	5,100
U.S. GSE residential mortgage-backed securities
Securities Available for Sale, Amortized Cost [Abstract]
Without single maturity date	375
Amortized cost	375	722
Securities Available for Sale, Fair Value [Abstract]
Without single maturity date	242
Fair value	242	833
Securities Held to Maturity, Amortized Cost [Abstract]
Without single maturity date	1,778
Amortized cost	1,778	2,417
Securities Held to Maturity, Fair Value [Abstract]
Without single maturity date	1,618
Fair value	1,618	2,491
U.S. GSE commercial mortgage-backed securities
Securities Held to Maturity, Amortized Cost [Abstract]
Without single maturity date	2,636
Amortized cost	2,636	2,694
Securities Held to Maturity, Fair Value [Abstract]
Without single maturity date	2,477
Fair value	$ 2,477	$ 2,869

Amount of investment in debt security available for sale and held to maturity measured at amortized cost.

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Holdings of securities of any one issuer, other than the U.S. Government and its agencies, in an amount greater than 10% of shareholders' equity.

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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), without single maturity date and not allocated over maturity grouping.

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Fair value of investment in debt security measured at amortized cost (held-to-maturity) and investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount, after allowance for credit loss, of investment in debt security measured at amortized cost (held-to-maturity).

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Amount, after allowance for credit loss, of investment in debt security measured at amortized cost (held-to-maturity) with single maturity date and allocated without single maturity date, maturing in second through fifth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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