Note 10 - Fair Value Measurements - Fair Value by Balance Sheet Grouping (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Sep. 30, 2022
Debt Securities, Available-for-Sale	$ 48,199	$ 49,844
Investment securities held-to-maturity, carrying amount	56,242	58,767
Investment securities held-to-maturity	49,666	50,266
Equity investment securities	1,390	1,374
Derivatives (included in Other Assets)	5,416	7,728
Derivatives (included in Other Liabilities)	2,394	3,712
Reported Value Measurement [Member]
Cash and cash equivalents	31,455	53,267
Debt Securities, Available-for-Sale	48,199	49,844
Investment securities held-to-maturity, carrying amount	56,242	58,767
Equity investment securities	1,390	1,374
Loans held for sale	13,232	13,780
Loans receivable, net	786,000	801,854
Accrued interest receivable	4,829	4,252
Restricted stock	6,815	7,104
Savings accounts	52,905	55,288
Checking and NOW accounts	276,890	298,833
Money market accounts	253,672	279,699
Certificates of deposit	156,715	151,503
Borrowings (excluding sub debt)	75,000	80,000
Subordinated debt	25,000	25,000
Accrued interest payable	1,246	543
Reported Value Measurement [Member] | Other Assets [Member]
Mortgage servicing rights (included in Other Assets)	80	87
Derivatives (included in Other Assets)	5,416	7,728
Reported Value Measurement [Member] | Other Liabilities [Member]
Derivatives (included in Other Liabilities)	2,394	3,712
Estimate of Fair Value Measurement [Member]
Cash and cash equivalents	31,455	53,267
Debt Securities, Available-for-Sale	48,199	49,844
Investment securities held-to-maturity	49,666	50,266
Equity investment securities	1,390	1,374
Loans held for sale	13,232	13,780
Loans receivable, net	745,771	763,311
Accrued interest receivable	4,829	4,252
Restricted stock	6,815	7,104
Savings accounts	52,905	55,288
Checking and NOW accounts	276,890	298,833
Money market accounts	253,672	279,699
Certificates of deposit	158,594	153,087
Borrowings (excluding sub debt)	75,135	80,022
Subordinated debt	27,075	25,045
Accrued interest payable	1,246	543
Estimate of Fair Value Measurement [Member] | Other Assets [Member]
Mortgage servicing rights (included in Other Assets)	106	117
Derivatives (included in Other Assets)	5,416	7,728
Estimate of Fair Value Measurement [Member] | Other Liabilities [Member]
Derivatives (included in Other Liabilities)	2,394	3,712
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member]
Cash and cash equivalents	31,455	53,267
Debt Securities, Available-for-Sale	0	0
Investment securities held-to-maturity	0	0
Equity investment securities	890	874
Loans held for sale	0	0
Loans receivable, net	0	0
Accrued interest receivable	0	0
Restricted stock	0	0
Savings accounts	0	0
Checking and NOW accounts	0	0
Money market accounts	0	0
Certificates of deposit	0	0
Borrowings (excluding sub debt)	0	0
Subordinated debt	0	0
Accrued interest payable	0	0
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member] | Other Assets [Member]
Mortgage servicing rights (included in Other Assets)	0	0
Derivatives (included in Other Assets)	0	0
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member] | Other Liabilities [Member]
Derivatives (included in Other Liabilities)	0	0
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Cash and cash equivalents	0	0
Debt Securities, Available-for-Sale	48,199	49,844
Investment securities held-to-maturity	49,666	50,266
Equity investment securities	0	0
Loans held for sale	0	0
Loans receivable, net	0	0
Accrued interest receivable	4,829	4,252
Restricted stock	6,815	7,104
Savings accounts	52,905	55,288
Checking and NOW accounts	276,890	298,833
Money market accounts	253,672	279,699
Certificates of deposit	158,594	153,087
Borrowings (excluding sub debt)	75,135	80,022
Subordinated debt	27,075	25,045
Accrued interest payable	1,246	543
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Other Assets [Member]
Mortgage servicing rights (included in Other Assets)	106	117
Derivatives (included in Other Assets)	5,416	7,728
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Other Liabilities [Member]
Derivatives (included in Other Liabilities)	2,394	3,712
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Cash and cash equivalents	0	0
Debt Securities, Available-for-Sale	0	0
Investment securities held-to-maturity	0	0
Equity investment securities	500	500
Loans held for sale	13,232	13,780
Loans receivable, net	745,771	763,311
Accrued interest receivable	0	0
Restricted stock	0	0
Savings accounts	0	0
Checking and NOW accounts	0	0
Money market accounts	0	0
Certificates of deposit	0	0
Borrowings (excluding sub debt)	0	0
Subordinated debt	0	0
Accrued interest payable	0	0
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member] | Other Assets [Member]
Mortgage servicing rights (included in Other Assets)	0	0
Derivatives (included in Other Assets)	0	0
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member] | Other Liabilities [Member]
Derivatives (included in Other Liabilities)	$ 0	$ 0