Note 2 - Stock Based Compensation - Restricted Stock Transactions (Details) - Restricted Stock [Member] - $ / shares	12 Months Ended
Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Balance, unvested shares (in shares)	108,839	109,070	130,440
Balance, weighted-average grant date fair value (in dollars per share)	$ 17.14	$ 12.98	$ 13.25
Granted, unvested shares (in shares)	29,512	39,807	19,455
Granted, weighted-average grant date fair value (in dollars per share)	$ 65.90	$ 24.20	$ 10.30
Vested, unvested shares (in shares)	(37,094)	(35,840)	(29,950)
Vested, weighted-average grant date fair value (in dollars per share)	$ 17.78	$ 12.48	$ 13.36
Forfeited, unvested shares (in shares)	(2,749)	(4,198)	(10,875)
Forfeited, weighted-average grant date fair value (in dollars per share)	$ 16.84	$ 15.45	$ 12.14
Balance, unvested shares (in shares)	98,508	108,839	109,070
Balance, weighted-average grant date fair value (in dollars per share)	$ 31.51	$ 17.14	$ 12.98

The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

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Weighted average fair value as of the grant date of equity-based award plans other than stock (unit) option plans that were not exercised or put into effect as a result of the occurrence of a terminating event.

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The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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- Definition

The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(ii)
-URI https://asc.fasb.org/extlink&oid=128089324&loc=d3e5070-113901

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(i)
-URI https://asc.fasb.org/extlink&oid=128089324&loc=d3e5070-113901

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Per share or unit weighted-average fair value of nonvested award under share-based payment arrangement. Excludes share and unit options.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(i)
-URI https://asc.fasb.org/extlink&oid=128089324&loc=d3e5070-113901

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(ii)
-URI https://asc.fasb.org/extlink&oid=128089324&loc=d3e5070-113901

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The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

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The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

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