Stock Compensation Plans: Disclosure of Share-based Compensation Arrangements by Share-based Payment Award (Details) - $ / shares	6 Months Ended
Mar. 31, 2025	Mar. 31, 2024
Shares:
Options outstanding, beginning of period (shares)	306,240	369,150
Exercised (shares)	(34,360)	(29,900)
Forfeited (shares)	(5,900)	(10,140)
Options outstanding, end of period (shares)	265,980	329,110
Weighted Average Exercise Price (in dollars per share):
Options outstanding, beginning of period (dollars per share)	$ 25.21	$ 24.00
Exercised (dollars per share)	27.40	13.03
Forfeited (dollars per share)	27.96	25.71
Options outstanding, end of period (dollars per share)	$ 25.82	$ 24.95

The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan.

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- Definition

Number of options outstanding, including both vested and non-vested options.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(i)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

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- Definition

Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

+ References

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- Definition

Weighted average price at which option holders acquired shares when converting their stock options into shares.

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- Definition

Weighted average price at which grantees could have acquired the underlying shares with respect to stock options that were terminated.

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- Definition

Number of share options (or share units) exercised during the current period.

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