Note 2 - Stock Based Compensation - Option Transaction Summary (Details) - $ / shares |
12 Months Ended | ||
|---|---|---|---|
Sep. 30, 2022 |
Sep. 30, 2021 |
Sep. 30, 2020 |
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| Options, outstanding (in shares) | 301,514 | 337,100 | 290,750 |
| Weighted-average exercise price, outstanding (in dollars per share) | $ 16.25 | $ 12.48 | $ 11.86 |
| Granted (in shares) | 62,730 | 105,089 | 121,350 |
| Weighted-average exercise price, Granted (in dollars per share) | $ 66.48 | $ 23.74 | $ 12.43 |
| Weighted-average fair value, Granted (in dollars per share) | $ 25.54 | $ 8.14 | $ 4.62 |
| Exercised (in shares) | (125,651) | (101,966) | (26,750) |
| Weighted-average exercise price, Exercised (in dollars per share) | $ 12.92 | $ 12.47 | $ 4.01 |
| Forfeited and expired (in shares) | (2,084) | (38,709) | (48,250) |
| Weighted-average exercise price, Forfeited or Expired (in dollars per share) | $ 19.94 | $ 13.68 | $ 13.35 |
| Options, outstanding (in shares) | 236,509 | 301,514 | 337,100 |
| Weighted-average exercise price, outstanding (in dollars per share) | $ 31.30 | $ 16.25 | $ 12.48 |
| X | ||||||||||
- Definition For presentations that combine terminations, 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 or that expired. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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- Definition Weighted average price of options that were either forfeited or expired. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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- Definition Gross number of share options (or share units) granted during the period. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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| X | ||||||||||
- Definition The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Number of options outstanding, including both vested and non-vested options. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Weighted average price at which option holders acquired shares when converting their stock options into shares. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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| X | ||||||||||
- Definition Number of share options (or share units) exercised during the current period. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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