Note 4 - Stock-based Compensation - Stock Option Activity (Details) - $ / shares |
6 Months Ended | |
|---|---|---|
Mar. 31, 2017 |
Mar. 31, 2016 |
|
| Options, outstanding (in shares) | 54,800 | |
| Weighted-average exercise price, outstanding (in dollars per share) | $ 3.13 | |
| Exercised (in shares) | (15,750) | (57,050) |
| Exercised (in dollars per share) | $ 3.98 | |
| Options, outstanding (in shares) | 39,050 | |
| Weighted-average exercise price, outstanding (in dollars per share) | $ 2.78 | |
| X | ||||||||||
- Definition Number of options outstanding, including both vested and non-vested options. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
- 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/presentationRef
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| X | ||||||||||
- Definition Weighted average price at which option holders acquired shares when converting their stock options into shares. No definition available.
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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/presentationRef
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