Note 3 - Cash, Cash Equivalents and Investments - CD Maturity Dates (Details) - USD ($) |
Dec. 31, 2017 |
Sep. 30, 2017 |
|---|---|---|
| Less than one year | $ 5,385,150 | $ 5,937,150 |
| 1-5 years | 20,357,000 | 19,816,000 |
| Total | $ 25,742,150 | $ 25,753,150 |
| X | ||||||||||
- Definition Amount after other than temporary impairment (OTTI) accretion, of investments in debt securities classified as held-to-maturity. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
- Definition Carrying amount of debt securities accounted for as held-to-maturity, net of adjustments including, but not limited to, accretion, amortization, collection of cash, previous other-than-temporary impairments (OTTI) recognized, and fair value hedge accounting adjustments, maturing in the next fiscal year through the fifth fiscal year following the latest fiscal year. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
- Definition Carrying amount of debt securities accounted for as held-to-maturity, net of adjustments including, but not limited to, accretion, amortization, collection of cash, previous other-than-temporary impairments (OTTI) recognized, and fair value hedge accounting adjustments, maturing in the next fiscal year following the latest fiscal year. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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