Note 4 - Fair Value Measurements - Fair Value by Major Security Type (Details) - USD ($)	Sep. 30, 2017	Sep. 30, 2016
Short-term marketable securities	$ 4,359,542	$ 2,936,124
Long-term marketable securities	711,124	2,187,536
Fair Value, Measurements, Nonrecurring [Member]
Cost Basis	5,127,192	5,125,209
Unrealized Gains (Losses)	(1,269)	(1,549)
Fair Value	5,125,923	5,219,198
Cash Equivalents	55,257	95,538
Short-term marketable securities	4,359,542	2,936,124
Long-term marketable securities	711,124	2,187,536
Fair Value, Measurements, Nonrecurring [Member] \| Fair Value, Inputs, Level 1 [Member]
Cost Basis	55,257
Unrealized Gains (Losses)
Fair Value	55,257	95,538
Cash Equivalents	55,257	95,538
Short-term marketable securities
Long-term marketable securities
Fair Value, Measurements, Nonrecurring [Member] \| Fair Value, Inputs, Level 2 [Member]
Cost Basis	5,071,935	5,125,209
Unrealized Gains (Losses)	(1,269)	(1,549)
Fair Value	5,070,666	5,123,660
Cash Equivalents
Short-term marketable securities	4,359,542	2,936,124
Long-term marketable securities	711,124	2,187,536
Fair Value, Measurements, Nonrecurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Certificates of Deposit [Member]
Cost Basis	2,436,647	3,236,168
Unrealized Gains (Losses)
Fair Value	2,436,647	3,236,168
Short-term marketable securities	1,937,647	1,299,133
Long-term marketable securities	499,000	1,937,035
Fair Value, Measurements, Nonrecurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| US States and Political Subdivisions Debt Securities [Member]
Cost Basis	25,315	140,637
Unrealized Gains (Losses)	(12)
Fair Value	25,303	140,637
Cash Equivalents
Short-term marketable securities	25,303	140,637
Fair Value, Measurements, Nonrecurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Corporate Debt Securities [Member]
Cost Basis	2,609,973	1,748,404
Unrealized Gains (Losses)	(1,257)	(1,549)
Fair Value	2,608,716	1,746,855
Short-term marketable securities	2,396,592	1,496,354
Long-term marketable securities	$ 212,124	$ 250,501

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258

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This item represents the cost of debt securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (aa)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27161-111563

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.2)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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Amount before tax of unrealized gain (loss) in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

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Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Amount of investments in debt and equity securities, including, but not limited to, held-to-maturity, trading and available-for-sale expected to be converted to cash, sold or exchanged within one year or the normal operating cycle, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section 45
-Paragraph 1
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=82887183&loc=d3e6676-107765

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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Total debt and equity financial instruments including: (1) securities held-to-maturity and (2) securities available-for-sale that will be held for the long-term.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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