Note 5 - Fair Value Measurements - Fair Value by Major Security Type (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Sep. 30, 2019
Short-term marketable securities	$ 4,265	$ 3,695
Long-term Securities	3,805	1,385
Fair Value, Nonrecurring [Member]
Cost Basis	8,428	5,345
Unrealized Gains (Losses)	7	11
Fair Value	8,435	5,356
Cash Equivalents	365	276
Short-term marketable securities	4,265	3,695
Long-term Securities	3,805	1,385
Fair Value, Nonrecurring [Member] \| Fair Value, Inputs, Level 1 [Member]
Cost Basis	365	276
Unrealized Gains (Losses)
Fair Value	365	276
Cash Equivalents	365	276
Short-term marketable securities
Long-term Securities
Fair Value, Nonrecurring [Member] \| Fair Value, Inputs, Level 2 [Member]
Cost Basis	8,063	5,069
Unrealized Gains (Losses)	7	11
Fair Value	8,070	5,080
Cash Equivalents
Short-term marketable securities	4,265	3,695
Long-term Securities	3,805	1,385
Fair Value, Nonrecurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Certificates of Deposit [Member]
Cost Basis	1,195	972
Unrealized Gains (Losses)
Fair Value	1,195	972
Cash Equivalents
Short-term marketable securities		499
Long-term Securities	1,195	473
Fair Value, Nonrecurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| US States and Political Subdivisions Debt Securities [Member]
Cost Basis	3,777	240
Unrealized Gains (Losses)	4
Fair Value	3,781	240
Cash Equivalents
Short-term marketable securities	2,432	80
Long-term Securities	1,350	160
Fair Value, Nonrecurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Corporate Debt Securities [Member]
Cost Basis	3,091	3,857
Unrealized Gains (Losses)	3	11
Fair Value	3,094	3,868
Cash Equivalents
Short-term marketable securities	1,833	3,116
Long-term Securities	$ 1,260	$ 752

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

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-Publisher FASB
-Name Accounting Standards Codification
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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
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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 investment in marketable security, classified as current.

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Amount of investment in marketable security, classified as noncurrent.

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