Note 6 - Fair Value Measurements - Fair Value by Major Security Type (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Sep. 30, 2023
Cash Equivalents	$ 1,060
Short-term marketable securities	8,777	$ 1,481
Fair Value, Nonrecurring [Member]
Cost Basis	9,837	3,798
Gross Unrealized Gain	5	0
Gross Unrealized Loss	(5)	(10)
Fair Value	9,837	3,788
Cash Equivalents	1,060	2,307
Short-term marketable securities	8,777	1,481
Long-term Securities	0	0
Fair Value, Inputs, Level 1 [Member] \| Fair Value, Nonrecurring [Member]
Cost Basis	1,060	2,307
Gross Unrealized Gain	0	0
Gross Unrealized Loss	0	0
Fair Value	1,060	2,307
Cash Equivalents		2,307
Short-term marketable securities		0
Long-term Securities		0
Fair Value, Inputs, Level 2 [Member] \| Fair Value, Nonrecurring [Member]
Cost Basis	8,777	1,491
Gross Unrealized Gain	5	0
Gross Unrealized Loss	(5)	(10)
Fair Value	8,777	1,481
Cash Equivalents	0	0
Short-term marketable securities	8,777	1,481
Long-term Securities	0	0
Fair Value, Inputs, Level 2 [Member] \| Fair Value, Nonrecurring [Member] \| Certificates of Deposit [Member]
Cost Basis	302	301
Gross Unrealized Gain	0	0
Gross Unrealized Loss	0	0
Fair Value	302	301
Cash Equivalents	0	0
Short-term marketable securities	302	301
Long-term Securities	0	0
Fair Value, Inputs, Level 2 [Member] \| Fair Value, Nonrecurring [Member] \| US States and Political Subdivisions Debt Securities [Member]
Cost Basis	3,707	926
Gross Unrealized Gain	4	0
Gross Unrealized Loss	(3)	(7)
Fair Value	3,708	919
Cash Equivalents	0	0
Short-term marketable securities	3,708	919
Long-term Securities	0	0
Fair Value, Inputs, Level 2 [Member] \| Fair Value, Nonrecurring [Member] \| Corporate Debt Securities [Member]
Cost Basis	3,607	264
Gross Unrealized Gain	1	0
Gross Unrealized Loss	(2)	(3)
Fair Value	3,606	261
Cash Equivalents	0	0
Short-term marketable securities	3,606	261
Long-term Securities	0	$ 0
Fair Value, Inputs, Level 2 [Member] \| Fair Value, Nonrecurring [Member] \| US Treasury and Government [Member]
Cost Basis	1,161
Gross Unrealized Gain	0
Gross Unrealized Loss	0
Fair Value	1,161
Cash Equivalents	0
Short-term marketable securities	1,161
Long-term Securities	$ 0

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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Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on 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
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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).

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
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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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