Note 4 - Fair Value of Financial Instruments - Financial Assets Measured on a Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Money Market Funds [Member]
Money market funds, Fair Value	$ 31,403	$ 30,834
Fair Value, Recurring [Member]
Investments, Fair Value Disclosure		8,162
Total assets	36,361	80,538
Fair Value, Recurring [Member] \| US Treasury Securities [Member]
Investments, Fair Value Disclosure	4,958	41,542
Fair Value, Recurring [Member] \| Money Market Funds [Member]
Money market funds, Fair Value	31,403	30,834
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member]
Investments, Fair Value Disclosure		0
Total assets	31,403	30,834
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| US Treasury Securities [Member]
Investments, Fair Value Disclosure	0	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| Money Market Funds [Member]
Money market funds, Fair Value	31,403	30,834
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member]
Investments, Fair Value Disclosure		8,162
Total assets	4,958	49,704
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| US Treasury Securities [Member]
Investments, Fair Value Disclosure	4,958	41,542
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Money Market Funds [Member]
Money market funds, Fair Value	0	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member]
Investments, Fair Value Disclosure		0
Total assets	0	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| US Treasury Securities [Member]
Investments, Fair Value Disclosure	0	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Money Market Funds [Member]
Money market funds, Fair Value	$ 0	$ 0

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://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482106/820-10-50-2

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- Definition

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.

+ References

No definition available.

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- Definition

Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482106/820-10-50-2

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