Note 3 - U.S. Treasury Securities, Available-for-sale - Available-for-sale- Investments (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Fair value	$ 148,820	$ 0
Treasury Bill 1/2/2024 Maturity [Member]
Amortized cost	49,671
Gross unrealized gains	9
Gross unrealized losses	0
Fair value	49,680
Treasury Bill 2/15/2024 Maturity [Member]
Amortized cost	49,992
Gross unrealized gains	8
Gross unrealized losses	0
Fair value	50,000
Treasury Bill 4/30/2024 Maturity [Member]
Amortized cost	49,140
Gross unrealized gains	0
Gross unrealized losses	0
Fair value	49,140
US Treasury Securities [Member]
Amortized cost	148,803
Gross unrealized gains	17
Gross unrealized losses	0
Fair value	$ 148,820

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).

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

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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
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
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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
-Topic 944
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
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-Publisher FASB
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
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