Note 3 - U.S. Treasury Securities, Available-for-sale - Available-for-sale- Investments (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
U.S. Treasury securities, available for sale, amortized cost	$ 125,367	$ 100,412
Pledged assets, available for sale	125,440	100,551
U.S. Treasury Note, 4.625%, 6/30/2026 Maturity [Member]
U.S. Treasury securities, available for sale, amortized cost	100,205	100,412
Gross unrealized gains	408	139
Gross unrealized losses	0	0
Pledged assets, available for sale	100,613	100,551
U.S. Treasury Bill maturing 12/4/2025 [Member]
U.S. Treasury securities, available for sale, amortized cost	24,816
Gross unrealized gains	11
Gross unrealized losses	0
Pledged assets, available for sale	24,827
US Treasury Securities [Member]
U.S. Treasury securities, available for sale, amortized cost	125,021	100,412
Gross unrealized gains	419	139
Gross unrealized losses	0	0
Pledged assets, available for sale	$ 125,440	$ 100,551

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
-Paragraph 2
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-2

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Amortized cost excluding accrued interest, before allowance for credit loss, 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 326
-SubTopic 30
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479130/326-30-45-1

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Amount excluding accrued interest, 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/2009/role/commonPracticeRef
-Topic 326
-SubTopic 30
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479130/326-30-45-1

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