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Note 3 - Debt Securities Available for Sale and Held to Maturity - Credit Quality (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Held to Maturity, Amortized Cost	$ 826,506	$ 844,635
AAA/AA/A [Member]
Held to Maturity, Amortized Cost	642,875
BBB+/BBB [Member]
Held to Maturity, Amortized Cost	183,182
NR [Member]
Held to Maturity, Amortized Cost	449
Agency Residential MBS [Member]
Held to Maturity, Amortized Cost	46,433	57,927
Agency Residential MBS [Member] | AAA/AA/A [Member]
Held to Maturity, Amortized Cost	45,984
Agency Residential MBS [Member] | BBB+/BBB [Member]
Held to Maturity, Amortized Cost	0
Agency Residential MBS [Member] | NR [Member]
Held to Maturity, Amortized Cost	449
US States and Political Subdivisions Debt Securities [Member]
Held to Maturity, Amortized Cost	39,528	51,261
US States and Political Subdivisions Debt Securities [Member] | AAA/AA/A [Member]
Held to Maturity, Amortized Cost	39,528
US States and Political Subdivisions Debt Securities [Member] | BBB+/BBB [Member]
Held to Maturity, Amortized Cost	0
US States and Political Subdivisions Debt Securities [Member] | NR [Member]
Held to Maturity, Amortized Cost	0
Corporate Debt Securities [Member]
Held to Maturity, Amortized Cost	740,545	$ 735,447
Corporate Debt Securities [Member] | AAA/AA/A [Member]
Held to Maturity, Amortized Cost	557,363
Corporate Debt Securities [Member] | BBB+/BBB [Member]
Held to Maturity, Amortized Cost	183,182
Corporate Debt Securities [Member] | NR [Member]
Held to Maturity, Amortized Cost	$ 0

X

- Definition

Amount excluding accrued interest, before allowance for credit loss, of investment in debt security measured at amortized cost (held-to-maturity).

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479344/326-20-45-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 3B
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-3B

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-5

+ Details

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Balance Type:	debit
Period Type:	instant

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- Details

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- Details

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- Details

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