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Note 2 - Securities - Available-for-sale Securities (Details) - USD ($)	Sep. 30, 2023	Dec. 31, 2022
Securities available for sale, amortized cost	$ 685,455,000	$ 685,646,000
Securities available for sale, gross unrealized gains	49,000	571,000
Securities available for sale, gross unrealized losses	(93,199,000)	(83,281,000)
Securities available for sale, fair value	592,305,000	602,936,000
US Government Agencies Debt Securities [Member]
Securities available for sale, amortized cost	452,330,000	453,836,000
Securities available for sale, gross unrealized gains	0	0
Securities available for sale, gross unrealized losses	(68,251,000)	(65,092,000)
Securities available for sale, fair value	384,079,000	388,744,000
Collateralized Mortgage-Backed Securities [Member]
Securities available for sale, amortized cost	35,699,000	38,002,000
Securities available for sale, gross unrealized gains	2,000	19,000
Securities available for sale, gross unrealized losses	(7,685,000)	(6,068,000)
Securities available for sale, fair value	28,016,000	31,953,000
Municipal General Obligation Bonds [Member]
Securities available for sale, amortized cost	166,922,000	163,041,000
Securities available for sale, gross unrealized gains	33,000	450,000
Securities available for sale, gross unrealized losses	(13,530,000)	(9,058,000)
Securities available for sale, fair value	153,425,000	154,433,000
Municipal Revenue Bonds [Member]
Securities available for sale, amortized cost	30,004,000	30,267,000
Securities available for sale, gross unrealized gains	14,000	102,000
Securities available for sale, gross unrealized losses	(3,733,000)	(3,063,000)
Securities available for sale, fair value	26,285,000	27,306,000
Other Debt and Equity Securities [Member]
Securities available for sale, amortized cost	500,000	500,000
Securities available for sale, gross unrealized gains	0	0
Securities available for sale, gross unrealized losses	0	0
Securities available for sale, fair value	$ 500,000	$ 500,000

X

- Definition

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

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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X

- Definition

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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X

- Definition

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
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(1))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479440/944-210-S99-1

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

Reference 3: 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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X

- Definition

Amount 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 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (aa)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481830/320-10-45-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(6))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479853/942-210-S99-1

Reference 4: 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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