Note 5 - Debt Securities - Held to Maturity (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Debt securities held to maturity (at amortized cost; estimated fair value - $86,627 - 2022, $101,242 - 2021)	$ 96,163	$ 98,060
Unrealized Gains	0	3,187
Unrealized Losses	9,536	5
Debt Securities, Held-to-maturity, Fair Value	86,627	101,242
Tax Exempt State and Political Subdivisions General Obligations [Member]
Debt securities held to maturity (at amortized cost; estimated fair value - $86,627 - 2022, $101,242 - 2021)	70,401	71,807
Unrealized Gains	0	2,583
Unrealized Losses	6,480	0
Debt Securities, Held-to-maturity, Fair Value	63,921	74,390
Tax Exempt State and Political Subdivisions Water And Sewer Revenues [Member]
Debt securities held to maturity (at amortized cost; estimated fair value - $86,627 - 2022, $101,242 - 2021)	8,006	8,192
Unrealized Gains	0	210
Unrealized Losses	672	0
Debt Securities, Held-to-maturity, Fair Value	7,334	8,402
Tax Exempt State and Political Subdivisions Lease Revenues [Member]
Debt securities held to maturity (at amortized cost; estimated fair value - $86,627 - 2022, $101,242 - 2021)	4,234	4,316
Unrealized Gains	0	74
Unrealized Losses	534	0
Debt Securities, Held-to-maturity, Fair Value	3,700	4,390
Tax Exempt State and Political Subdivisions Sales Tax Revenues [Member]
Debt securities held to maturity (at amortized cost; estimated fair value - $86,627 - 2022, $101,242 - 2021)	4,515	4,582
Unrealized Gains	0	106
Unrealized Losses	689	0
Debt Securities, Held-to-maturity, Fair Value	3,826	4,688
Tax Exempt State and Political Subdivisions Various Tax Revenues [Member]
Debt securities held to maturity (at amortized cost; estimated fair value - $86,627 - 2022, $101,242 - 2021)	5,511
Unrealized Gains	0
Unrealized Losses	871
Debt Securities, Held-to-maturity, Fair Value	4,640
Tax Exempt State and Political Subdivisions Other Revenues [Member]
Debt securities held to maturity (at amortized cost; estimated fair value - $86,627 - 2022, $101,242 - 2021)	3,496	9,163
Unrealized Gains	0	214
Unrealized Losses	290	5
Debt Securities, Held-to-maturity, Fair Value	$ 3,206	$ 9,372

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

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Fair value of investment in debt security measured at amortized cost (held-to-maturity).

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