Note 5 - Debt Securities - Held to Maturity (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Tax-exempt state and political subdivisions	$ 93,737	$ 94,227	[1]
Unrealized Gains	0	0
Unrealized Losses	6,708	5,908
Debt Securities, Held-to-maturity, Fair Value	87,029	88,319	[1]
Tax Exempt State and Political Subdivisions General Obligations [Member]
Tax-exempt state and political subdivisions	68,603	68,966
Unrealized Gains	0	0
Unrealized Losses	4,567	4,029
Debt Securities, Held-to-maturity, Fair Value	64,036	64,937
Tax Exempt State and Political Subdivisions Water And Sewer Revenues [Member]
Tax-exempt state and political subdivisions	7,768	7,816
Unrealized Gains	0	0
Unrealized Losses	461	417
Debt Securities, Held-to-maturity, Fair Value	7,307	7,399
Tax Exempt State and Political Subdivisions Lease Revenues [Member]
Tax-exempt state and political subdivisions	4,130	4,151
Unrealized Gains	0	0
Unrealized Losses	354	321
Debt Securities, Held-to-maturity, Fair Value	3,776	3,830
Tax Exempt State and Political Subdivisions Sales Tax Revenues [Member]
Tax-exempt state and political subdivisions	4,428	4,446
Unrealized Gains	0	0
Unrealized Losses	450	409
Debt Securities, Held-to-maturity, Fair Value	3,978	4,037
Tax Exempt State and Political Subdivisions Various Tax Revenues [Member]
Tax-exempt state and political subdivisions	5,403	5,425
Unrealized Gains	0	0
Unrealized Losses	649	536
Debt Securities, Held-to-maturity, Fair Value	4,754	4,889
Tax Exempt State and Political Subdivisions Other Revenues [Member]
Tax-exempt state and political subdivisions	3,405	3,423
Unrealized Gains	0	0
Unrealized Losses	227	196
Debt Securities, Held-to-maturity, Fair Value	$ 3,178	$ 3,227

[1] Derived from audited consolidated financial statements.