Note 5 - Debt Securities - Held to Maturity (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Tax-exempt state and political subdivisions	$ 94,227	$ 96,163
Unrealized Gains	0	0
Unrealized Losses	5,908	9,536
Debt Securities, Held-to-maturity, Fair Value	88,319	86,627
Tax Exempt State and Political Subdivisions General Obligations [Member]
Tax-exempt state and political subdivisions	68,966	70,401
Unrealized Gains	0	0
Unrealized Losses	4,029	6,480
Debt Securities, Held-to-maturity, Fair Value	64,937	63,921
Tax Exempt State and Political Subdivisions Water And Sewer Revenues [Member]
Tax-exempt state and political subdivisions	7,816	8,006
Unrealized Gains	0	0
Unrealized Losses	417	672
Debt Securities, Held-to-maturity, Fair Value	7,399	7,334
Tax Exempt State and Political Subdivisions Lease Revenues [Member]
Tax-exempt state and political subdivisions	4,151	4,234
Unrealized Gains	0	0
Unrealized Losses	321	534
Debt Securities, Held-to-maturity, Fair Value	3,830	3,700
Tax Exempt State and Political Subdivisions Sales Tax Revenues [Member]
Tax-exempt state and political subdivisions	4,446	4,515
Unrealized Gains	0	0
Unrealized Losses	409	689
Debt Securities, Held-to-maturity, Fair Value	4,037	3,826
Tax Exempt State and Political Subdivisions Various Tax Revenues [Member]
Tax-exempt state and political subdivisions	5,425	5,511
Unrealized Gains	0	0
Unrealized Losses	536	871
Debt Securities, Held-to-maturity, Fair Value	4,889	4,640
Tax Exempt State and Political Subdivisions Other Revenues [Member]
Tax-exempt state and political subdivisions	3,423	3,496
Unrealized Gains	0	0
Unrealized Losses	196	290
Debt Securities, Held-to-maturity, Fair Value	$ 3,227	$ 3,206