Note 5 - Debt Securities - Schedule of Unrealized Loss on Investments (Details) $ in Thousands	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Number of Securities in Loss Positions	385	310
Estimated Fair Value, Less than 12 Months	$ 148,825	$ 173,827
Unrealized Loss, Less than 12 Months	3,912	10,906
Estimated Fair Value, 12 Months or More	264,467	173,131
Unrealized Loss, 12 Months or More	36,056	39,681
Estimated Fair Value, Total	413,292	346,958
Unrealized Loss, Total	$ 39,968	$ 50,587
US Government Corporations and Agencies Securities [Member]
Number of Securities in Loss Positions	39	28
Estimated Fair Value, Less than 12 Months	$ 11,809	$ 8,012
Unrealized Loss, Less than 12 Months	287	99
Estimated Fair Value, 12 Months or More	9,329	9,577
Unrealized Loss, 12 Months or More	221	211
Estimated Fair Value, Total	21,138	17,589
Unrealized Loss, Total	$ 508	$ 310
Government Sponsored Agencies [Member]
Number of Securities in Loss Positions	133	58
Estimated Fair Value, Less than 12 Months	$ 68,815	$ 21,831
Unrealized Loss, Less than 12 Months	1,528	1,104
Estimated Fair Value, 12 Months or More	32,902	19,459
Unrealized Loss, 12 Months or More	3,343	2,704
Estimated Fair Value, Total	101,717	41,290
Unrealized Loss, Total	$ 4,871	$ 3,808
Nongovernment Sponsored Agencies [Member]
Number of Securities in Loss Positions	35	27
Estimated Fair Value, Less than 12 Months	$ 27,804	$ 35,727
Unrealized Loss, Less than 12 Months	1,493	2,974
Estimated Fair Value, 12 Months or More	40,274	10,041
Unrealized Loss, 12 Months or More	3,010	1,317
Estimated Fair Value, Total	68,078	45,768
Unrealized Loss, Total	$ 4,503	$ 4,291
Taxable State and Political Subdivisions General Obligations [Member]
Number of Securities in Loss Positions	54	56
Estimated Fair Value, Less than 12 Months	$ 0	$ 11,258
Unrealized Loss, Less than 12 Months	0	1,476
Estimated Fair Value, 12 Months or More	63,336	49,858
Unrealized Loss, 12 Months or More	14,995	18,448
Estimated Fair Value, Total	63,336	61,116
Unrealized Loss, Total	$ 14,995	$ 19,924
Taxable State and Political Subdivisions Various Tax Revenues [Member]
Number of Securities in Loss Positions	7	7
Estimated Fair Value, Less than 12 Months	$ 0	$ 1,352
Unrealized Loss, Less than 12 Months	0	276
Estimated Fair Value, 12 Months or More	8,558	6,756
Unrealized Loss, 12 Months or More	2,107	2,315
Estimated Fair Value, Total	8,558	8,108
Unrealized Loss, Total	$ 2,107	$ 2,591
Taxable State and Political Subdivisions Other Revenues [Member]
Number of Securities in Loss Positions	21	23
Estimated Fair Value, Less than 12 Months	$ 1,530	$ 6,361
Unrealized Loss, Less than 12 Months	56	1,040
Estimated Fair Value, 12 Months or More	18,854	16,103
Unrealized Loss, 12 Months or More	4,726	5,540
Estimated Fair Value, Total	20,384	22,464
Unrealized Loss, Total	$ 4,782	$ 6,580
Corporate Debt Securities [Member]
Number of Securities in Loss Positions	21	20
Estimated Fair Value, Less than 12 Months	$ 6,758	$ 8,308
Unrealized Loss, Less than 12 Months	341	591
Estimated Fair Value, 12 Months or More	18,310	13,072
Unrealized Loss, 12 Months or More	1,422	1,234
Estimated Fair Value, Total	25,068	21,380
Unrealized Loss, Total	$ 1,763	$ 1,825
Asset-Backed Securities [Member]
Number of Securities in Loss Positions	17	13
Estimated Fair Value, Less than 12 Months	$ 23,823	$ 11,680
Unrealized Loss, Less than 12 Months	110	277
Estimated Fair Value, 12 Months or More	9,961	7,796
Unrealized Loss, 12 Months or More	154	256
Estimated Fair Value, Total	33,784	19,476
Unrealized Loss, Total	$ 264	$ 533
Tax Exempt State and Political Subdivisions General Obligations [Member]
Number of Securities in Loss Positions	39	52
Estimated Fair Value, Less than 12 Months	$ 7,479	$ 50,671
Unrealized Loss, Less than 12 Months	69	1,823
Estimated Fair Value, 12 Months or More	43,626	26,062
Unrealized Loss, 12 Months or More	3,647	4,896
Estimated Fair Value, Total	51,105	76,733
Unrealized Loss, Total	$ 3,716	$ 6,719
Tax Exempt State and Political Subdivisions Other Revenues [Member]
Number of Securities in Loss Positions	19	7
Estimated Fair Value, Less than 12 Months	$ 807	$ 2,900
Unrealized Loss, Less than 12 Months	28	393
Estimated Fair Value, 12 Months or More	19,317	4,812
Unrealized Loss, 12 Months or More	2,431	933
Estimated Fair Value, Total	20,124	7,712
Unrealized Loss, Total	$ 2,459	$ 1,326
Tax Exempt State and Political Subdivisions Water And Sewer Revenues [Member]
Number of Securities in Loss Positions		13
Estimated Fair Value, Less than 12 Months		$ 8,800
Unrealized Loss, Less than 12 Months		403
Estimated Fair Value, 12 Months or More		4,471
Unrealized Loss, 12 Months or More		751
Estimated Fair Value, Total		13,271
Unrealized Loss, Total		$ 1,154
Tax Exempt State and Political Subdivisions Lease Revenues [Member]
Number of Securities in Loss Positions		2
Estimated Fair Value, Less than 12 Months		$ 3,330
Unrealized Loss, Less than 12 Months		11
Estimated Fair Value, 12 Months or More		1,985
Unrealized Loss, 12 Months or More		400
Estimated Fair Value, Total		5,315
Unrealized Loss, Total		$ 411
Tax Exempt State and Political Subdivisions Various Tax Revenues [Member]
Number of Securities in Loss Positions		4
Estimated Fair Value, Less than 12 Months		$ 3,597
Unrealized Loss, Less than 12 Months		439
Estimated Fair Value, 12 Months or More		3,139
Unrealized Loss, 12 Months or More		676
Estimated Fair Value, Total		6,736
Unrealized Loss, Total		$ 1,115