Note 5 - Debt Securities - Schedule of Unrealized Loss on Investments (Details) $ in Thousands	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Number of Securities in Loss Positions	310	157
Estimated Fair Value, Less than 12 Months	$ 173,827	$ 169,460
Unrealized Loss, Less than 12 Months	10,906	2,926
Estimated Fair Value, 12 Months or More	173,131	39,837
Unrealized Loss, 12 Months or More	39,681	837
Estimated Fair Value, Total	346,958	209,297
Unrealized Loss, Total	$ 50,587	$ 3,763
US Government Corporations and Agencies Securities [Member]
Number of Securities in Loss Positions	28	41
Estimated Fair Value, Less than 12 Months	$ 8,012	$ 6,630
Unrealized Loss, Less than 12 Months	99	23
Estimated Fair Value, 12 Months or More	9,577	21,061
Unrealized Loss, 12 Months or More	211	337
Estimated Fair Value, Total	17,589	27,691
Unrealized Loss, Total	$ 310	$ 360
Government Sponsored Agencies [Member]
Number of Securities in Loss Positions	58	19
Estimated Fair Value, Less than 12 Months	$ 21,831	$ 19,828
Unrealized Loss, Less than 12 Months	1,104	376
Estimated Fair Value, 12 Months or More	19,459	6,886
Unrealized Loss, 12 Months or More	2,704	212
Estimated Fair Value, Total	41,290	26,714
Unrealized Loss, Total	$ 3,808	$ 588
Nongovernment Sponsored Agencies [Member]
Number of Securities in Loss Positions	27	6
Estimated Fair Value, Less than 12 Months	$ 35,727	$ 4,345
Unrealized Loss, Less than 12 Months	2,974	61
Estimated Fair Value, 12 Months or More	10,041	7,591
Unrealized Loss, 12 Months or More	1,317	218
Estimated Fair Value, Total	45,768	11,936
Unrealized Loss, Total	$ 4,291	$ 279
Taxable State and Political Subdivisions General Obligations [Member]
Number of Securities in Loss Positions	56	41
Estimated Fair Value, Less than 12 Months	$ 11,258	$ 62,543
Unrealized Loss, Less than 12 Months	1,476	1,286
Estimated Fair Value, 12 Months or More	49,858	1,055
Unrealized Loss, 12 Months or More	18,448	37
Estimated Fair Value, Total	61,116	63,598
Unrealized Loss, Total	$ 19,924	$ 1,323
Taxable State and Political Subdivisions Various Tax Revenues [Member]
Number of Securities in Loss Positions	7	5
Estimated Fair Value, Less than 12 Months	$ 1,352	$ 8,389
Unrealized Loss, Less than 12 Months	276	203
Estimated Fair Value, 12 Months or More	6,756	0
Unrealized Loss, 12 Months or More	2,315	0
Estimated Fair Value, Total	8,108	8,389
Unrealized Loss, Total	$ 2,591	$ 203
Taxable State and Political Subdivisions Lease Revenues [Member]
Number of Securities in Loss Positions		2
Estimated Fair Value, Less than 12 Months		$ 1,564
Unrealized Loss, Less than 12 Months		14
Estimated Fair Value, 12 Months or More		494
Unrealized Loss, 12 Months or More		12
Estimated Fair Value, Total		2,058
Unrealized Loss, Total		$ 26
Taxable State and Political Subdivisions Other Revenues [Member]
Number of Securities in Loss Positions	23	1
Estimated Fair Value, Less than 12 Months	$ 6,361	$ 744
Unrealized Loss, Less than 12 Months	1,040	9
Estimated Fair Value, 12 Months or More	16,103	0
Unrealized Loss, 12 Months or More	5,540	0
Estimated Fair Value, Total	22,464	744
Unrealized Loss, Total	$ 6,580	$ 9
Taxable State and Political Subdivisions Income Tax Revenues [Member]
Number of Securities in Loss Positions		1
Estimated Fair Value, Less than 12 Months		$ 721
Unrealized Loss, Less than 12 Months		3
Estimated Fair Value, 12 Months or More		0
Unrealized Loss, 12 Months or More		0
Estimated Fair Value, Total		721
Unrealized Loss, Total		$ 3
Corporate Debt Securities [Member]
Number of Securities in Loss Positions	20	10
Estimated Fair Value, Less than 12 Months	$ 8,308	$ 10,534
Unrealized Loss, Less than 12 Months	591	314
Estimated Fair Value, 12 Months or More	13,072	990
Unrealized Loss, 12 Months or More	1,234	10
Estimated Fair Value, Total	21,380	11,524
Unrealized Loss, Total	$ 1,825	$ 324
Taxable State and Political Subdivisions Sales Tax Revenues [Member]
Number of Securities in Loss Positions		2
Estimated Fair Value, Less than 12 Months		$ 6,052
Unrealized Loss, Less than 12 Months		99
Estimated Fair Value, 12 Months or More		0
Unrealized Loss, 12 Months or More		0
Estimated Fair Value, Total		6,052
Unrealized Loss, Total		$ 99
Asset-Backed Securities [Member]
Number of Securities in Loss Positions	13	8
Estimated Fair Value, Less than 12 Months	$ 11,680	$ 10,522
Unrealized Loss, Less than 12 Months	277	86
Estimated Fair Value, 12 Months or More	7,796	751
Unrealized Loss, 12 Months or More	256	1
Estimated Fair Value, Total	19,476	11,273
Unrealized Loss, Total	$ 533	$ 87
Taxable State and Political Subdivisions Utility Revenues [Member]
Number of Securities in Loss Positions		3
Estimated Fair Value, Less than 12 Months		$ 5,175
Unrealized Loss, Less than 12 Months		130
Estimated Fair Value, 12 Months or More		0
Unrealized Loss, 12 Months or More		0
Estimated Fair Value, Total		5,175
Unrealized Loss, Total		$ 130
Tax Exempt State and Political Subdivisions General Obligations [Member]
Number of Securities in Loss Positions	52	13
Estimated Fair Value, Less than 12 Months	$ 50,671	$ 25,555
Unrealized Loss, Less than 12 Months	1,823	261
Estimated Fair Value, 12 Months or More	26,062	853
Unrealized Loss, 12 Months or More	4,896	9
Estimated Fair Value, Total	76,733	26,408
Unrealized Loss, Total	$ 6,719	$ 270
Tax Exempt State and Political Subdivisions Water And Sewer Revenues [Member]
Number of Securities in Loss Positions	13	1
Estimated Fair Value, Less than 12 Months	$ 8,800	$ 904
Unrealized Loss, Less than 12 Months	403	15
Estimated Fair Value, 12 Months or More	4,471	0
Unrealized Loss, 12 Months or More	751	0
Estimated Fair Value, Total	13,271	904
Unrealized Loss, Total	$ 1,154	$ 15
Tax Exempt State and Political Subdivisions Lease Revenues [Member]
Number of Securities in Loss Positions	2	1
Estimated Fair Value, Less than 12 Months	$ 3,330	$ 2,396
Unrealized Loss, Less than 12 Months	11	31
Estimated Fair Value, 12 Months or More	1,985	0
Unrealized Loss, 12 Months or More	400	0
Estimated Fair Value, Total	5,315	2,396
Unrealized Loss, Total	$ 411	$ 31
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
Tax Exempt State and Political Subdivisions Other Revenues [Member]
Number of Securities in Loss Positions	7	3
Estimated Fair Value, Less than 12 Months	$ 2,900	$ 3,558
Unrealized Loss, Less than 12 Months	393	15
Estimated Fair Value, 12 Months or More	4,812	156
Unrealized Loss, 12 Months or More	933	1
Estimated Fair Value, Total	7,712	3,714
Unrealized Loss, Total	$ 1,326	$ 16