Note 5 - Debt Securities - Summary of Amortized Cost and Fair Value of Available-for-sale Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Debt securities, available for sale, amortized cost	$ 455,067	$ 398,643
Available for sale securities, unrealized gains	721	6,223
Available for sale securities, unrealized losses	50,587	3,763
Debt securities available for sale (at fair value)	405,201	401,103
US Government Corporations and Agencies Securities [Member]
Debt securities, available for sale, amortized cost	20,446	36,820
Available for sale securities, unrealized gains	83	169
Available for sale securities, unrealized losses	310	360
Debt securities available for sale (at fair value)	20,219	36,629
Government Sponsored Agencies [Member]
Debt securities, available for sale, amortized cost	55,184	61,646
Available for sale securities, unrealized gains	80	1,153
Available for sale securities, unrealized losses	3,808	588
Debt securities available for sale (at fair value)	51,456	62,211
Nongovernment Sponsored Agencies [Member]
Debt securities, available for sale, amortized cost	65,860	26,839
Available for sale securities, unrealized gains	48	26
Available for sale securities, unrealized losses	4,291	279
Debt securities available for sale (at fair value)	61,617	26,586
Taxable State and Political Subdivisions General Obligations [Member]
Debt securities, available for sale, amortized cost	82,410	78,627
Available for sale securities, unrealized gains	9	377
Available for sale securities, unrealized losses	19,924	1,323
Debt securities available for sale (at fair value)	62,495	77,681
Taxable State and Political Subdivisions Various Tax Revenues [Member]
Debt securities, available for sale, amortized cost	10,699	13,031
Available for sale securities, unrealized gains	0	218
Available for sale securities, unrealized losses	2,591	203
Debt securities available for sale (at fair value)	8,108	13,046
Taxable State and Political Subdivisions Water and Sewer Revenues [Member]
Debt securities, available for sale, amortized cost		9,839
Available for sale securities, unrealized gains		294
Available for sale securities, unrealized losses		0
Debt securities available for sale (at fair value)		10,133
Taxable State and Political Subdivisions Other Revenues [Member]
Debt securities, available for sale, amortized cost	29,044	9,291
Available for sale securities, unrealized gains	0	331
Available for sale securities, unrealized losses	6,580	9
Debt securities available for sale (at fair value)	22,464	9,613
Taxable State and Political Subdivisions Lease Revenues [Member]
Debt securities, available for sale, amortized cost		6,401
Available for sale securities, unrealized gains		215
Available for sale securities, unrealized losses		26
Debt securities available for sale (at fair value)		6,590
Corporate Debt Securities [Member]
Debt securities, available for sale, amortized cost	33,409	30,524
Available for sale securities, unrealized gains	44	78
Available for sale securities, unrealized losses	1,825	324
Debt securities available for sale (at fair value)	31,628	30,278
Taxable State and Political Subdivisions Income Tax Revenues [Member]
Debt securities, available for sale, amortized cost		6,487
Available for sale securities, unrealized gains		250
Available for sale securities, unrealized losses		3
Debt securities available for sale (at fair value)		6,734
Asset-Backed Securities [Member]
Debt securities, available for sale, amortized cost	20,009	24,873
Available for sale securities, unrealized gains	0	97
Available for sale securities, unrealized losses	533	87
Debt securities available for sale (at fair value)	19,476	24,883
Taxable State and Political Subdivisions Sales Tax Revenues [Member]
Debt securities, available for sale, amortized cost		6,909
Available for sale securities, unrealized gains		19
Available for sale securities, unrealized losses		99
Debt securities available for sale (at fair value)		6,829
Taxable Debt Securities [Member]
Debt securities, available for sale, amortized cost	317,061	318,440
Available for sale securities, unrealized gains	264	3,364
Available for sale securities, unrealized losses	39,862	3,431
Debt securities available for sale (at fair value)	277,463	318,373
Taxable State and Political Subdivisions Utility Revenues [Member]
Debt securities, available for sale, amortized cost		7,153
Available for sale securities, unrealized gains		137
Available for sale securities, unrealized losses		130
Debt securities available for sale (at fair value)		7,160
Tax Exempt State and Political Subdivisions General Obligations [Member]
Debt securities, available for sale, amortized cost	93,910	47,583
Available for sale securities, unrealized gains	281	1,526
Available for sale securities, unrealized losses	6,719	270
Debt securities available for sale (at fair value)	87,472	48,839
Tax Exempt State and Political Subdivisions Water And Sewer Revenues [Member]
Debt securities, available for sale, amortized cost	17,560	10,618
Available for sale securities, unrealized gains	120	375
Available for sale securities, unrealized losses	1,154	15
Debt securities available for sale (at fair value)	16,526	10,978
Tax Exempt State and Political Subdivisions Lease Revenues [Member]
Debt securities, available for sale, amortized cost	7,411	7,974
Available for sale securities, unrealized gains	47	553
Available for sale securities, unrealized losses	411	31
Debt securities available for sale (at fair value)	7,047	8,496
Tax Exempt State and Political Subdivisions Various Tax Revenues [Member]
Debt securities, available for sale, amortized cost	7,851
Available for sale securities, unrealized gains	0
Available for sale securities, unrealized losses	1,115
Debt securities available for sale (at fair value)	6,736
Tax Exempt State and Political Subdivisions Other Revenues [Member]
Debt securities, available for sale, amortized cost	11,274	14,028
Available for sale securities, unrealized gains	9	405
Available for sale securities, unrealized losses	1,326	16
Debt securities available for sale (at fair value)	9,957	14,417
Tax Exempt Debt Securities [Member]
Debt securities, available for sale, amortized cost	138,006	80,203
Available for sale securities, unrealized gains	457	2,859
Available for sale securities, unrealized losses	10,725	332
Debt securities available for sale (at fair value)	$ 127,738	$ 82,730