Note 2 - Securities - Amortized Cost, Gross Unrealized Gains and Losses, and Estimated Fair Value of Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Investment securities available for sale, amortized cost	$ 341,011	$ 333,950
Securities available for sale, gross unrealized gains	287	0
Securities available for sale, gross unrealized losses	(30,438)	(38,327)
Investment securities available for sale, at fair value (amortized cost of $341,011 and $333,950, respectively)	310,860	295,623
Securities available for sale, allowance for credit losses	0	0
US States and Political Subdivisions Debt Securities [Member]
Investment securities available for sale, amortized cost	93,573	102,998
Securities available for sale, gross unrealized gains	0	0
Securities available for sale, gross unrealized losses	(12,210)	(15,237)
Investment securities available for sale, at fair value (amortized cost of $341,011 and $333,950, respectively)	81,363	87,761
Securities available for sale, allowance for credit losses	0	0
US Government Agencies Debt Securities [Member]
Investment securities available for sale, amortized cost	13,312	11,847
Securities available for sale, gross unrealized gains	16	0
Securities available for sale, gross unrealized losses	(32)	(65)
Investment securities available for sale, at fair value (amortized cost of $341,011 and $333,950, respectively)	13,296	11,782
Securities available for sale, allowance for credit losses	0	0
Corporate Issued Asset-backed Securities [Member]
Investment securities available for sale, amortized cost	16,364	5,370
Securities available for sale, gross unrealized gains	48	0
Securities available for sale, gross unrealized losses	(21)	(84)
Investment securities available for sale, at fair value (amortized cost of $341,011 and $333,950, respectively)	16,391	5,286
Securities available for sale, allowance for credit losses	0	0
Corporate Debt Securities [Member]
Investment securities available for sale, amortized cost	58,131	56,515
Securities available for sale, gross unrealized gains	0	0
Securities available for sale, gross unrealized losses	(4,073)	(5,061)
Investment securities available for sale, at fair value (amortized cost of $341,011 and $333,950, respectively)	54,058	51,454
Securities available for sale, allowance for credit losses	0	0
US Small Business Administration Securities [Member]
Investment securities available for sale, amortized cost	9,268
Securities available for sale, gross unrealized gains	56
Securities available for sale, gross unrealized losses	(7)
Investment securities available for sale, at fair value (amortized cost of $341,011 and $333,950, respectively)	9,317
Securities available for sale, allowance for credit losses	0
Mortgage-Backed Security, Issued by US Government-Sponsored Enterprise [Member]
Investment securities available for sale, amortized cost	88,822	75,665
Securities available for sale, gross unrealized gains	167	0
Securities available for sale, gross unrealized losses	(10,440)	(12,418)
Investment securities available for sale, at fair value (amortized cost of $341,011 and $333,950, respectively)	78,549	63,247
Securities available for sale, allowance for credit losses	0	0
Mortgage-Backed Securities, Issued by Private Enterprises [Member]
Investment securities available for sale, amortized cost	61,541	81,555
Securities available for sale, gross unrealized gains	0	0
Securities available for sale, gross unrealized losses	(3,655)	(5,462)
Investment securities available for sale, at fair value (amortized cost of $341,011 and $333,950, respectively)	57,886	76,093
Securities available for sale, allowance for credit losses	$ 0	$ 0

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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