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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

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