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Note 3 - Securities (Tables) | 12 Months Ended
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Dec. 31, 2023
Notes Tables |
Debt Securities, Available-for-Sale [Table Text Block] |
December 31, 2023 |  | Amortized Cost |  |  | Gross Unrealized Gains |  |  | Gross Unrealized Losses |  |  | Fair Value |
U.S. government agencies and corporations |  | $ | 353,904 |  |  | $ | - |  |  | $ | 42,060 |  |  | $ | 311,844 |
States and political subdivisions |  |  | 179,507 |  |  |  | - |  |  |  | 29,614 |  |  |  | 149,893 |
Mortgage-backed securities |  |  | 156,875 |  |  |  | - |  |  |  | 6,724 |  |  |  | 150,151 |
Corporate debt securities |  |  | 6,504 |  |  |  | - |  |  |  | 754 |  |  |  | 5,750 |
U.S. treasury |  |  | 996 |  |  |  | - |  |  |  | 33 |  |  |  | 963 |
Total securities available for sale |  | $ | 697,786 |  |  | $ | - |  |  | $ | 79,185 |  |  | $ | 618,601 |
December 31, 2022 |  | Amortized Cost |  |  | Gross Unrealized Gains |  |  | Gross Unrealized Losses |  |  | Fair Value |
U.S. government agencies and corporations |  | $ | 391,538 |  |  | $ | 39 |  |  | $ | 55,002 |  |  | $ | 336,575 |
States and political subdivisions |  |  | 190,192 |  |  |  | 26 |  |  |  | 38,018 |  |  |  | 152,200 |
Mortgage-backed securities |  |  | 170,694 |  |  |  | 22 |  |  |  | 9,239 |  |  |  | 161,477 |
Corporate debt securities |  |  | 6,501 |  |  |  | - |  |  |  | 837 |  |  |  | 5,664 |
U.S. treasury |  |  | 992 |  |  |  | - |  |  |  | 56 |  |  |  | 936 |
Total securities available for sale |  | $ | 759,917 |  |  | $ | 87 |  |  | $ | 103,152 |  |  | $ | 656,852 |
Investments Classified by Contractual Maturity Date [Table Text Block] |
December 31, 2023 |  | Amortized Cost |  |  | Fair Value |
Due in one year or less |  | $ | 3,795 |  |  | $ | 3,748 |
Due after one year through five years |  |  | 178,297 |  |  |  | 166,386 |
Due after five years through ten years |  |  | 277,155 |  |  |  | 238,409 |
Due after ten years |  |  | 238,539 |  |  |  | 210,058 |
Total securities available for sale |  | $ | 697,786 |  |  | $ | 618,601 |
Gain (Loss) on Securities [Table Text Block] |
December 31, 2023 |  | Less Than 12 Months |  |  | 12 Months or More |
|  | Fair Value |  |  | Unrealized Loss |  |  | Fair Value |  |  | Unrealized Loss |
U.S. government agencies and corporations |  | $ | - |  |  | $ | - |  |  | $ | 311,844 |  |  | $ | 42,060 |
State and political subdivisions |  |  | 884 |  |  |  | 1 |  |  |  | 148,763 |  |  |  | 29,613 |
Mortgage-backed securities |  |  | 1,616 |  |  |  | 26 |  |  |  | 147,922 |  |  |  | 6,698 |
Corporate debt securities |  |  | - |  |  |  | - |  |  |  | 5,750 |  |  |  | 754 |
U.S. treasury |  |  | - |  |  |  | - |  |  |  | 963 |  |  |  | 33 |
Total temporarily impaired securities |  | $ | 2,500 |  |  | $ | 27 |  |  | $ | 615,242 |  |  | $ | 79,158 |
December 31, 2022 |  | Less Than 12 Months |  |  | 12 Months or More |
|  | Fair Value |  |  | Unrealized Loss |  |  | Fair Value |  |  | Unrealized Loss |
U.S. Government agencies and corporations |  | $ | 144,574 |  |  | $ | 12,699 |  |  | $ | 190,950 |  |  | $ | 42,303 |
State and political subdivisions |  |  | 94,657 |  |  |  | 18,373 |  |  |  | 52,134 |  |  |  | 19,645 |
Mortgage-backed securities |  |  | 144,198 |  |  |  | 7,326 |  |  |  | 15,165 |  |  |  | 1,913 |
Corporate debt securities |  |  | 4,843 |  |  |  | 655 |  |  |  | 821 |  |  |  | 182 |
U.S. treasury |  |  | 936 |  |  |  | 56 |  |  |  | - |  |  |  | - |
Total temporarily impaired securities |  | $ | 389,208 |  |  | $ | 39,109 |  |  | $ | 259,070 |  |  | $ | 64,043 |
Schedule of Realized Gain (Loss) on Called Securities [Table Text Block] |
|  | For the Year Ended December 31, 2023 |
|  | Proceeds |  |  | Book Value |  |  | Gross Gain |  |  | Gross Loss |  |  | Net Loss |
Available for sale |  | $ | 43,518 |  |  | $ | 46,850 |  |  | $ | 137 |  |  | $ | 3,469 |  |  | $ | 3,332 |

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