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Note 3 - Securities (Tables) | 12 Months Ended
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Dec. 31, 2022
Notes Tables |
Debt Securities, Available-for-Sale [Table Text Block] |
|  | December 31, 2022 |
Available for sale: |  | 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 |
|  | December 31, 2021 |
Available for sale: |  | Amortized Cost |  |  | Gross Unrealized Gains |  |  | Gross Unrealized Losses |  |  | Fair Value |
U.S. government agencies and corporations |  | $ | 279,934 |  |  | $ | 2,795 |  |  | $ | 4,710 |  |  | $ | 278,019 |
States and political subdivisions |  |  | 195,365 |  |  |  | 5,314 |  |  |  | 2,007 |  |  |  | 198,672 |
Mortgage-backed securities |  |  | 204,164 |  |  |  | 2,323 |  |  |  | 313 |  |  |  | 206,174 |
Corporate debt securities |  |  | 3,004 |  |  |  | 248 |  |  |  | 37 |  |  |  | 3,215 |
Total securities available for sale |  | $ | 682,467 |  |  | $ | 10,680 |  |  | $ | 7,067 |  |  | $ | 686,080 |
Investments Classified by Contractual Maturity Date [Table Text Block] |
|  | December 31, 2022 |
Available for sale: |  | Amortized Cost |  |  | Fair Value |
Due in one year or less |  | $ | 2,779 |  |  | $ | 2,738 |
Due after one year through five years |  |  | 139,168 |  |  |  | 129,798 |
Due after five years through ten years |  |  | 328,812 |  |  |  | 279,880 |
Due after ten years |  |  | 289,158 |  |  |  | 244,436 |
Total securities available for sale |  | $ | 759,917 |  |  | $ | 656,852 |
Schedule of Temporary Impairment Losses, Investments [Table Text Block] |
|  | 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 |
|  | December 31, 2021 |
|  | Less Than 12 Months |  |  | 12 Months or More |
|  | Fair Value |  |  | Unrealized Loss |  |  | Fair Value |  |  | Unrealized Loss |
U.S. Government agencies and corporations |  | $ | 201,650 |  |  | $ | 3,530 |  |  | $ | 26,792 |  |  | $ | 1,180 |
State and political subdivisions |  |  | 50,659 |  |  |  | 1,214 |  |  |  | 20,542 |  |  |  | 793 |
Mortgage-backed securities |  |  | 13,139 |  |  |  | 141 |  |  |  | 4,665 |  |  |  | 172 |
Corporate debt securities |  |  | 966 |  |  |  | 37 |  |  |  | - |  |  |  | - |
Total temporarily impaired securities |  | $ | 266,414 |  |  | $ | 4,922 |  |  | $ | 51,999 |  |  | $ | 2,145 |
Schedule of Realized Gain (Loss) on Called Securities [Table Text Block] |
|  | For the year ended December 31, 2021 |
|  | Proceeds |  |  | Book Value |  |  | Gross Gain |  |  | Gross Loss |  |  | Net Gain |
Available for sale |  | $ | 20,377 |  |  | $ | 20,371 |  |  | $ | 6 |  |  | $ | - |  |  | $ | 6 |

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