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Loans - Risk Category of Loans at Amortized Cost, by Portfolio Segment Based on Year of Origination (Detail) - USD ($) $ in Thousands | Sep. 30, 2025 | Dec. 31, 2024
--- | --- | ---
Financing Receivable, Credit Quality Indicator [Line Items] |  |
Grand Total | $ 2,658,275 | $ 2,560,795
Consumer Real Estate [Member] |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 | 41,227 | 40,400
2024 | 32,137 | 64,555
2023 | 54,878 | 80,069
2022 | 73,421 | 91,137
2021 | 85,851 | 75,461
Prior | 157,622 | 107,166
Term Total | 445,136 | 458,788
Revolving Loans Amortized Cost Basis | 76,772 | 61,352
Revolving Loans Converted to Term | 1,022 | 252
Grand Total | 522,930 | 520,392
Gross charge-offs - Prior |  | 13
Gross charge-offs - Term Total |  | 13
Gross charge-offs - Grand Total |  | 13
Consumer Real Estate [Member] | Pass [Member] |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 | 40,968 | 40,257
2024 | 31,813 | 64,316
2023 | 54,353 | 79,503
2022 | 72,918 | 89,800
2021 | 84,269 | 74,996
Prior | 155,908 | 106,007
Term Total | 440,229 | 454,879
Revolving Loans Amortized Cost Basis | 76,729 | 61,097
Revolving Loans Converted to Term | 882 | 237
Grand Total | 517,840 | 516,213
Consumer Real Estate [Member] | Special Mention [Member] |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2023 |  | 37
2022 |  | 551
2021 | 132 |
Prior | 49 | 119
Term Total | 181 | 707
Revolving Loans Amortized Cost Basis | 19 | 19
Grand Total | 200 | 726
Consumer Real Estate [Member] | Substandard [Member] |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 | 259 | 143
2024 | 324 | 239
2023 | 525 | 529
2022 | 503 | 786
2021 | 1,450 | 465
Prior | 1,665 | 1,040
Term Total | 4,726 | 3,202
Revolving Loans Amortized Cost Basis | 24 | 236
Revolving Loans Converted to Term | 140 | 15
Grand Total | 4,890 | 3,453
Agricultural Real Estate [Member] |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 | 22,991 | 29,513
2024 | 26,411 | 28,088
2023 | 25,619 | 34,840
2022 | 32,566 | 22,983
2021 | 22,020 | 23,639
Prior | 92,228 | 76,982
Term Total | 221,835 | 216,045
Revolving Loans Amortized Cost Basis | 88 | 92
Revolving Loans Converted to Term | 0 |
Grand Total | 221,923 | 216,137
Agricultural Real Estate [Member] | Pass [Member] |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 | 22,991 | 23,817
2024 | 21,521 | 28,088
2023 | 24,750 | 34,469
2022 | 31,689 | 22,983
2021 | 20,954 | 23,639
Prior | 91,857 | 76,964
Term Total | 213,762 | 209,960
Revolving Loans Amortized Cost Basis | 88 | 92
Grand Total | 213,850 | 210,052
Agricultural Real Estate [Member] | Special Mention [Member] |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2022 | 32 |
Prior | 283 | 13
Term Total | 315 | 13
Grand Total | 315 | 13
Agricultural Real Estate [Member] | Substandard [Member] |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 |  | 5,696
2024 | 4,890 |
2023 | 869 | 371
2022 | 845 |
2021 | 1,066 |
Prior | 88 | 5
Term Total | 7,758 | 6,072
Grand Total | 7,758 | 6,072
Agricultural [Member] |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 | 21,487 | 14,915
2024 | 9,596 | 10,534
2023 | 7,569 | 14,381
2022 | 10,217 | 5,624
2021 | 3,923 | 3,233
Prior | 4,863 | 3,911
Term Total | 57,655 | 52,598
Revolving Loans Amortized Cost Basis | 121,250 | 99,783
Revolving Loans Converted to Term | 794 |
Grand Total | 179,699 | 152,381
Agricultural [Member] | Pass [Member] |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 | 19,076 | 14,915
2024 | 9,563 | 10,500
2023 | 7,462 | 14,381
2022 | 9,855 | 5,616
2021 | 3,902 | 3,204
Prior | 4,863 | 3,911
Term Total | 54,721 | 52,527
Revolving Loans Amortized Cost Basis | 106,985 | 98,283
Revolving Loans Converted to Term | 794 |
Grand Total | 162,500 | 150,810
Agricultural [Member] | Special Mention [Member] |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 | 2,011 |
2024 |  | 13
2022 | 305 | 8
2021 | 21 |
Term Total | 2,337 | 21
Revolving Loans Amortized Cost Basis | 12,545 | 30
Grand Total | 14,882 | 51
Agricultural [Member] | Substandard [Member] |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 | 400 |
2024 | 33 | 21
2023 | 107 |
2022 | 57 |
2021 |  | 29
Term Total | 597 | 50
Revolving Loans Amortized Cost Basis | 1,720 | 1,470
Grand Total | 2,317 | 1,520
Commercial Real Estate [Member] |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 | 165,754 | 128,608
2024 | 144,051 | 234,491
2023 | 223,844 | 425,696
2022 | 401,198 | 218,309
2021 | 209,281 | 111,787
Prior | 208,562 | 189,570
Term Total | 1,352,690 | 1,308,461
Revolving Loans Amortized Cost Basis | 0 |
Revolving Loans Converted to Term | 0 |
Grand Total | 1,352,690 | 1,308,461
Gross charge-offs - Prior |  | 15
Gross charge-offs - Term Total |  | 15
Gross charge-offs - Grand Total |  | 15
Commercial Real Estate [Member] | Pass [Member] |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 | 162,678 | 128,608
2024 | 144,051 | 200,192
2023 | 174,606 | 413,106
2022 | 374,782 | 218,309
2021 | 195,265 | 110,435
Prior | 198,130 | 188,239
Term Total | 1,249,512 | 1,258,889
Grand Total | 1,249,512 | 1,258,889
Commercial Real Estate [Member] | Special Mention [Member] |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 | 1,345 |
2023 | 15,551 | 12,590
2022 | 24,527 |
2021 | 12,619 | 1,352
Prior | 3,716 | 753
Term Total | 57,758 | 14,695
Grand Total | 57,758 | 14,695
Commercial Real Estate [Member] | Substandard [Member] |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 | 1,731 |
2024 |  | 34,299
2023 | 33,687 |
2022 | 1,889 |
2021 | 1,397 |
Prior | 6,716 | 578
Term Total | 45,420 | 34,877
Grand Total | 45,420 | 34,877
Commercial & Industrial [Member] |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 | 32,600 | 31,972
2024 | 27,011 | 55,066
2023 | 42,741 | 39,694
2022 | 31,064 | 15,235
2021 | 12,035 | 13,506
Prior | 8,919 | 1,738
Term Total | 154,370 | 157,211
Revolving Loans Amortized Cost Basis | 141,055 | 117,386
Revolving Loans Converted to Term | 390 | 222
Grand Total | 295,815 | 274,819
Gross charge-offs - fiscal year 2022 | 26 |
Gross charge-offs - fiscal year 2021 |  | 101
Gross charge-offs - Term Total | 26 | 101
Gross charge-offs - Revolving Loans Converted to Term |  | 5
Gross charge-offs - Grand Total | 26 | 106
Commercial & Industrial [Member] | Pass [Member] |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 | 32,600 | 31,933
2024 | 26,840 | 54,581
2023 | 42,252 | 39,665
2022 | 31,040 | 15,047
2021 | 11,838 | 13,480
Prior | 8,586 | 1,294
Term Total | 153,156 | 156,000
Revolving Loans Amortized Cost Basis | 128,248 | 113,446
Revolving Loans Converted to Term | 78 | 222
Grand Total | 281,482 | 269,668
Commercial & Industrial [Member] | Special Mention [Member] |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2024 |  | 137
2023 | 207 |
2022 |  | 188
2021 | 171 | 26
Prior | 333 | 416
Term Total | 711 | 767
Revolving Loans Amortized Cost Basis | 9,117 | 459
Revolving Loans Converted to Term | 312 |
Grand Total | 10,140 | 1,226
Commercial & Industrial [Member] | Substandard [Member] |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 |  | 39
2024 | 171 | 348
2023 | 282 | 29
2022 | 24 |
2021 | 26 |
Prior |  | 28
Term Total | 503 | 444
Revolving Loans Amortized Cost Basis | 3,493 | 3,481
Grand Total | 3,996 | 3,925
Commercial & Industrial [Member] | Doubtful [Member] |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
Revolving Loans Amortized Cost Basis | 197 |
Grand Total | 197 |
Consumer [Member] |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
Grand Total | 61,132 | 63,627
Consumer [Member] | Payment Performance [Member] |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 | 19,806 | 13,477
2024 | 9,647 | 13,521
2023 | 9,020 | 27,304
2022 | 17,749 | 5,952
2021 | 3,278 | 2,314
Prior | 1,163 | 582
Term Total | 60,663 | 63,150
Revolving Loans Amortized Cost Basis | 469 | 477
Grand Total | 61,132 | 63,627
Gross charge-offs - fiscal year 2025 | 154 | 201
Gross charge-offs - fiscal year 2024 | 55 | 69
Gross charge-offs - fiscal year 2023 | 128 | 62
Gross charge-offs - fiscal year 2022 | 162 | 14
Gross charge-offs - fiscal year 2021 | 61 |
Gross charge-offs - Prior | 1 |
Gross charge-offs - Term Total | 561 | 346
Gross charge-offs - Grand Total | 561 | 346
Consumer [Member] | Performing [Member] | Payment Performance [Member] |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 | 19,806 | 13,437
2024 | 9,647 | 13,521
2023 | 8,998 | 27,264
2022 | 17,733 | 5,917
2021 | 3,261 | 2,310
Prior | 1,158 | 582
Term Total | 60,603 | 63,031
Revolving Loans Amortized Cost Basis | 469 | 477
Grand Total | 61,072 | 63,508
Consumer [Member] | Nonperforming [Member] | Payment Performance [Member] |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 |  | 40
2023 | 22 | 40
2022 | 16 | 35
2021 | 17 | 4
Prior | 5 |
Term Total | 60 | 119
Grand Total | 60 | 119
Other Loan [Member] |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 | 584 |
2024 | 0 |
2023 | 0 |
2022 | 0 | 15,829
2021 | 15,491 | 5,068
Prior | 8,011 | 4,081
Term Total | 24,086 | 24,978
Revolving Loans Amortized Cost Basis | 0 |
Revolving Loans Converted to Term | 0 |
Grand Total | 24,086 | 24,978
Other Loan [Member] | Pass [Member] |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 | 584 |
2022 |  | 15,829
2021 | 15,491 | 5,068
Prior | 8,011 | 4,081
Term Total | 24,086 | 24,978
Grand Total | $ 24,086 | $ 24,978

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