v3.26.1
Loans - Contractual Aging at Amortized Cost in Past Due Loans by Portfolio Segment (Detail) - USD ($)
$ in Thousands
Jun. 30, 2026
Dec. 31, 2025
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Total Past Due $ 2,705,886 $ 2,713,470
Total Financing Receivables 2,704,467 2,711,959
30 to 59 Days Past Due [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Total Past Due 3,611 4,306
60 to 89 Days Past Due [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Total Past Due 1,041 2,398
Greater Than 90 Days [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Total Past Due 4,608 1,170
Past Due [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Total Past Due 9,260 7,874
Current [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Total Past Due 2,695,207 2,704,085
Consumer Real Estate [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Total Past Due 533,438 526,439
Total Financing Receivables 534,112 527,043
Consumer Real Estate [Member] | 30 to 59 Days Past Due [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Total Past Due 2,416 3,536
Consumer Real Estate [Member] | 60 to 89 Days Past Due [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Total Past Due 365 919
Consumer Real Estate [Member] | Greater Than 90 Days [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Total Past Due 180 766
Consumer Real Estate [Member] | Past Due [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Total Past Due 2,961 5,221
Consumer Real Estate [Member] | Current [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Total Past Due 531,151 521,822
Agricultural Real Estate [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Total Past Due 208,223 217,034
Total Financing Receivables 208,016 216,830
Agricultural Real Estate [Member] | 30 to 59 Days Past Due [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Total Past Due 413 516
Agricultural Real Estate [Member] | 60 to 89 Days Past Due [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Total Past Due 460 0
Agricultural Real Estate [Member] | Greater Than 90 Days [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Total Past Due 4,252 130
Agricultural Real Estate [Member] | Past Due [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Total Past Due 5,125 646
Agricultural Real Estate [Member] | Current [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Total Past Due 202,891 216,184
Agricultural [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Total Past Due 244,611 218,050
Total Financing Receivables 244,959 218,345
Agricultural [Member] | 30 to 59 Days Past Due [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Total Past Due 205 0
Agricultural [Member] | 60 to 89 Days Past Due [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Total Past Due 50 1,444
Agricultural [Member] | Greater Than 90 Days [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Total Past Due 110 50
Agricultural [Member] | Past Due [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Total Past Due 365 1,494
Agricultural [Member] | Current [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Total Past Due 244,594 216,851
Commercial Real Estate [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Total Past Due 1,308,600 1,355,571
Total Financing Receivables 1,306,154 1,353,019
Commercial Real Estate [Member] | 30 to 59 Days Past Due [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Total Past Due 0 56
Commercial Real Estate [Member] | 60 to 89 Days Past Due [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Total Past Due 0 0
Commercial Real Estate [Member] | Greater Than 90 Days [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Total Past Due 0 141
Commercial Real Estate [Member] | Past Due [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Total Past Due 0 197
Commercial Real Estate [Member] | Current [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Total Past Due 1,306,154 1,352,822
Commercial and Industrial [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Total Financing Receivables 337,126 314,096
Commercial and Industrial [Member] | 30 to 59 Days Past Due [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Total Past Due 474 0
Commercial and Industrial [Member] | 60 to 89 Days Past Due [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Total Past Due 140 0
Commercial and Industrial [Member] | Greater Than 90 Days [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Total Past Due 0 0
Commercial and Industrial [Member] | Past Due [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Total Past Due 614 0
Commercial and Industrial [Member] | Current [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Total Past Due 336,512 314,096
Consumer [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Total Past Due 50,953 58,838
Total Financing Receivables 51,526 59,493
Consumer [Member] | 30 to 59 Days Past Due [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Total Past Due 103 198
Consumer [Member] | 60 to 89 Days Past Due [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Total Past Due 26 35
Consumer [Member] | Greater Than 90 Days [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Total Past Due 66 83
Consumer [Member] | Past Due [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Total Past Due 195 316
Consumer [Member] | Current [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Total Past Due 51,331 59,177
Other Loan [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Total Past Due 22,574 23,133
Total Financing Receivables 22,574 23,133
Other Loan [Member] | 30 to 59 Days Past Due [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Total Past Due 0 0
Other Loan [Member] | 60 to 89 Days Past Due [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Total Past Due 0 0
Other Loan [Member] | Greater Than 90 Days [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Total Past Due 0 0
Other Loan [Member] | Past Due [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Total Past Due 0 0
Other Loan [Member] | Current [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Total Past Due $ 22,574 $ 23,133