v3.26.3
Loans - Schedule of Nonaccrual Loans by Portfolio Segment (Detail) - USD ($)
$ in Thousands
Sep. 30, 2026
Dec. 31, 2025
Nonaccrual With No Allowance For Credit Loss [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Investment in nonaccrual loans $ 2,958 $ 10,411
Nonaccrual With No Allowance For Credit Loss [Member] | Consumer Real Estate [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Investment in nonaccrual loans 2,102 3,339
Nonaccrual With No Allowance For Credit Loss [Member] | Agricultural Real Estate [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Investment in nonaccrual loans 722 5,347
Nonaccrual With No Allowance For Credit Loss [Member] | Agricultural [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Investment in nonaccrual loans 110 1,441
Nonaccrual With No Allowance For Credit Loss [Member] | Commercial Real Estate [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Investment in nonaccrual loans 0 141
Nonaccrual With No Allowance For Credit Loss [Member] | Commercial & Industrial [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Investment in nonaccrual loans 0 0
Nonaccrual With No Allowance For Credit Loss [Member] | Consumer [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Investment in nonaccrual loans 24 143
Nonaccrual With No Allowance For Credit Loss [Member] | Other [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Investment in nonaccrual loans 0  
Nonaccrual [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Investment in nonaccrual loans 6,219 11,256
Nonaccrual [Member] | Consumer Real Estate [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Investment in nonaccrual loans 2,372 4,050
Nonaccrual [Member] | Agricultural Real Estate [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Investment in nonaccrual loans 3,713 5,347
Nonaccrual [Member] | Agricultural [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Investment in nonaccrual loans 110 1,441
Nonaccrual [Member] | Commercial Real Estate [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Investment in nonaccrual loans 0 141
Nonaccrual [Member] | Commercial & Industrial [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Investment in nonaccrual loans 0 134
Nonaccrual [Member] | Consumer [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Investment in nonaccrual loans 24 $ 143
Nonaccrual [Member] | Other [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Investment in nonaccrual loans $ 0