Loans - Distribution of Fixed Rate Loans and Variable Rate Loans by Major Loan Category (Detail) $ in Thousands	Dec. 31, 2023 USD ($)
Consumer Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Distribution of fixed rate loans by major loan category, Fixed Rate	$ 329,142
Distribution of variable rate loans by major loan category, Variable Rate	192,753
Agricultural Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Distribution of fixed rate loans by major loan category, Fixed Rate	123,783
Distribution of variable rate loans by major loan category, Variable Rate	100,008
Agricultural [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Distribution of fixed rate loans by major loan category, Fixed Rate	56,269
Distribution of variable rate loans by major loan category, Variable Rate	76,291
Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Distribution of fixed rate loans by major loan category, Fixed Rate	1,024,989
Distribution of variable rate loans by major loan category, Variable Rate	312,777
Commercial and Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Distribution of fixed rate loans by major loan category, Fixed Rate	131,385
Distribution of variable rate loans by major loan category, Variable Rate	123,550
Consumer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Distribution of fixed rate loans by major loan category, Fixed Rate	79,526
Distribution of variable rate loans by major loan category, Variable Rate	65
Other Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Distribution of fixed rate loans by major loan category, Fixed Rate	20,552
Distribution of variable rate loans by major loan category, Variable Rate	$ 9,584