Loans - Distribution of Fixed Rate Loans and Variable Rate Loans by Major Loan Category (Detail) $ in Thousands	Sep. 30, 2022 USD ($)
Consumer Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Distribution of fixed rate loans by major loan category, Fixed Rate	$ 293,912
Distribution of variable rate loans by major loan category, Variable Rate	122,089
Agricultural Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Distribution of fixed rate loans by major loan category, Fixed Rate	130,078
Distribution of variable rate loans by major loan category, Variable Rate	75,011
Agricultural [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Distribution of fixed rate loans by major loan category, Fixed Rate	50,658
Distribution of variable rate loans by major loan category, Variable Rate	77,957
Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Distribution of fixed rate loans by major loan category, Fixed Rate	871,664
Distribution of variable rate loans by major loan category, Variable Rate	191,997
Commercial and Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Distribution of fixed rate loans by major loan category, Fixed Rate	113,171
Distribution of variable rate loans by major loan category, Variable Rate	116,217
Consumer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Distribution of fixed rate loans by major loan category, Fixed Rate	67,154
Distribution of variable rate loans by major loan category, Variable Rate	3,448
Other Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Distribution of fixed rate loans by major loan category, Fixed Rate	20,862
Distribution of variable rate loans by major loan category, Variable Rate	$ 9,800