Loans - Recorded Investment in Nonaccrual Loans by Portfolio Class of Loans (Detail) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Accounts, Notes, Loans and Financing Receivable [Line Items]
Investment in nonaccrual loans	$ 4,689	$ 8,076
Consumer Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Investment in nonaccrual loans	612	824
Agricultural Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Investment in nonaccrual loans	1,921	6,477
Agricultural [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Investment in nonaccrual loans	152	20
Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Investment in nonaccrual loans	903	600
Commercial and Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Investment in nonaccrual loans	1,096	149
Consumer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Investment in nonaccrual loans	$ 5	$ 6