Loans - Loans (Detail) - USD ($) $ in Thousands	Mar. 31, 2025	Dec. 31, 2024	Mar. 31, 2024	Dec. 31, 2023
Loans:
Loans - Gross	$ 2,581,940	$ 2,562,545
Less: Net deferred loan fees and costs	(1,748)	(1,750)
Loans after net deferred loan fees and costs	2,580,192	2,560,795
Less: Allowance for credit losses	(26,352)	(25,826)	$ (24,680)	$ (25,024)
Plus: Basis adjustment related to fair value hedges	1,712	1,074
Loans - Net	2,555,552	2,536,043
Consumer Real Estate [Member]
Loans:
Loans - Gross	523,383	520,114
Less: Allowance for credit losses	(3,683)	(3,543)	(3,285)	(3,581)
Agricultural Real Estate [Member]
Loans:
Loans - Gross	215,898	216,401
Less: Allowance for credit losses	(771)	(895)	(1,171)	(312)
Agricultural [Member]
Loans:
Loans - Gross	153,607	152,080
Less: Allowance for credit losses	(306)	(285)	(377)	(336)
Commercial Real Estate [Member]
Loans:
Loans - Gross	1,325,698	1,310,811
Less: Allowance for credit losses	(16,907)	(16,560)	(15,953)	(17,400)
Commercial and Industrial [Member]
Loans:
Loans - Gross	278,254	275,152
Consumer [Member]
Loans:
Loans - Gross	60,115	63,009
Less: Allowance for credit losses	(952)	(1,012)	$ (1,162)	$ (1,302)
Other Loan [Member]
Loans:
Loans - Gross	$ 24,985	$ 24,978