Loans - Summary of Activities in Allowance for Credit Losses (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Allowance for Loan Losses
Balance at beginning of year				$ 20,313					$ 20,313
Provision for credit losses-Loans	$ 278	$ 460	$ 143	817	$ 755	$ 1,637	$ 1,628	$ 580	1,698	$ 4,600	$ 3,444
Charge Offs									(990)	(827)
Recoveries									439	298
Balance at ending of year	25,024				20,313				25,024	20,313
Consumer Real Estate [Member]
Allowance for Loan Losses
Balance at beginning of year				998					998
Provision for credit losses-Loans									(326)	121
Charge Offs										0
Recoveries									35	20
Balance at ending of year	3,581				998				3,581	998
Agricultural Real Estate [Member]
Allowance for Loan Losses
Balance at beginning of year				349					349
Provision for credit losses-Loans									24	(691)
Charge Offs										0
Recoveries									105
Balance at ending of year	312				349				312	349
Agricultural [Member]
Allowance for Loan Losses
Balance at beginning of year				751					751
Provision for credit losses-Loans									225	35
Charge Offs										0
Recoveries									10	7
Balance at ending of year	336				751				336	751
Commercial Real Estate [Member]
Allowance for Loan Losses
Balance at beginning of year				11,924					11,924
Provision for credit losses-Loans									1,967	2,785
Recoveries									8	9
Balance at ending of year	17,400				11,924				17,400	11,924
Commercial and Industrial [Member]
Allowance for Loan Losses
Balance at beginning of year				5,382					5,382
Provision for credit losses-Loans									(643)	1,860
Charge Offs									(565)	(418)
Recoveries									84	93
Balance at ending of year	2,093				5,382				2,093	5,382
Consumer [Member]
Allowance for Loan Losses
Balance at beginning of year				909					909
Provision for credit losses-Loans									451	506
Charge Offs									(425)	(409)
Recoveries									197	169
Balance at ending of year	$ 1,302				909				1,302	909
Cumulative Effect, Period of Adoption, Adjustment [Member]
Allowance for Loan Losses
Balance at beginning of year				3,564					$ 3,564
Accounting Standards Update [Extensible Enumeration]									Accounting Standards Update 2016-13 [Member]
Balance at ending of year					3,564					3,564
Cumulative Effect, Period of Adoption, Adjustment [Member] | Consumer Real Estate [Member]
Allowance for Loan Losses
Balance at beginning of year				2,874					$ 2,874
Balance at ending of year					2,874					2,874
Cumulative Effect, Period of Adoption, Adjustment [Member] | Agricultural Real Estate [Member]
Allowance for Loan Losses
Balance at beginning of year				(166)					(166)
Balance at ending of year					(166)					(166)
Cumulative Effect, Period of Adoption, Adjustment [Member] | Agricultural [Member]
Allowance for Loan Losses
Balance at beginning of year				(650)					(650)
Balance at ending of year					(650)					(650)
Cumulative Effect, Period of Adoption, Adjustment [Member] | Commercial Real Estate [Member]
Allowance for Loan Losses
Balance at beginning of year				3,501					3,501
Balance at ending of year					3,501					3,501
Cumulative Effect, Period of Adoption, Adjustment [Member] | Commercial and Industrial [Member]
Allowance for Loan Losses
Balance at beginning of year				(2,165)					(2,165)
Balance at ending of year					(2,165)					(2,165)
Cumulative Effect, Period of Adoption, Adjustment [Member] | Consumer [Member]
Allowance for Loan Losses
Balance at beginning of year				$ 170					$ 170
Balance at ending of year					$ 170					$ 170