Loans - Summary of Activities in Allowance for Credit Losses (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Allowance for Loan Losses
Balance at beginning of year	$ 24,910		$ 20,313
Provision for credit losses-Loans	460	$ 1,637	1,420	$ 3,845	$ 4,600
Charge Offs	(148)	(123)	(330)	(334)	(827)
Recoveries	55	52	310	237	298
Balance at ending of year	25,277		25,277		20,313
Consumer Real Estate [Member]
Allowance for Loan Losses
Balance at beginning of year	3,998		998
Provision for credit losses-Loans	(170)	19	(57)	54	121
Recoveries	14	6	27	15	20
Balance at ending of year	3,842		3,842		998
Agricultural Real Estate [Member]
Allowance for Loan Losses
Balance at beginning of year	237		349
Provision for credit losses-Loans	77	(10)	27	(684)	(691)
Recoveries	1		105
Balance at ending of year	315		315		349
Agricultural [Member]
Allowance for Loan Losses
Balance at beginning of year	107		751
Provision for credit losses-Loans	78	(1)	84	46	35
Recoveries		1		1	7
Balance at ending of year	185		185		751
Commercial Real Estate [Member]
Allowance for Loan Losses
Balance at beginning of year	16,681		11,924
Provision for credit losses-Loans	123	(1,122)	1,374	2,414	2,785
Recoveries	1	2	6	7	9
Balance at ending of year	16,805		16,805		11,924
Commercial and Industrial [Member]
Allowance for Loan Losses
Balance at beginning of year	2,767		5,382
Provision for credit losses-Loans	(65)	297	(527)	1,747	1,860
Charge Offs				(6)	(418)
Recoveries	6	8	18	82	93
Balance at ending of year	2,708		2,708		5,382
Consumer [Member]
Allowance for Loan Losses
Balance at beginning of year	1,120		909
Provision for credit losses-Loans	417	246	519	296	506
Charge Offs	(148)	(123)	(330)	(328)	(409)
Recoveries	33	$ 35	154	$ 132	169
Balance at ending of year	$ 1,422		1,422		909
Cumulative Effect, Period of Adoption, Adjustment [Member]
Allowance for Loan Losses
Balance at beginning of year			$ 3,564
Accounting Standards Update [Extensible Enumeration]			Accounting Standards Update 2016-13 [Member]
Balance at ending of year					3,564
Cumulative Effect, Period of Adoption, Adjustment [Member] | Consumer Real Estate [Member]
Allowance for Loan Losses
Balance at beginning of year			$ 2,874
Balance at ending of year					2,874
Cumulative Effect, Period of Adoption, Adjustment [Member] | Agricultural Real Estate [Member]
Allowance for Loan Losses
Balance at beginning of year			(166)
Balance at ending of year					(166)
Cumulative Effect, Period of Adoption, Adjustment [Member] | Agricultural [Member]
Allowance for Loan Losses
Balance at beginning of year			(650)
Balance at ending of year					(650)
Cumulative Effect, Period of Adoption, Adjustment [Member] | Commercial Real Estate [Member]
Allowance for Loan Losses
Balance at beginning of year			3,501
Balance at ending of year					3,501
Cumulative Effect, Period of Adoption, Adjustment [Member] | Commercial and Industrial [Member]
Allowance for Loan Losses
Balance at beginning of year			(2,165)
Balance at ending of year					(2,165)
Cumulative Effect, Period of Adoption, Adjustment [Member] | Consumer [Member]
Allowance for Loan Losses
Balance at beginning of year			$ 170
Balance at ending of year					$ 170