Loans - Analysis of Allowance for Credit Losses (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
ALLOWANCE FOR CREDIT LOSSES:
Beginning balance	$ 19,591	$ 16,232	$ 17,283	$ 14,313	$ 14,313
Charge Offs	(123)	(103)	(334)	(1,154)	(1,332)
Recoveries	52	55	237	180	458
Provision (Credit)	1,637	659	3,845	3,000	3,444
Other Non-interest expense related to unfunded	(49)	(106)	77	398
Ending Balance	21,108	16,737	21,108	16,737	17,283
Ending balance: individually evaluated for impairment	2,436	2,400	2,436	2,400	2,184
Ending balance: collectively evaluated for impairment	18,672	14,337	18,672	14,337	15,099
Ending balance: loans acquired with deteriorated credit quality	0	0	0	0	37
FINANCING RECEIVABLES:
Ending balance	2,142,616	1,495,562	2,142,616	1,495,562	1,857,419
Ending balance: individually evaluated for impairment	10,753	11,849	10,753	11,849	11,939
Ending balance: collectively evaluated for impairment	2,131,131	1,483,054	2,131,131	1,483,054	1,844,031
Ending balance: loans acquired with deteriorated credit quality	732	659	732	659	1,449
Consumer Real Estate [Member]
ALLOWANCE FOR CREDIT LOSSES:
Beginning balance	939	649	857	633	633
Charge Offs		(2)		(2)
Recoveries	6	3	15	9
Provision (Credit)	(19)	146	54	156
Ending Balance	926	796	926	796	857
Ending balance: collectively evaluated for impairment	926	796	926	796	857
Ending balance: loans acquired with deteriorated credit quality	0	0	0	0	37
FINANCING RECEIVABLES:
Ending balance	416,044	202,370	416,044	202,370	395,805
Ending balance: individually evaluated for impairment	624	714	624	714	604
Ending balance: collectively evaluated for impairment	414,951	201,595	414,951	201,595	394,489
Ending balance: loans acquired with deteriorated credit quality	469	61	469	61	712
Agricultural Real Estate [Member]
ALLOWANCE FOR CREDIT LOSSES:
Beginning balance	346	1,217	1,040	958	958
Provision (Credit)	10	(291)	(684)	(32)
Ending Balance	356	926	356	926	1,040
Ending balance: individually evaluated for impairment		636		636	691
Ending balance: collectively evaluated for impairment	356	290	356	290	349
Ending balance: loans acquired with deteriorated credit quality	0	0	0	0	0
FINANCING RECEIVABLES:
Ending balance	204,787	179,051	204,787	179,051	198,033
Ending balance: individually evaluated for impairment	2,588	6,051	2,588	6,051	6,725
Ending balance: collectively evaluated for impairment	202,003	173,000	202,003	173,000	191,107
Ending balance: loans acquired with deteriorated credit quality	196		196		201
Agricultural [Member]
ALLOWANCE FOR CREDIT LOSSES:
Beginning balance	754	720	709	701	701
Charge Offs		(1)		(143)
Recoveries	1	1	1	7
Provision (Credit)	1	(33)	46	122
Ending Balance	756	687	756	687	709
Ending balance: individually evaluated for impairment		54		54	1
Ending balance: collectively evaluated for impairment	756	633	756	633	708
Ending balance: loans acquired with deteriorated credit quality	0	0	0	0	0
FINANCING RECEIVABLES:
Ending balance	128,818	105,722	128,818	105,722	118,504
Ending balance: individually evaluated for impairment	1,334	247	1,334	247	20
Ending balance: collectively evaluated for impairment	127,484	105,475	127,484	105,475	118,484
Commercial Real Estate [Member]
ALLOWANCE FOR CREDIT LOSSES:
Beginning balance	10,427	8,831	9,130	7,415	7,415
Recoveries	2	3	7	8
Provision (Credit)	1,122	(469)	2,414	942
Ending Balance	11,551	8,365	11,551	8,365	9,130
Ending balance: individually evaluated for impairment	500	710	500	710	664
Ending balance: collectively evaluated for impairment	11,051	7,655	11,051	7,655	8,466
Ending balance: loans acquired with deteriorated credit quality	0	0	0	0	0
FINANCING RECEIVABLES:
Ending balance	1,061,904	727,418	1,061,904	727,418	847,110
Ending balance: individually evaluated for impairment	4,187	3,607	4,187	3,607	3,561
Ending balance: collectively evaluated for impairment	1,057,699	723,577	1,057,699	723,577	843,299
Ending balance: loans acquired with deteriorated credit quality	18	234	18	234	250
Commercial and Industrial [Member]
ALLOWANCE FOR CREDIT LOSSES:
Beginning balance	5,365	2,837	3,847	3,346	3,346
Charge Offs		(5)	(6)	(814)
Recoveries	8	9	82	19
Provision (Credit)	297	973	1,747	1,263
Ending Balance	5,670	3,814	5,670	3,814	3,847
Ending balance: individually evaluated for impairment	1,936	1,000	1,936	1,000	825
Ending balance: collectively evaluated for impairment	3,734	2,814	3,734	2,814	3,022
Ending balance: loans acquired with deteriorated credit quality	0	0	0	0	0
FINANCING RECEIVABLES:
Ending balance	260,000	225,382	260,000	225,382	240,138
Ending balance: individually evaluated for impairment	2,003	1,215	2,003	1,215	1,003
Ending balance: collectively evaluated for impairment	257,948	223,803	257,948	223,803	238,849
Ending balance: loans acquired with deteriorated credit quality	49	364	49	364	286
Consumer [Member]
ALLOWANCE FOR CREDIT LOSSES:
Beginning balance	567	613	625	606	606
Charge Offs	(123)	(95)	(328)	(195)
Recoveries	35	39	132	137
Provision (Credit)	246	49	296	58
Ending Balance	725	606	725	606	625
Ending balance: individually evaluated for impairment					3
Ending balance: collectively evaluated for impairment	725	606	725	606	622
Ending balance: loans acquired with deteriorated credit quality	0	0	0	0	0
FINANCING RECEIVABLES:
Ending balance	71,063	55,619	71,063	55,619	57,829
Ending balance: individually evaluated for impairment	17	15	17	15	26
Ending balance: collectively evaluated for impairment	71,046	55,604	71,046	55,604	57,803
Unallocated [Member]
ALLOWANCE FOR CREDIT LOSSES:
Beginning balance	26	220	34	13	13
Provision (Credit)	(20)	284	(28)	491
Ending Balance	6	504	6	504	34
Ending balance: collectively evaluated for impairment	6	504	6	504	34
Ending balance: loans acquired with deteriorated credit quality	0	0	0	0	0
Unfunded Loan Commitment & Letters of Credit [Member]
ALLOWANCE FOR CREDIT LOSSES:
Beginning balance	1,167	1,145	1,041	641	641
Other Non-interest expense related to unfunded	(49)	(106)	77	398
Ending Balance	1,118	1,039	1,118	1,039	1,041
Ending balance: collectively evaluated for impairment	1,118	1,039	1,118	1,039	1,041
Ending balance: loans acquired with deteriorated credit quality	$ 0	$ 0	$ 0	$ 0	$ 0