Loans - Analysis of Allowance for Credit Losses (Detail) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
ALLOWANCE FOR CREDIT LOSSES:
Beginning balance	$ 17,283	$ 14,313	$ 14,313
Charge Offs	(94)	(1,013)	(1,332)
Recoveries	43	66	458
Provision (Credit)	580	1,700	3,444
Other Non-interest expense related to unfunded	35	411
Ending Balance	17,847	15,477	17,283
Ending balance: individually evaluated for impairment	1,535	1,109	2,184
Ending balance: collectively evaluated for impairment	16,312	14,368	15,099
Ending balance: loans acquired with deteriorated credit quality	0	0	37
FINANCING RECEIVABLES:
Ending balance	1,962,220	1,341,679	1,857,419
Ending balance: individually evaluated for impairment	12,624	12,136	11,939
Ending balance: collectively evaluated for impairment	1,948,149	1,329,423	1,844,031
Ending balance: loans acquired with deteriorated credit quality	1,447	120	1,449
Consumer Real Estate [Member]
ALLOWANCE FOR CREDIT LOSSES:
Beginning balance	857	633	633
Recoveries	5	3
Provision (Credit)	30	(12)
Ending Balance	892	624	857
Ending balance: individually evaluated for impairment		23
Ending balance: collectively evaluated for impairment	892	601	857
Ending balance: loans acquired with deteriorated credit quality	0	0	37
FINANCING RECEIVABLES:
Ending balance	410,064	175,481	395,805
Ending balance: individually evaluated for impairment	692	951	604
Ending balance: collectively evaluated for impairment	408,694	174,489	394,489
Ending balance: loans acquired with deteriorated credit quality	678	41	712
Agricultural Real Estate [Member]
ALLOWANCE FOR CREDIT LOSSES:
Beginning balance	1,040	958	958
Provision (Credit)	(434)	428
Ending Balance	606	1,386	1,040
Ending balance: individually evaluated for impairment	273	1,086	691
Ending balance: collectively evaluated for impairment	333	300	349
Ending balance: loans acquired with deteriorated credit quality	0	0	0
FINANCING RECEIVABLES:
Ending balance	195,901	179,639	198,033
Ending balance: individually evaluated for impairment	6,670	6,632	6,725
Ending balance: collectively evaluated for impairment	189,033	173,007	191,107
Ending balance: loans acquired with deteriorated credit quality	198		201
Agricultural [Member]
ALLOWANCE FOR CREDIT LOSSES:
Beginning balance	709	701	701
Charge Offs		(142)
Provision (Credit)	135	57
Ending Balance	844	616	709
Ending balance: individually evaluated for impairment			1
Ending balance: collectively evaluated for impairment	844	616	708
Ending balance: loans acquired with deteriorated credit quality	0	0	0
FINANCING RECEIVABLES:
Ending balance	140,847	100,147	118,504
Ending balance: individually evaluated for impairment	20	292	20
Ending balance: collectively evaluated for impairment	140,827	99,855	118,484
Commercial Real Estate [Member]
ALLOWANCE FOR CREDIT LOSSES:
Beginning balance	9,130	7,415	7,415
Recoveries	2	2
Provision (Credit)	441	251
Ending Balance	9,573	7,668	9,130
Ending balance: individually evaluated for impairment	632		664
Ending balance: collectively evaluated for impairment	8,941	7,668	8,466
Ending balance: loans acquired with deteriorated credit quality	0	0	0
FINANCING RECEIVABLES:
Ending balance	909,408	617,512	847,110
Ending balance: individually evaluated for impairment	4,097	2,905	3,561
Ending balance: collectively evaluated for impairment	905,076	614,607	843,299
Ending balance: loans acquired with deteriorated credit quality	235		250
Commercial and Industrial [Member]
ALLOWANCE FOR CREDIT LOSSES:
Beginning balance	3,847	3,346	3,346
Charge Offs	(6)	(809)
Recoveries	9	5
Provision (Credit)	216	66
Ending Balance	4,066	2,608	3,847
Ending balance: individually evaluated for impairment	630		825
Ending balance: collectively evaluated for impairment	3,436	2,608	3,022
Ending balance: loans acquired with deteriorated credit quality	0	0	0
FINANCING RECEIVABLES:
Ending balance	248,362	214,341	240,138
Ending balance: individually evaluated for impairment	1,122	1,335	1,003
Ending balance: collectively evaluated for impairment	246,904	212,927	238,849
Ending balance: loans acquired with deteriorated credit quality	336	79	286
Consumer [Member]
ALLOWANCE FOR CREDIT LOSSES:
Beginning balance	625	606	606
Charge Offs	(88)	(62)
Recoveries	27	56
Provision (Credit)	59	(5)
Ending Balance	623	595	625
Ending balance: individually evaluated for impairment			3
Ending balance: collectively evaluated for impairment	623	595	622
Ending balance: loans acquired with deteriorated credit quality	0	0	0
FINANCING RECEIVABLES:
Ending balance	57,638	54,559	57,829
Ending balance: individually evaluated for impairment	23	21	26
Ending balance: collectively evaluated for impairment	57,615	54,538	57,803
Unallocated [Member]
ALLOWANCE FOR CREDIT LOSSES:
Beginning balance	34	13	13
Provision (Credit)	133	915
Ending Balance	167	928	34
Ending balance: collectively evaluated for impairment	167	928	34
Ending balance: loans acquired with deteriorated credit quality	0	0	0
Unfunded Loan Commitment & Letters of Credit [Member]
ALLOWANCE FOR CREDIT LOSSES:
Beginning balance	1,041	641	641
Other Non-interest expense related to unfunded	35	411
Ending Balance	1,076	1,052	1,041
Ending balance: collectively evaluated for impairment	1,076	1,052	1,041
Ending balance: loans acquired with deteriorated credit quality	$ 0	$ 0	$ 0