Loans - Analysis of Allowance for Credit Losses (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022
ALLOWANCE FOR CREDIT LOSSES:
Balance at beginning of year		$ 17,847	$ 21,575	$ 17,283	$ 17,283
Charge Offs	$ (60)	(117)	(182)	(211)	(827)
Recoveries	193	142	255	185	298
Provision for credit losses-loans	143	1,628	960	2,208	4,600
Provision for credit losses-off balance sheet credit exposures	(129)		(67)
Other Non-interest expense related to unfunded		91		126	221
Balance at ending of year		19,591		19,591	21,575
Ending balance: individually evaluated for impairment		2,419		2,419	1,996
Ending balance: collectively evaluated for impairment		17,172		17,172	19,579
Ending balance: loans acquired with deteriorated credit quality					0
FINANCING RECEIVABLES:
Ending balance	2,515,793	2,034,818	$ 2,515,793	2,034,818	2,356,387
Ending balance: individually evaluated for impairment		10,669		10,669	8,857
Ending balance: collectively evaluated for impairment		2,023,141		2,023,141	2,346,871
Ending balance: loans acquired with deteriorated credit quality		1,008		1,008	659
Cumulative Effect, Period of Adoption, Adjustment [Member]
ALLOWANCE FOR CREDIT LOSSES:
Accounting Standards Update [Extensible Enumeration]			Accounting Standards Update 2016-13 [Member]
Consumer Real Estate [Member]
ALLOWANCE FOR CREDIT LOSSES:
Balance at beginning of year		892	$ 998	857	857
Recoveries	6	4	13	9	20
Provision for credit losses-loans	369	43	113	73	121
Balance at ending of year		939		939	998
Ending balance: individually evaluated for impairment					6
Ending balance: collectively evaluated for impairment		939		939	992
Ending balance: loans acquired with deteriorated credit quality		0		0	0
FINANCING RECEIVABLES:
Ending balance	506,842	410,468	506,842	410,468	494,423
Ending balance: individually evaluated for impairment		657		657	569
Ending balance: collectively evaluated for impairment		409,318		409,318	493,449
Ending balance: loans acquired with deteriorated credit quality		493		493	405
Agricultural Real Estate [Member]
ALLOWANCE FOR CREDIT LOSSES:
Balance at beginning of year		606	349	1,040	1,040
Recoveries	104		104
Provision for credit losses-loans	(76)	(260)	(50)	(694)	(691)
Balance at ending of year		346		346	349
Ending balance: individually evaluated for impairment					0
Ending balance: collectively evaluated for impairment		346		346	349
Ending balance: loans acquired with deteriorated credit quality		0		0	0
FINANCING RECEIVABLES:
Ending balance	230,531	199,650	230,531	199,650	220,514
Ending balance: individually evaluated for impairment		2,414		2,414	2,280
Ending balance: collectively evaluated for impairment		197,039		197,039	218,039
Ending balance: loans acquired with deteriorated credit quality		197		197	195
Agricultural [Member]
ALLOWANCE FOR CREDIT LOSSES:
Balance at beginning of year		844	751	709	709
Recoveries					7
Provision for credit losses-loans	41	(90)	6	45	35
Balance at ending of year		754		754	751
Ending balance: individually evaluated for impairment					0
Ending balance: collectively evaluated for impairment		754		754	751
Ending balance: loans acquired with deteriorated credit quality		0		0	0
FINANCING RECEIVABLES:
Ending balance	128,593	127,340	128,593	127,340	128,926
Ending balance: individually evaluated for impairment		1,296		1,296	152
Ending balance: collectively evaluated for impairment		126,044		126,044	128,774
Commercial Real Estate [Member]
ALLOWANCE FOR CREDIT LOSSES:
Balance at beginning of year		9,573	11,924	9,130	9,130
Recoveries	3	3	5	5	9
Provision for credit losses-loans	590	851	1,251	1,292	2,785
Balance at ending of year		10,427		10,427	11,924
Ending balance: individually evaluated for impairment					438
Ending balance: collectively evaluated for impairment		10,427		10,427	11,486
Ending balance: loans acquired with deteriorated credit quality		0		0	0
FINANCING RECEIVABLES:
Ending balance	1,278,445	977,588	1,278,445	977,588	1,150,511
Ending balance: individually evaluated for impairment		4,133		4,133	4,108
Ending balance: collectively evaluated for impairment		973,258		973,258	1,146,389
Ending balance: loans acquired with deteriorated credit quality		197		197	14
Commercial and Industrial [Member]
ALLOWANCE FOR CREDIT LOSSES:
Balance at beginning of year		4,066	5,382	3,847	3,847
Charge Offs				(6)	(418)
Recoveries	6	65	12	74	93
Provision for credit losses-loans	(653)	1,234	(462)	1,450	1,860
Balance at ending of year		5,365		5,365	5,382
Ending balance: individually evaluated for impairment		2,419		2,419	1,551
Ending balance: collectively evaluated for impairment		2,946		2,946	3,831
Ending balance: loans acquired with deteriorated credit quality		0		0	0
FINANCING RECEIVABLES:
Ending balance	282,244	264,124	282,244	264,124	272,119
Ending balance: individually evaluated for impairment		2,149		2,149	1,581
Ending balance: collectively evaluated for impairment		261,854		261,854	270,493
Ending balance: loans acquired with deteriorated credit quality		121		121	45
Consumer [Member]
ALLOWANCE FOR CREDIT LOSSES:
Balance at beginning of year		623	891	625	625
Charge Offs	(60)	(117)	(182)	(205)	(409)
Recoveries	74	70	121	97	169
Provision for credit losses-loans	(128)	(9)	102	50	506
Balance at ending of year		567		567	891
Ending balance: individually evaluated for impairment					1
Ending balance: collectively evaluated for impairment		567		567	890
Ending balance: loans acquired with deteriorated credit quality		0		0	0
FINANCING RECEIVABLES:
Ending balance	89,138	55,648	89,138	55,648	89,894
Ending balance: individually evaluated for impairment		20		20	167
Ending balance: collectively evaluated for impairment		55,628		55,628	89,727
Unallocated [Member]
ALLOWANCE FOR CREDIT LOSSES:
Balance at beginning of year		167	18	34	34
Provision for credit losses-loans		(141)		(8)	(16)
Balance at ending of year		26		26	18
Ending balance: collectively evaluated for impairment		26		26	18
Ending balance: loans acquired with deteriorated credit quality		0		0	0
Unfunded Loan Commitment & Letters of Credit [Member]
ALLOWANCE FOR CREDIT LOSSES:
Balance at beginning of year	2,228	1,076	1,262	1,041	1,041
Provision for credit losses-off balance sheet credit exposures	(129)		(67)
Other Non-interest expense related to unfunded		91		126	221
Balance at ending of year	$ 2,099	1,167	2,099	1,167	1,262
Ending balance: collectively evaluated for impairment		1,167		1,167	1,262
Ending balance: loans acquired with deteriorated credit quality		$ 0		$ 0	0
Unfunded Loan Commitment & Letters of Credit [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member]
ALLOWANCE FOR CREDIT LOSSES:
Balance at beginning of year			$ 904
Balance at ending of year					$ 904