Loans - Summary of Activities in Allowance for Credit Losses (Detail) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended	12 Months Ended
Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025	Dec. 31, 2025
Allowance for Loan Losses
Balance at beginning of year	$ 27,830	$ 26,352	$ 27,688	$ 25,826	$ 25,826
Provision for (recovery of) credit losses - loans	173	661	475	1,472	2,596
Charge Offs	(173)	(132)	(407)	(467)	(1,028)
Recoveries	111	96	185	146	294
Balance at ending of year	27,941	26,977	27,941	26,977	27,688
Consumer Real Estate [Member]
Allowance for Loan Losses
Balance at beginning of year	4,599	3,683	4,266	3,543	3,543
Provision for (recovery of) credit losses - loans	452	(31)	786	108	738
Charge Offs			(3)		(20)
Recoveries	2	1	4	2	5
Balance at ending of year	5,053	3,653	5,053	3,653	4,266
Agricultural Real Estate [Member]
Allowance for Loan Losses
Balance at beginning of year	1,092	771	735	895	895
Provision for (recovery of) credit losses - loans	(146)	(33)	211	(157)	(160)
Balance at ending of year	946	738	946	738	735
Agricultural [Member]
Allowance for Loan Losses
Balance at beginning of year	516	306	474	285	285
Provision for (recovery of) credit losses - loans	298	27	340	39	179
Recoveries	52	1	52	10	10
Balance at ending of year	866	334	866	334	474
Commercial Real Estate [Member]
Allowance for Loan Losses
Balance at beginning of year	16,282	16,907	17,428	16,560	16,560
Provision for (recovery of) credit losses - loans	(390)	431	(1,539)	775	844
Recoveries	2	16	5	19	24
Balance at ending of year	15,894	17,354	15,894	17,354	17,428
Commercial and Industrial [Member]
Allowance for Loan Losses
Balance at beginning of year	3,486	3,165	3,286	2,969	2,969
Provision for (recovery of) credit losses - loans	52	205	250	420	533
Charge Offs	(39)	0	(39)	(25)	(250)
Recoveries	1	6	3	12	34
Balance at ending of year	3,500	3,376	3,500	3,376	3,286
Consumer [Member]
Allowance for Loan Losses
Balance at beginning of year	1,316	952	953	1,012	1,012
Provision for (recovery of) credit losses - loans	(89)	53	438	272	478
Charge Offs	(134)	(132)	(365)	(442)	(758)
Recoveries	54	72	121	103	221
Balance at ending of year	1,147	945	1,147	945	953
Other [Member]
Allowance for Loan Losses
Balance at beginning of year	539	568	546	562	562
Provision for (recovery of) credit losses - loans	(4)	9	(11)	15	(16)
Balance at ending of year	$ 535	$ 577	$ 535	$ 577	$ 546

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Amount of allowance for credit loss on financing receivable. Excludes allowance for financing receivable covered under loss sharing agreement.

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Amount of increase in allowance for credit loss on financing receivable from recovery.

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