Allowance for Credit Losses - Summary of Allowances for Loan Losses by Loan Class (Detail) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Loans and Leases Receivable Disclosure [Line Items]
Beginning balance	$ 3,443	$ 4,666	$ 3,152
Charge-offs	(2)		(2)
Recoveries	54		65
Provision for credit losses	395	(200)	675
Ending balance	3,890	10,228	3,890
Agriculture Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Beginning balance	20	33	23
Charge-offs	0		0
Recoveries	0		0
Provision for credit losses	(3)		(6)
Ending balance	17		17
Commercial and PPP Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Beginning balance	585	583	582
Charge-offs	(1)		(1)
Recoveries	5		7
Provision for credit losses	(83)		(82)
Ending balance	506		506
Commercial Real Estate Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Beginning balance	1,070	2,462	799
Charge-offs	(1)		(1)
Recoveries	0		0
Provision for credit losses	717		988
Ending balance	1,786		1,786
Residential Real Estate Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Beginning balance	1,728	1,536	1,634
Charge-offs	0		0
Recoveries	49		56
Provision for credit losses	(230)		(143)
Ending balance	1,547		1,547
Consumer Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Beginning balance	13	40	22
Charge-offs	0		0
Recoveries	0		2
Provision for credit losses	8		(3)
Ending balance	21		21
Municipal Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Beginning balance	15	12	15
Charge-offs	0		0
Recoveries	0		0
Provision for credit losses	(2)		(2)
Ending balance	13		13
Unallocated [Member]
Loans and Leases Receivable Disclosure [Line Items]
Beginning balance	12	$ 0	77
Charge-offs	0		0
Recoveries	0		0
Provision for credit losses	(12)		(77)
Ending balance	$ 0		$ 0