Allowance for Credit Losses - Summary of Classes of the Loan Portfolio Summarized by the Internal Risk Rating System (Detail) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Gross	$ 978,475	$ 927,615
Agriculture Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Gross		15,591
Commercial and PPP Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Gross		104,755
Commercial Real Estate Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Gross		540,914
Residential Real Estate Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Gross		250,832
Consumer Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Gross	4,137	10,057
Municipal Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Gross	$ 11,869	5,466
Pass [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Gross		912,686
Pass [Member] | Agriculture Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Gross		15,291
Pass [Member] | Commercial and PPP Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Gross		101,980
Pass [Member] | Commercial Real Estate Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Gross		533,864
Pass [Member] | Residential Real Estate Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Gross		246,028
Pass [Member] | Consumer Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Gross		10,057
Pass [Member] | Municipal Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Gross		5,466
Special Mention [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Gross		5,444
Special Mention [Member] | Agriculture Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Gross		0
Special Mention [Member] | Commercial and PPP Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Gross		2,721
Special Mention [Member] | Commercial Real Estate Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Gross		2,516
Special Mention [Member] | Residential Real Estate Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Gross		207
Special Mention [Member] | Consumer Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Gross		0
Special Mention [Member] | Municipal Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Gross		0
Substandard [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Gross		9,485
Substandard [Member] | Agriculture Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Gross		300
Substandard [Member] | Commercial and PPP Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Gross		54
Substandard [Member] | Commercial Real Estate Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Gross		4,534
Substandard [Member] | Residential Real Estate Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Gross		4,597
Substandard [Member] | Consumer Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Gross		0
Substandard [Member] | Municipal Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Gross		0
Doubtful [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Gross		0
Doubtful [Member] | Agriculture Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Gross		0
Doubtful [Member] | Commercial and PPP Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Gross		0
Doubtful [Member] | Commercial Real Estate Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Gross		0
Doubtful [Member] | Residential Real Estate Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Gross		0
Doubtful [Member] | Consumer Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Gross		0
Doubtful [Member] | Municipal Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Gross		$ 0