Allowances for Loan Losses - Summary of Classes of the Loan Portfolio Summarized by the Internal Risk Rating System (Detail) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Gross	$ 731,080	$ 715,039
Agriculture Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Gross	8,111	9,341
Commercial and PPP Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Gross	104,700	122,378
Commercial Real Estate Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Gross	353,559	338,749
Residential Real Estate Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Gross	252,158	231,302
Consumer Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Gross	6,359	7,087
Municipal Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Gross	6,193	6,182
Pass [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Gross	718,372	701,348
Pass [Member] | Agriculture Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Gross	7,861	9,341
Pass [Member] | Commercial and PPP Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Gross	98,520	117,918
Pass [Member] | Commercial Real Estate Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Gross	350,995	332,156
Pass [Member] | Residential Real Estate Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Gross	248,444	228,664
Pass [Member] | Consumer Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Gross	6,359	7,087
Pass [Member] | Municipal Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Gross	6,193	6,182
Special Mention [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Gross	9,017	7,491
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	5,504	3,757
Special Mention [Member] | Commercial Real Estate Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Gross	1,965	2,077
Special Mention [Member] | Residential Real Estate Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Gross	1,548	1,657
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	3,691	6,200
Substandard [Member] | Agriculture Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Gross	250
Substandard [Member] | Commercial and PPP Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Gross	676	703
Substandard [Member] | Commercial Real Estate Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Gross	599	4,516
Substandard [Member] | Residential Real Estate Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Gross	2,166	981
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