Allowances for Loan Losses - Summary of Allowances for Loan Losses by Loan Class (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Loans and Leases Receivable Disclosure [Line Items]
Beginning balance	$ 2,789	$ 2,702
Charge-offs	(339)	(111)
Recoveries	54	14
Provision	648	184
Ending balance	3,152	2,789
Agriculture Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Beginning balance	120	152
Charge-offs	0	0
Recoveries	0	0
Provision	(97)	(32)
Ending balance	23	120
Commercial and PPP Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Beginning balance	290	312
Charge-offs	(24)	0
Recoveries	22	0
Provision	294	(22)
Ending balance	582	290
Commercial Real Estate Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Beginning balance	314	255
Charge-offs	(18)	0
Recoveries	0	0
Provision	503	59
Ending balance	799	314
Residential Real Estate Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Beginning balance	1,702	1,707
Charge-offs	(297)	99
Recoveries	32	7
Provision	197	(87)
Ending balance	1,634	1,702
Consumer Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Beginning balance	35	43
Charge-offs	0	(12)
Recoveries	0	7
Provision	(13)	(3)
Ending balance	22	35
Municipal Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Beginning balance	18	13
Charge-offs	0	0
Recoveries	0	0
Provision	(3)	5
Ending balance	15	18
Unallocated [Member]
Loans and Leases Receivable Disclosure [Line Items]
Beginning balance	310	220
Charge-offs	0	0
Recoveries	0	0
Provision	(233)	90
Ending balance	$ 77	$ 310