Allowance for Loan Losses - Ending Allocation of Allowance for Loan Losses and Loan Balances Outstanding (Detail) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2021	Dec. 31, 2020
Accounts Notes And Loans Receivable [Line Items]
Allowance for loan losses, Individually evaluated for impairment	$ 18	$ 18
Allowance for loan losses, Collectively evaluated for impairment	27,015	26,623
Allowance for loan losses, Total	27,033	26,641	$ 26,133	$ 25,028
Outstanding loan balances, Individually evaluated for impairment	1,202	1,222
Outstanding loan balances, Collectively evaluated for impairment	2,016,696	1,996,367
Outstanding loan balances, Total	2,018,188	1,997,879
Receivables Acquired with Deteriorated Credit Quality [Member]
Accounts Notes And Loans Receivable [Line Items]
Loan balance of loans acquired with credit deterioration	290	290
Commercial and Agriculture [Member]
Accounts Notes And Loans Receivable [Line Items]
Allowance for loan losses, Collectively evaluated for impairment	2,584	2,600
Allowance for loan losses, Total	2,584	2,600	2,360	2,810
Outstanding loan balances, Collectively evaluated for impairment	218,443	246,502
Outstanding loan balances, Total	218,443	246,502
Commercial Real Estate Owner Occupied [Member]
Accounts Notes And Loans Receivable [Line Items]
Allowance for loan losses, Individually evaluated for impairment	6	7
Allowance for loan losses, Collectively evaluated for impairment	4,588	4,457
Allowance for loan losses, Total	4,594	4,464	4,049	4,057
Outstanding loan balances, Individually evaluated for impairment	181	187
Outstanding loan balances, Collectively evaluated for impairment	301,171	295,265
Outstanding loan balances, Total	301,352	295,452
Commercial Real Estate Non Owner Occupied [Member]
Accounts Notes And Loans Receivable [Line Items]
Allowance for loan losses, Collectively evaluated for impairment	14,577	13,860
Allowance for loan losses, Total	14,577	13,860	13,209	12,451
Outstanding loan balances, Individually evaluated for impairment		0
Outstanding loan balances, Collectively evaluated for impairment	869,663	829,310
Outstanding loan balances, Total	869,663	829,310
Residential Real Estate [Member]
Accounts Notes And Loans Receivable [Line Items]
Allowance for loan losses, Individually evaluated for impairment	12	11
Allowance for loan losses, Collectively evaluated for impairment	2,600	2,586
Allowance for loan losses, Total	2,612	2,597	2,509	2,484
Outstanding loan balances, Individually evaluated for impairment	514	526
Outstanding loan balances, Collectively evaluated for impairment	431,966	429,244
Outstanding loan balances, Total	432,770	430,060
Residential Real Estate [Member] \| Receivables Acquired with Deteriorated Credit Quality [Member]
Accounts Notes And Loans Receivable [Line Items]
Loan balance of loans acquired with credit deterioration	290	290
Real Estate Construction [Member]
Accounts Notes And Loans Receivable [Line Items]
Allowance for loan losses, Collectively evaluated for impairment	1,863	1,810
Allowance for loan losses, Total	1,863	1,810	2,902	2,439
Outstanding loan balances, Collectively evaluated for impairment	161,651	157,127
Outstanding loan balances, Total	161,651	157,127
Farm Real Estate [Member]
Accounts Notes And Loans Receivable [Line Items]
Allowance for loan losses, Collectively evaluated for impairment	249	287
Allowance for loan losses, Total	249	287	283	338
Outstanding loan balances, Individually evaluated for impairment	507	509
Outstanding loan balances, Collectively evaluated for impairment	24,141	27,910
Outstanding loan balances, Total	24,648	28,419
Consumer and Other [Member]
Accounts Notes And Loans Receivable [Line Items]
Allowance for loan losses, Collectively evaluated for impairment	136	176
Allowance for loan losses, Total	136	176	170	209
Outstanding loan balances, Collectively evaluated for impairment	9,661	11,009
Outstanding loan balances, Total	9,661	11,009
Unallocated [Member]
Accounts Notes And Loans Receivable [Line Items]
Allowance for loan losses, Collectively evaluated for impairment	418	847
Allowance for loan losses, Total	$ 418	$ 847	$ 651	$ 240

Financing receivable acquired with credit deterioration.

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Amount of allowance for credit loss on accounts receivable.

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Amount of valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment.

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Amount before allowance of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

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