Loans - Summary of financing receivable, past due (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Financing Receivable, Past Due [Line Items]
Nonaccrual	$ 5,141	$ 5,530
Total past due and nonaccrual	9,776	10,866
Gross loans	461,516	415,587
Less: Unearned income	(638)	(719)
Total	460,878	414,868
30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Days past due	3,002	2,398
60-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Days past due	925	885
Greater than 90 Days Past Due & Accruing [Member]
Financing Receivable, Past Due [Line Items]
Days past due	708	2,053
Current Loans [Member]
Financing Receivable, Past Due [Line Items]
Current loans	451,102	404,002
Less: Unearned income	(638)	(719)
Commercial and industrial [Member]
Financing Receivable, Past Due [Line Items]
Nonaccrual	538	312
Total past due and nonaccrual	664	621
Gross loans	50,826	49,076
Commercial and industrial [Member] \| 30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Days past due	126	280
Commercial and industrial [Member] \| 60-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Days past due		29
Commercial and industrial [Member] \| Current Loans [Member]
Financing Receivable, Past Due [Line Items]
Current loans	50,162	48,455
Construction, commercial [Member] \| Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Nonaccrual	942	979
Total past due and nonaccrual	1,446	979
Gross loans	19,876	14,666
Construction, commercial [Member] \| 30-59 Days Past Due [Member] \| Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Days past due	141
Construction, commercial [Member] \| 60-89 Days Past Due [Member] \| Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Days past due	363
Construction, commercial [Member] \| Current Loans [Member] \| Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Current loans	18,430	13,687
Construction, residential [Member] \| Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Total past due and nonaccrual	733	231
Gross loans	16,364	15,102
Construction, residential [Member] \| 30-59 Days Past Due [Member] \| Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Days past due	493
Construction, residential [Member] \| 60-89 Days Past Due [Member] \| Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Days past due	240
Construction, residential [Member] \| Greater than 90 Days Past Due & Accruing [Member] \| Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Days past due		231
Construction, residential [Member] \| Current Loans [Member] \| Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Current loans	15,631	14,871
Mortgage, commercial [Member] \| Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Nonaccrual	2,026	2,441
Total past due and nonaccrual	2,026	3,530
Gross loans	167,223	150,513
Mortgage, commercial [Member] \| 30-59 Days Past Due [Member] \| Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Days past due		218
Mortgage, commercial [Member] \| 60-89 Days Past Due [Member] \| Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Days past due		441
Mortgage, commercial [Member] \| Greater than 90 Days Past Due & Accruing [Member] \| Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Days past due		430
Mortgage, commercial [Member] \| Current Loans [Member] \| Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Current loans	165,197	146,983
Mortgage, residential [Member] \| Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Nonaccrual	947	1,441
Total past due and nonaccrual	3,137	3,287
Gross loans	165,865	149,856
Mortgage, residential [Member] \| 30-59 Days Past Due [Member] \| Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Days past due	1,482	760
Mortgage, residential [Member] \| 60-89 Days Past Due [Member] \| Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Days past due		7
Mortgage, residential [Member] \| Greater than 90 Days Past Due & Accruing [Member] \| Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Days past due	708	1,079
Mortgage, residential [Member] \| Current Loans [Member] \| Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Current loans	162,728	146,569
Agricultural and Farmland [Member]
Financing Receivable, Past Due [Line Items]
Total past due and nonaccrual		432
Gross loans	3,929	4,395
Agricultural and Farmland [Member] \| 30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Days past due		123
Agricultural and Farmland [Member] \| Greater than 90 Days Past Due & Accruing [Member]
Financing Receivable, Past Due [Line Items]
Days past due		309
Agricultural and Farmland [Member] \| Current Loans [Member]
Financing Receivable, Past Due [Line Items]
Current loans	3,929	3,963
Consumer installment loans [Member]
Financing Receivable, Past Due [Line Items]
Nonaccrual	688	357
Total past due and nonaccrual	1,770	1,786
Gross loans	37,433	31,979
Consumer installment loans [Member] \| 30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Days past due	760	1,017
Consumer installment loans [Member] \| 60-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Days past due	322	408
Consumer installment loans [Member] \| Greater than 90 Days Past Due & Accruing [Member]
Financing Receivable, Past Due [Line Items]
Days past due		4
Consumer installment loans [Member] \| Current Loans [Member]
Financing Receivable, Past Due [Line Items]
Current loans	$ 35,663	$ 30,193

Financing receivable total past due and non accrual.

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Amount of financing receivable not past due.

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Amount of financing receivable on nonaccrual status.

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Amount of deferred interest and fee income, unamortized costs incurred to originate loans and leases, unamortized loan commitments and loan syndication fees, and premiums over or discounts from face amounts of acquired loans. Excludes amounts for loans and leases covered under loss sharing agreements.

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