Loans - Summary of loans held for investment (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Loans and Leases Receivable Disclosure [Line Items]
Gross loans	$ 461,516	$ 415,587
Less: Unearned income	(638)	(719)
Total	460,878	414,868
Commercial and industrial [Member]
Loans and Leases Receivable Disclosure [Line Items]
Gross loans	50,826	49,076
Agricultural [Member]
Loans and Leases Receivable Disclosure [Line Items]
Gross loans	175	216
Construction, commercial [Member] \| Real Estate [Member]
Loans and Leases Receivable Disclosure [Line Items]
Gross loans	19,876	14,666
Construction, residential [Member] \| Real Estate [Member]
Loans and Leases Receivable Disclosure [Line Items]
Gross loans	16,364	15,102
Mortgage, commercial [Member] \| Real Estate [Member]
Loans and Leases Receivable Disclosure [Line Items]
Gross loans	167,223	150,513
Mortgage, residential [Member] \| Real Estate [Member]
Loans and Leases Receivable Disclosure [Line Items]
Gross loans	165,865	149,856
Mortgage, farmland [Member] \| Real Estate [Member]
Loans and Leases Receivable Disclosure [Line Items]
Gross loans	3,754	4,179
Consumer installment loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Gross loans	$ 37,433	$ 31,979

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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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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