LOANS AND ALLOWANCE FOR LOAN LOSSES - Summary of Loan Portfolio by Type of Loan (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Dec. 31, 2016
Loans held for investment:
Total loans	$ 1,651,863	$ 1,359,544	$ 1,307,375
Deferred loan fees	727	1,094
Less: Allowance for loan losses	(14,441)	(12,859)	(12,528)	$ (11,484)
Total net loans	1,638,149	1,347,779
Commercial and industrial
Loans held for investment:
Total loans	248,758	197,508	192,663
Less: Allowance for loan losses	(1,707)	(1,581)	(1,573)	(1,592)
Construction and development
Loans held for investment:
Total loans	229,307	196,774	201,067
Less: Allowance for loan losses	(1,843)	(1,724)	(1,923)	(1,161)
Commercial real estate
Loans held for investment:
Total loans	599,153	418,137	393,314
Less: Allowance for loan losses	(5,882)	(4,585)	(4,199)	(3,264)
Farmland
Loans held for investment:
Total loans	65,209	59,023	54,349
Less: Allowance for loan losses	(623)	(523)	(458)	(482)
1-4 family residential
Loans held for investment:
Total loans	392,456	374,371	365,889
Less: Allowance for loan losses	(2,891)	(3,022)	(3,089)	(3,960)
Multi-family residential
Loans held for investment:
Total loans	38,523	36,574	23,235
Less: Allowance for loan losses	(670)	(629)	(266)	(281)
Consumer
Loans held for investment:
Total loans	53,947	51,267	51,711
Less: Allowance for loan losses	(569)	(602)	(599)	(585)
Agricultural
Loans held for investment:
Total loans	24,184	25,596	24,449
Less: Allowance for loan losses	(247)	(187)	(407)	(153)
Overdrafts
Loans held for investment:
Total loans	326	294	698
Less: Allowance for loan losses	$ (9)	$ (6)	$ (14)	$ (6)

Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

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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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