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LOANS AND ALLOWANCE FOR LOAN LOSSES - Summary of Impaired Loans (Details) - USD ($) $ in Thousands | 9 Months Ended | 12 Months Ended
--- | --- | ---
Sep. 30, 2018 | Sep. 30, 2017 | Dec. 31, 2017
Unpaid Principal Balance [Abstract] |  |  |
Unpaid Principal Balance, With no related allowance recorded | $ 9,817 |  | $ 5,717
Unpaid Principal Balance, With related allowance recorded | 2,009 |  | 623
Unpaid Principal Balance | 11,826 |  | 6,340
Recorded Investment [Abstract] |  |  |
Recorded Investment, With no related allowance recorded | 9,817 |  | 5,717
Recorded Investment, With related allowance recorded | 2,009 |  | 623
Recorded Investment | 11,826 |  | 6,340
Related Allowance [Abstract] |  |  |
Related Allowance | 454 |  | 134
Average Recorded Investment [Abstract] |  |  |
Average Recorded Investment, With no related allowance recorded | 7,773 |  | 6,786
Average Recorded Investment, With related allowance recorded | 1,070 |  | 1,953
Average Recorded Investment | 8,843 |  | 8,739
Interest income | 0 | $ 0 |
Cash-based interest income | 0 | $ 0 |
Commercial and industrial |  |  |
Unpaid Principal Balance [Abstract] |  |  |
Unpaid Principal Balance, With no related allowance recorded | 786 |  | 437
Unpaid Principal Balance, With related allowance recorded | 798 |  | 26
Recorded Investment [Abstract] |  |  |
Recorded Investment, With no related allowance recorded | 786 |  | 437
Recorded Investment, With related allowance recorded | 798 |  | 26
Related Allowance [Abstract] |  |  |
Related Allowance | 315 |  | 17
Average Recorded Investment [Abstract] |  |  |
Average Recorded Investment, With no related allowance recorded | 889 |  | 434
Average Recorded Investment, With related allowance recorded | 252 |  | 315
Construction and development |  |  |
Unpaid Principal Balance [Abstract] |  |  |
Unpaid Principal Balance, With no related allowance recorded | 1,684 |  | 0
Unpaid Principal Balance, With related allowance recorded |  |  | 0
Recorded Investment [Abstract] |  |  |
Recorded Investment, With no related allowance recorded | 1,684 |  | 0
Recorded Investment, With related allowance recorded |  |  | 0
Related Allowance [Abstract] |  |  |
Related Allowance |  |  | 0
Average Recorded Investment [Abstract] |  |  |
Average Recorded Investment, With no related allowance recorded | 334 |  | 311
Average Recorded Investment, With related allowance recorded |  |  | 7
Commercial real estate |  |  |
Unpaid Principal Balance [Abstract] |  |  |
Unpaid Principal Balance, With no related allowance recorded | 5,399 |  | 3,979
Unpaid Principal Balance, With related allowance recorded | 961 |  | 279
Recorded Investment [Abstract] |  |  |
Recorded Investment, With no related allowance recorded | 5,399 |  | 3,979
Recorded Investment, With related allowance recorded | 961 |  | 279
Related Allowance [Abstract] |  |  |
Related Allowance | 61 |  | 27
Average Recorded Investment [Abstract] |  |  |
Average Recorded Investment, With no related allowance recorded | 4,863 |  | 4,230
Average Recorded Investment, With related allowance recorded | 470 |  | 505
Farmland |  |  |
Unpaid Principal Balance [Abstract] |  |  |
Unpaid Principal Balance, With no related allowance recorded | 73 |  | 6
Unpaid Principal Balance, With related allowance recorded | 145 |  | 157
Recorded Investment [Abstract] |  |  |
Recorded Investment, With no related allowance recorded | 73 |  | 6
Recorded Investment, With related allowance recorded | 145 |  | 157
Related Allowance [Abstract] |  |  |
Related Allowance | 74 |  | 85
Average Recorded Investment [Abstract] |  |  |
Average Recorded Investment, With no related allowance recorded | 67 |  | 90
Average Recorded Investment, With related allowance recorded | 149 |  | 131
1-4 family residential |  |  |
Unpaid Principal Balance [Abstract] |  |  |
Unpaid Principal Balance, With no related allowance recorded | 1,466 |  | 681
Unpaid Principal Balance, With related allowance recorded | 105 |  | 161
Recorded Investment [Abstract] |  |  |
Recorded Investment, With no related allowance recorded | 1,466 |  | 681
Recorded Investment, With related allowance recorded | 105 |  | 161
Related Allowance [Abstract] |  |  |
Related Allowance | 4 |  | 5
Average Recorded Investment [Abstract] |  |  |
Average Recorded Investment, With no related allowance recorded | 1,077 |  | 1,096
Average Recorded Investment, With related allowance recorded | 129 |  | 754
Multi-family residential |  |  |
Unpaid Principal Balance [Abstract] |  |  |
Unpaid Principal Balance, With no related allowance recorded | 0 |  | 217
Unpaid Principal Balance, With related allowance recorded |  |  | 0
Recorded Investment [Abstract] |  |  |
Recorded Investment, With no related allowance recorded | 0 |  | 217
Recorded Investment, With related allowance recorded |  |  | 0
Related Allowance [Abstract] |  |  |
Related Allowance |  |  | 0
Average Recorded Investment [Abstract] |  |  |
Average Recorded Investment, With no related allowance recorded | 71 |  | 180
Average Recorded Investment, With related allowance recorded |  |  | 19
Consumer |  |  |
Unpaid Principal Balance [Abstract] |  |  |
Unpaid Principal Balance, With no related allowance recorded |  |  | 0
Unpaid Principal Balance, With related allowance recorded |  |  | 0
Recorded Investment [Abstract] |  |  |
Recorded Investment, With no related allowance recorded |  |  | 0
Recorded Investment, With related allowance recorded |  |  | 0
Related Allowance [Abstract] |  |  |
Related Allowance |  |  | 0
Average Recorded Investment [Abstract] |  |  |
Average Recorded Investment, With no related allowance recorded |  |  | 61
Average Recorded Investment, With related allowance recorded |  |  | 42
Agricultural |  |  |
Unpaid Principal Balance [Abstract] |  |  |
Unpaid Principal Balance, With no related allowance recorded | 409 |  | 397
Unpaid Principal Balance, With related allowance recorded | 0 |  | 0
Recorded Investment [Abstract] |  |  |
Recorded Investment, With no related allowance recorded | 409 |  | 397
Recorded Investment, With related allowance recorded | 0 |  | 0
Related Allowance [Abstract] |  |  |
Related Allowance | 0 |  | 0
Average Recorded Investment [Abstract] |  |  |
Average Recorded Investment, With no related allowance recorded | 472 |  | 384
Average Recorded Investment, With related allowance recorded | $ 70 |  | $ 180

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