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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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