LOANS AND ALLOWANCE FOR LOAN LOSSES - Summary of Impaired Loans (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Unpaid Principal Balance [Abstract]
Unpaid Principal Balance, With no related allowance recorded	$ 6,535		$ 5,717
Unpaid Principal Balance, With related allowance recorded	1,094		623
Unpaid Principal Balance	7,629		6,340
Recorded Investment [Abstract]
Recorded Investment, With no related allowance recorded	6,535		5,717
Recorded Investment, With related allowance recorded	1,094		623
Recorded Investment	7,629		6,340
Related Allowance [Abstract]
Related Allowance	175		134
Average Recorded Investment [Abstract]
Average Recorded Investment, With no related allowance recorded	1,559		6,786
Average Recorded Investment, With related allowance recorded	179		1,953
Average Recorded Investment	1,738		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	791		437
Unpaid Principal Balance, With related allowance recorded	25		26
Recorded Investment [Abstract]
Recorded Investment, With no related allowance recorded	791		437
Recorded Investment, With related allowance recorded	25		26
Related Allowance [Abstract]
Related Allowance	12		17
Average Recorded Investment [Abstract]
Average Recorded Investment, With no related allowance recorded	144		434
Average Recorded Investment, With related allowance recorded	6		315
Construction and development
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			311
Average Recorded Investment, With related allowance recorded			7
Commercial real estate
Unpaid Principal Balance [Abstract]
Unpaid Principal Balance, With no related allowance recorded	4,270		3,979
Unpaid Principal Balance, With related allowance recorded	648		279
Recorded Investment [Abstract]
Recorded Investment, With no related allowance recorded	4,270		3,979
Recorded Investment, With related allowance recorded	648		279
Related Allowance [Abstract]
Related Allowance	69		27
Average Recorded Investment [Abstract]
Average Recorded Investment, With no related allowance recorded	1,065		4,230
Average Recorded Investment, With related allowance recorded	100		505
Farmland
Unpaid Principal Balance [Abstract]
Unpaid Principal Balance, With no related allowance recorded	79		6
Unpaid Principal Balance, With related allowance recorded	151		157
Recorded Investment [Abstract]
Recorded Investment, With no related allowance recorded	79		6
Recorded Investment, With related allowance recorded	151		157
Related Allowance [Abstract]
Related Allowance	80		85
Average Recorded Investment [Abstract]
Average Recorded Investment, With no related allowance recorded	13		90
Average Recorded Investment, With related allowance recorded	38		131
1-4 family residential
Unpaid Principal Balance [Abstract]
Unpaid Principal Balance, With no related allowance recorded	687		681
Unpaid Principal Balance, With related allowance recorded	113		161
Recorded Investment [Abstract]
Recorded Investment, With no related allowance recorded	687		681
Recorded Investment, With related allowance recorded	113		161
Related Allowance [Abstract]
Related Allowance	3		5
Average Recorded Investment [Abstract]
Average Recorded Investment, With no related allowance recorded	170		1,096
Average Recorded Investment, With related allowance recorded	9		754
Multi-family residential
Unpaid Principal Balance [Abstract]
Unpaid Principal Balance, With no related allowance recorded	212		217
Unpaid Principal Balance, With related allowance recorded			0
Recorded Investment [Abstract]
Recorded Investment, With no related allowance recorded	212		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	53		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	496		397
Unpaid Principal Balance, With related allowance recorded	157		0
Recorded Investment [Abstract]
Recorded Investment, With no related allowance recorded	496		397
Recorded Investment, With related allowance recorded	157		0
Related Allowance [Abstract]
Related Allowance	11		0
Average Recorded Investment [Abstract]
Average Recorded Investment, With no related allowance recorded	114		384
Average Recorded Investment, With related allowance recorded	$ 26		$ 180