LOANS AND ALLOWANCE FOR LOAN LOSSES - Summary of Impaired Loans (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2019	Dec. 31, 2018
Unpaid Principal Balance [Abstract]
Unpaid Principal Balance, With no related allowance recorded	$ 5,959	$ 8,356
Unpaid Principal Balance, With related allowance recorded	3,049	3,000
Unpaid Principal Balance	9,008	11,356
Recorded Investment [Abstract]
Recorded Investment, With no related allowance recorded	5,959	8,356
Recorded Investment, With related allowance recorded	3,049	3,000
Recorded Investment, With related allowance recorded	9,008	11,356
Related Allowance [Abstract]
Related Allowance	877	493
Average Recorded Investment [Abstract]
Average Recorded Investment, With no related allowance recorded	1,869	8,202
Average Recorded Investment, With related allowance recorded	895	1,348
Average Recorded Investment, With related allowance recorded	2,764	9,550
Commercial and industrial
Unpaid Principal Balance [Abstract]
Unpaid Principal Balance, With no related allowance recorded	326	837
Unpaid Principal Balance, With related allowance recorded	157	185
Recorded Investment [Abstract]
Recorded Investment, With no related allowance recorded	326	837
Recorded Investment, With related allowance recorded	157	185
Related Allowance [Abstract]
Related Allowance	57	64
Average Recorded Investment [Abstract]
Average Recorded Investment, With no related allowance recorded	83	842
Average Recorded Investment, With related allowance recorded	41	300
Construction and development
Unpaid Principal Balance [Abstract]
Unpaid Principal Balance, With no related allowance recorded	1,250	720
Unpaid Principal Balance, With related allowance recorded		530
Recorded Investment [Abstract]
Recorded Investment, With no related allowance recorded	1,250	720
Recorded Investment, With related allowance recorded		530
Related Allowance [Abstract]
Related Allowance		4
Average Recorded Investment [Abstract]
Average Recorded Investment, With no related allowance recorded	312	518
Average Recorded Investment, With related allowance recorded		44
Commercial real estate
Unpaid Principal Balance [Abstract]
Unpaid Principal Balance, With no related allowance recorded	2,700	5,168
Unpaid Principal Balance, With related allowance recorded	2,753	1,985
Recorded Investment [Abstract]
Recorded Investment, With no related allowance recorded	2,700	5,168
Recorded Investment, With related allowance recorded	2,753	1,985
Related Allowance [Abstract]
Related Allowance	746	341
Average Recorded Investment [Abstract]
Average Recorded Investment, With no related allowance recorded	1,107	5,138
Average Recorded Investment, With related allowance recorded	764	677
Farmland
Unpaid Principal Balance [Abstract]
Unpaid Principal Balance, With related allowance recorded	139	140
Recorded Investment [Abstract]
Recorded Investment, With related allowance recorded	139	140
Related Allowance [Abstract]
Related Allowance	74	78
Average Recorded Investment [Abstract]
Average Recorded Investment, With no related allowance recorded		62
Average Recorded Investment, With related allowance recorded	35	147
1-4 family residential
Unpaid Principal Balance [Abstract]
Unpaid Principal Balance, With no related allowance recorded	1,450	1,223
Unpaid Principal Balance, With related allowance recorded		160
Recorded Investment [Abstract]
Recorded Investment, With no related allowance recorded	1,450	1,223
Recorded Investment, With related allowance recorded		160
Related Allowance [Abstract]
Related Allowance		6
Average Recorded Investment [Abstract]
Average Recorded Investment, With no related allowance recorded	294	1,132
Average Recorded Investment, With related allowance recorded	55	128
Multi-family residential
Average Recorded Investment [Abstract]
Average Recorded Investment, With no related allowance recorded		54
Agricultural
Unpaid Principal Balance [Abstract]
Unpaid Principal Balance, With no related allowance recorded	233	408
Recorded Investment [Abstract]
Recorded Investment, With no related allowance recorded	233	408
Average Recorded Investment [Abstract]
Average Recorded Investment, With no related allowance recorded	$ 73	456
Average Recorded Investment, With related allowance recorded		$ 52

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