ALLOWANCE FOR CREDIT LOSSES - Charge-offs and recoveries by loan class and vintage (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Financing Receivable, Recorded Investment [Line Items]
Charge-offs	$ (272)	$ (567)
Recovery	520	262
Net (charge-offs) recoveries	248	(305)
Commercial and industrial
Financing Receivable, Recorded Investment [Line Items]
Charge-offs	(79)	(425)
Recovery	495	241
Net (charge-offs) recoveries	416	(184)
Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Charge-offs	(24)
Recovery		4
Net (charge-offs) recoveries	(24)	4
1-4 family residential
Financing Receivable, Recorded Investment [Line Items]
Charge-offs	(66)	(12)
Recovery	1	2
Net (charge-offs) recoveries	(65)	(10)
Consumer
Financing Receivable, Recorded Investment [Line Items]
Charge-offs	(103)	(87)
Recovery	11	15
Net (charge-offs) recoveries	(92)	(72)
Agriculture
Financing Receivable, Recorded Investment [Line Items]
Recovery	12
Net (charge-offs) recoveries	12
Other
Financing Receivable, Recorded Investment [Line Items]
Charge-offs		(43)
Recovery	1
Net (charge-offs) recoveries	1	$ (43)
2020.
Financing Receivable, Recorded Investment [Line Items]
Net (charge-offs) recoveries	10
2020. | Consumer
Financing Receivable, Recorded Investment [Line Items]
Recovery	10
Net (charge-offs) recoveries	10
2019.
Financing Receivable, Recorded Investment [Line Items]
Net (charge-offs) recoveries	(63)
2019. | Commercial and industrial
Financing Receivable, Recorded Investment [Line Items]
Recovery	2
Net (charge-offs) recoveries	2
2019. | 1-4 family residential
Financing Receivable, Recorded Investment [Line Items]
Charge-offs	(65)
Net (charge-offs) recoveries	(65)
2018.
Financing Receivable, Recorded Investment [Line Items]
Net (charge-offs) recoveries	84
2018. | Commercial and industrial
Financing Receivable, Recorded Investment [Line Items]
Recovery	92
Net (charge-offs) recoveries	92
2018. | Consumer
Financing Receivable, Recorded Investment [Line Items]
Charge-offs	(8)
Net (charge-offs) recoveries	(8)
2017.
Financing Receivable, Recorded Investment [Line Items]
Net (charge-offs) recoveries	(97)
2017. | Commercial and industrial
Financing Receivable, Recorded Investment [Line Items]
Charge-offs	(36)
Recovery	33
Net (charge-offs) recoveries	(3)
2017. | Consumer
Financing Receivable, Recorded Investment [Line Items]
Charge-offs	(95)
Net (charge-offs) recoveries	(95)
2017. | Other
Financing Receivable, Recorded Investment [Line Items]
Recovery	1
Net (charge-offs) recoveries	1
2016.
Financing Receivable, Recorded Investment [Line Items]
Net (charge-offs) recoveries	(11)
2016. | Commercial and industrial
Financing Receivable, Recorded Investment [Line Items]
Charge-offs	(42)
Recovery	19
Net (charge-offs) recoveries	(23)
2016. | Agriculture
Financing Receivable, Recorded Investment [Line Items]
Recovery	12
Net (charge-offs) recoveries	12
Prior.
Financing Receivable, Recorded Investment [Line Items]
Net (charge-offs) recoveries	132
Prior. | Commercial and industrial
Financing Receivable, Recorded Investment [Line Items]
Recovery	155
Net (charge-offs) recoveries	155
Prior. | Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Charge-offs	(24)
Net (charge-offs) recoveries	(24)
Prior. | 1-4 family residential
Financing Receivable, Recorded Investment [Line Items]
Charge-offs	(1)
Recovery	1
Prior. | Consumer
Financing Receivable, Recorded Investment [Line Items]
Recovery	1
Net (charge-offs) recoveries	1
Revolving Loans.
Financing Receivable, Recorded Investment [Line Items]
Net (charge-offs) recoveries	193
Revolving Loans. | Commercial and industrial
Financing Receivable, Recorded Investment [Line Items]
Charge-offs	(1)
Recovery	194
Net (charge-offs) recoveries	$ 193