LOANS AND ALLOWANCE FOR LOAN LOSSES - Loans by class modified as troubled debt restructurings (Details) $ in Thousands	12 Months Ended
Dec. 31, 2017 USD ($) item	Dec. 31, 2016 USD ($) item	Dec. 31, 2015 USD ($) item
Troubled debt restructurings
Total of troubled debt restructurings	$ 3,845	$ 6,474
Allocated specific reserves	405	508
Amounts Company has committed to lend to customers with outstanding loans classified as troubled debt restructurings	$ 0	$ 0
Loans by class modified as troubled debt restructurings
Number of Loans \| item	5	8	17
Pre-Modification Outstanding Recorded Investment	$ 610	$ 587	$ 2,139
Post-Modification Outstanding Recorded Investment	610	587	1,878
Increase in allowance for loan losses due to troubled debt restructurings	0	0	50
Charge offs due to troubled debt restructurings	$ 0	$ 0	$ 261
Commercial \| Agricultural
Loans by class modified as troubled debt restructurings
Number of Loans \| item		1
Pre-Modification Outstanding Recorded Investment		$ 89
Post-Modification Outstanding Recorded Investment		$ 89
Commercial \| Other
Loans by class modified as troubled debt restructurings
Number of Loans \| item		2
Pre-Modification Outstanding Recorded Investment		$ 298
Post-Modification Outstanding Recorded Investment		$ 298
Commercial \| Commercial and industrial
Loans by class modified as troubled debt restructurings
Number of Loans \| item			3
Pre-Modification Outstanding Recorded Investment			$ 216
Post-Modification Outstanding Recorded Investment			$ 216
Commercial real estate \| Other
Loans by class modified as troubled debt restructurings
Number of Loans \| item	1		9
Pre-Modification Outstanding Recorded Investment	$ 53		$ 1,664
Post-Modification Outstanding Recorded Investment	$ 53		$ 1,403
Commercial real estate \| Home equity
Loans by class modified as troubled debt restructurings
Number of Loans \| item			0
Residential \| 1-4 family
Loans by class modified as troubled debt restructurings
Number of Loans \| item	4	1	3
Pre-Modification Outstanding Recorded Investment	$ 557	$ 124	$ 215
Post-Modification Outstanding Recorded Investment	$ 557	$ 124	$ 215
Residential \| Home equity
Loans by class modified as troubled debt restructurings
Number of Loans \| item		4	2
Pre-Modification Outstanding Recorded Investment		$ 76	$ 44
Post-Modification Outstanding Recorded Investment		$ 76	$ 44
Minimum
Troubled debt restructurings
Period of modifications involving a reduction of the stated interest rate of the loan	60 months
Period of modifications involving an extension of the maturity date	6 months
Maximum
Troubled debt restructurings
Period of modifications involving a reduction of the stated interest rate of the loan	30 years
Period of modifications involving an extension of the maturity date	40 months

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Represents the period of modifications involving an extension of the maturity date at a stated rate of interest lower than the current market rate for new debt with similar risk.

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The amount of the outstanding recorded investment related to financing receivables that have been modified by troubled debt restructurings.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 40
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=25495931&loc=d3e18845-111554

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Recorded Investment
-URI http://asc.fasb.org/extlink&oid=65880944

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