LOANS AND ALLOWANCE FOR LOAN LOSSES - Receivables Past Due (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual	$ 17,324	$ 12,043
Loans Past Due 90 Days or More and Still Accruing	29	13
Past Due	14,076	17,873
Loans Not Past Due	1,300,714	1,184,191
Loans	1,315,582	1,203,482
30 - 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	7,639	4,969
60 - 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	2,605	6,383
90 Days or More Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	3,832	6,521
Commercial, and Agricultural
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	199,576	177,027
Commercial mortgages:
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	646,174	570,156
Residential Mortgages
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual	3,160	4,201
Loans Past Due 90 Days or More and Still Accruing	0	0
Past Due	3,812	4,919
Loans Not Past Due	191,125	193,951
Loans	194,937	198,965
Residential Mortgages | 30 - 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	1,399	2,100
Residential Mortgages | 60 - 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	939	436
Residential Mortgages | 90 Days or More Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	1,474	2,383
Consumer Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	274,895	257,334
Construction | Commercial mortgages:
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual	135	19
Loans Past Due 90 Days or More and Still Accruing	0	0
Past Due	0	1,177
Loans Not Past Due	45,688	45,333
Loans	45,688	46,510
Construction | Commercial mortgages: | 30 - 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0	0
Construction | Commercial mortgages: | 60 - 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0	1,177
Construction | Commercial mortgages: | 90 Days or More Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0	0
Commercial mortgages | Commercial mortgages:
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual	6,520	5,454
Loans Past Due 90 Days or More and Still Accruing	0	0
Past Due	3,262	7,524
Loans Not Past Due	596,432	514,799
Loans	600,486	523,646
Commercial mortgages | Commercial mortgages: | 30 - 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	2,399	652
Commercial mortgages | Commercial mortgages: | 60 - 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	115	4,460
Commercial mortgages | Commercial mortgages: | 90 Days or More Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	748	2,412
Credit cards | Consumer Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual	0	0
Loans Past Due 90 Days or More and Still Accruing	24	11
Past Due	50	23
Loans Not Past Due	1,466	1,453
Loans	1,516	1,476
Credit cards | Consumer Loans | 30 - 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	17	3
Credit cards | Consumer Loans | 60 - 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	9	9
Credit cards | Consumer Loans | 90 Days or More Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	24	11
Home equity lines and loans | Consumer Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual	1,310	1,670
Loans Past Due 90 Days or More and Still Accruing	0	0
Past Due	1,279	1,376
Loans Not Past Due	99,599	97,477
Loans	100,878	98,853
Home equity lines and loans | Consumer Loans | 30 - 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	265	227
Home equity lines and loans | Consumer Loans | 60 - 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	31	0
Home equity lines and loans | Consumer Loans | 90 Days or More Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	983	1,149
Indirect Consumer Loans | Consumer Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual	935	654
Loans Past Due 90 Days or More and Still Accruing	0	0
Past Due	2,887	2,602
Loans Not Past Due	150,645	137,391
Loans	153,532	139,993
Indirect Consumer Loans | Consumer Loans | 30 - 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	1,822	1,773
Indirect Consumer Loans | Consumer Loans | 60 - 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	484	287
Indirect Consumer Loans | Consumer Loans | 90 Days or More Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	581	542
Direct consumer loans | Consumer Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual	14	45
Loans Past Due 90 Days or More and Still Accruing	0	0
Past Due	78	83
Loans Not Past Due	18,891	16,929
Loans	18,969	17,012
Direct consumer loans | Consumer Loans | 30 - 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	48	54
Direct consumer loans | Consumer Loans | 60 - 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	28	7
Direct consumer loans | Consumer Loans | 90 Days or More Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	2	22
Loans acquired with deteriorated credit quality
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual	792	1,418
Loans	792	1,418
Loans acquired with deteriorated credit quality | Commercial, and Agricultural
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	0	0
Loans acquired with deteriorated credit quality | Commercial mortgages:
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	792	1,323
Loans acquired with deteriorated credit quality | Residential Mortgages
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual	0	95
Loans	0	95
Loans acquired with deteriorated credit quality | Consumer Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	0	0
Loans acquired with deteriorated credit quality | Construction | Commercial mortgages:
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual	0	0
Loans	0	0
Loans acquired with deteriorated credit quality | Commercial mortgages | Commercial mortgages:
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual	792	1,323
Loans	792	1,323
Loans acquired with deteriorated credit quality | Credit cards | Consumer Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual	0	0
Loans	0	0
Loans acquired with deteriorated credit quality | Home equity lines and loans | Consumer Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual	0	0
Loans	0	0
Loans acquired with deteriorated credit quality | Indirect Consumer Loans | Consumer Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual	0	0
Loans	0	0
Loans acquired with deteriorated credit quality | Direct consumer loans | Consumer Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual	0	0
Loans	0	0
Commercial and industrial | Commercial, and Agricultural
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual	5,250	0
Loans Past Due 90 Days or More and Still Accruing	5	2
Past Due	2,708	169
Loans Not Past Due	196,322	176,497
Loans	199,030	176,666
Commercial and industrial | Commercial, and Agricultural | 30 - 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	1,689	160
Commercial and industrial | Commercial, and Agricultural | 60 - 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	999	7
Commercial and industrial | Commercial, and Agricultural | 90 Days or More Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	20	2
Commercial and industrial | Loans acquired with deteriorated credit quality | Commercial, and Agricultural
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual	0	0
Loans	0	0
Agricultural | Commercial, and Agricultural
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0	0
Loans Not Past Due	546	361
Loans	546	361
Agricultural | Commercial, and Agricultural | 30 - 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0	0
Agricultural | Commercial, and Agricultural | 60 - 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0	0
Agricultural | Commercial, and Agricultural | 90 Days or More Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0	0
Agricultural | Loans acquired with deteriorated credit quality | Commercial, and Agricultural
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual	0	0
Loans	$ 0	$ 0