LOANS AND ALLOWANCE FOR LOAN LOSSES - Receivables Past Due (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual	$ 15,099	$ 12,254
Loans Past Due 90 Days or More and Still Accruing	11	19
Aging of the recorded investment in loans past due [Abstract]
Past Due	10,534	14,367
Loans Not Past Due	1,292,498	1,301,242
Total recorded investment in loans	1,303,032	1,315,609
30 - 59 Days Past Due
Aging of the recorded investment in loans past due [Abstract]
Past Due	7,985	10,688
60 - 89 Days Past Due
Aging of the recorded investment in loans past due [Abstract]
Past Due	352	1,207
90 Days or More Past Due
Aging of the recorded investment in loans past due [Abstract]
Past Due	2,197	2,472
Commercial and agricultural
Aging of the recorded investment in loans past due [Abstract]
Total recorded investment in loans	205,137	203,412
Commercial Mortgages
Aging of the recorded investment in loans past due [Abstract]
Total recorded investment in loans	660,158	662,988
Commercial Mortgages | Construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual	101	109
Loans Past Due 90 Days or More and Still Accruing	0	0
Aging of the recorded investment in loans past due [Abstract]
Past Due	3,187	0
Loans Not Past Due	43,548	54,626
Total recorded investment in loans	46,735	54,626
Commercial Mortgages | Construction | 30 - 59 Days Past Due
Aging of the recorded investment in loans past due [Abstract]
Past Due	3,187	0
Commercial Mortgages | Construction | 60 - 89 Days Past Due
Aging of the recorded investment in loans past due [Abstract]
Past Due	0	0
Commercial Mortgages | Construction | 90 Days or More Past Due
Aging of the recorded investment in loans past due [Abstract]
Past Due	0	0
Commercial Mortgages | Commercial mortgages
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual	8,680	5,529
Loans Past Due 90 Days or More and Still Accruing	0	0
Aging of the recorded investment in loans past due [Abstract]
Past Due	834	6,600
Loans Not Past Due	612,589	601,762
Total recorded investment in loans	613,423	608,362
Commercial Mortgages | Commercial mortgages | 30 - 59 Days Past Due
Aging of the recorded investment in loans past due [Abstract]
Past Due	555	6,273
Commercial Mortgages | Commercial mortgages | 60 - 89 Days Past Due
Aging of the recorded investment in loans past due [Abstract]
Past Due	0	158
Commercial Mortgages | Commercial mortgages | 90 Days or More Past Due
Aging of the recorded investment in loans past due [Abstract]
Past Due	279	169
Residential mortgages
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual	2,550	2,655
Loans Past Due 90 Days or More and Still Accruing	0	0
Aging of the recorded investment in loans past due [Abstract]
Past Due	3,433	3,746
Loans Not Past Due	178,507	179,479
Total recorded investment in loans	181,940	183,225
Residential mortgages | 30 - 59 Days Past Due
Aging of the recorded investment in loans past due [Abstract]
Past Due	2,249	2,204
Residential mortgages | 60 - 89 Days Past Due
Aging of the recorded investment in loans past due [Abstract]
Past Due	158	516
Residential mortgages | 90 Days or More Past Due
Aging of the recorded investment in loans past due [Abstract]
Past Due	1,026	1,026
Consumer Loans
Aging of the recorded investment in loans past due [Abstract]
Total recorded investment in loans	255,797	265,984
Consumer Loans | Credit cards
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual	0	0
Loans Past Due 90 Days or More and Still Accruing	0	9
Aging of the recorded investment in loans past due [Abstract]
Past Due	0	13
Loans Not Past Due	0	1,437
Total recorded investment in loans	0	1,450
Consumer Loans | Credit cards | 30 - 59 Days Past Due
Aging of the recorded investment in loans past due [Abstract]
Past Due	0	1
Consumer Loans | Credit cards | 60 - 89 Days Past Due
Aging of the recorded investment in loans past due [Abstract]
Past Due	0	3
Consumer Loans | Credit cards | 90 Days or More Past Due
Aging of the recorded investment in loans past due [Abstract]
Past Due	0	9
Consumer Loans | Home equity lines and loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual	1,022	1,183
Loans Past Due 90 Days or More and Still Accruing	0	0
Aging of the recorded investment in loans past due [Abstract]
Past Due	862	1,106
Loans Not Past Due	96,519	97,360
Total recorded investment in loans	97,381	98,466
Consumer Loans | Home equity lines and loans | 30 - 59 Days Past Due
Aging of the recorded investment in loans past due [Abstract]
Past Due	372	279
Consumer Loans | Home equity lines and loans | 60 - 89 Days Past Due
Aging of the recorded investment in loans past due [Abstract]
Past Due	16	97
Consumer Loans | Home equity lines and loans | 90 Days or More Past Due
Aging of the recorded investment in loans past due [Abstract]
Past Due	474	730
Consumer Loans | Indirect consumer loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual	632	693
Loans Past Due 90 Days or More and Still Accruing	0	0
Aging of the recorded investment in loans past due [Abstract]
Past Due	1,260	2,266
Loans Not Past Due	141,495	147,540
Total recorded investment in loans	142,755	149,806
Consumer Loans | Indirect consumer loans | 30 - 59 Days Past Due
Aging of the recorded investment in loans past due [Abstract]
Past Due	855	1,511
Consumer Loans | Indirect consumer loans | 60 - 89 Days Past Due
Aging of the recorded investment in loans past due [Abstract]
Past Due	121	319
Consumer Loans | Indirect consumer loans | 90 Days or More Past Due
Aging of the recorded investment in loans past due [Abstract]
Past Due	284	436
Consumer Loans | Direct consumer loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual	33	37
Loans Past Due 90 Days or More and Still Accruing	0	0
Aging of the recorded investment in loans past due [Abstract]
Past Due	85	204
Loans Not Past Due	15,576	16,058
Total recorded investment in loans	15,661	16,262
Consumer Loans | Direct consumer loans | 30 - 59 Days Past Due
Aging of the recorded investment in loans past due [Abstract]
Past Due	47	120
Consumer Loans | Direct consumer loans | 60 - 89 Days Past Due
Aging of the recorded investment in loans past due [Abstract]
Past Due	9	53
Consumer Loans | Direct consumer loans | 90 Days or More Past Due
Aging of the recorded investment in loans past due [Abstract]
Past Due	29	31
Commercial and industrial | Commercial and agricultural
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual	2,081	2,048
Loans Past Due 90 Days or More and Still Accruing	11	10
Aging of the recorded investment in loans past due [Abstract]
Past Due	840	416
Loans Not Past Due	203,970	202,667
Total recorded investment in loans	204,810	203,083
Commercial and industrial | Commercial and agricultural | 30 - 59 Days Past Due
Aging of the recorded investment in loans past due [Abstract]
Past Due	713	284
Commercial and industrial | Commercial and agricultural | 60 - 89 Days Past Due
Aging of the recorded investment in loans past due [Abstract]
Past Due	22	61
Commercial and industrial | Commercial and agricultural | 90 Days or More Past Due
Aging of the recorded investment in loans past due [Abstract]
Past Due	105	71
Agricultural | Commercial and agricultural
Aging of the recorded investment in loans past due [Abstract]
Past Due	33	16
Loans Not Past Due	294	313
Total recorded investment in loans	327	329
Agricultural | Commercial and agricultural | 30 - 59 Days Past Due
Aging of the recorded investment in loans past due [Abstract]
Past Due	7	16
Agricultural | Commercial and agricultural | 60 - 89 Days Past Due
Aging of the recorded investment in loans past due [Abstract]
Past Due	26	0
Agricultural | Commercial and agricultural | 90 Days or More Past Due
Aging of the recorded investment in loans past due [Abstract]
Past Due	$ 0	$ 0