LOANS AND ALLOWANCE FOR LOAN LOSSES - Allowances (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017	Jun. 30, 2018	Dec. 31, 2017
Allowance for loan losses, by portfolio segment [Roll Forward]
Beginning balance	$ 21,390	$ 14,960	$ 21,161	$ 14,253	$ 14,253
Charge-offs	(4,303)	(447)	(4,875)	(892)
Recoveries	196	170	288	282
Net recoveries (charge-offs)	(4,107)	(277)	(4,587)	(610)
Provision	2,362	421	3,071	1,461
Ending balance	19,645	15,104	19,645	15,104	21,161
Ending allowance balance attributable to loans [Abstract]
Individually evaluated for impairment						$ 1,738	$ 5,937
Collectively evaluated for impairment						17,907	15,195
Total ending allowance balance	21,390	14,960	21,161	14,253	14,253	19,645	21,161
Loans [Abstract]
Loans individually evaluated for impairment						9,342	13,926
Loans collectively evaluated for impairment						1,328,768	1,300,864
Total recorded investment in loans						1,338,110	1,315,582
Loans acquired with deteriorated credit quality
Allowance for loan losses, by portfolio segment [Roll Forward]
Beginning balance			29
Ending balance					29
Ending allowance balance attributable to loans [Abstract]
Total ending allowance balance			29		29		29
Loans [Abstract]
Total recorded investment in loans						0	792
Commercial and agricultural:
Allowance for loan losses, by portfolio segment [Roll Forward]
Beginning balance	7,003	1,650	6,976	1,589	1,589
Charge-offs	(3,624)	(2)	(3,644)	(7)
Recoveries	11	36	21	61
Net recoveries (charge-offs)	(3,613)	34	(3,623)	54
Provision	1,579	199	1,616	240
Ending balance	4,969	1,883	4,969	1,883	6,976
Ending allowance balance attributable to loans [Abstract]
Individually evaluated for impairment						1,285	5,135
Collectively evaluated for impairment						3,684	1,841
Total ending allowance balance	7,003	1,650	6,976	1,589	1,589	4,969	6,976
Loans [Abstract]
Loans individually evaluated for impairment						2,017	6,133
Loans collectively evaluated for impairment						192,040	193,443
Total recorded investment in loans						194,057	199,576
Commercial and agricultural: | Loans acquired with deteriorated credit quality
Allowance for loan losses, by portfolio segment [Roll Forward]
Beginning balance			0
Ending balance					0
Ending allowance balance attributable to loans [Abstract]
Total ending allowance balance			0		0		0
Loans [Abstract]
Total recorded investment in loans							0
Commercial Mortgages
Allowance for loan losses, by portfolio segment [Roll Forward]
Beginning balance	8,640	7,749	8,514	7,270	7,270
Charge-offs	(145)	0	(145)	0
Recoveries	1	2	2	3
Net recoveries (charge-offs)	(144)	2	(143)	3
Provision	244	27	369	505
Ending balance	8,740	7,778	8,740	7,778	8,514
Ending allowance balance attributable to loans [Abstract]
Individually evaluated for impairment						453	802
Collectively evaluated for impairment						8,287	7,683
Total ending allowance balance	8,640	7,749	8,514	7,270	7,270	8,740	8,514
Loans [Abstract]
Loans individually evaluated for impairment						6,847	7,302
Loans collectively evaluated for impairment						661,711	638,080
Total recorded investment in loans						668,558	646,174
Commercial Mortgages | Loans acquired with deteriorated credit quality
Allowance for loan losses, by portfolio segment [Roll Forward]
Beginning balance			29
Ending balance					29
Ending allowance balance attributable to loans [Abstract]
Total ending allowance balance			29		29		29
Loans [Abstract]
Total recorded investment in loans							792
Residential mortgages
Allowance for loan losses, by portfolio segment [Roll Forward]
Beginning balance	1,407	1,512	1,316	1,523	1,523
Charge-offs	(71)	(48)	(165)	(60)
Recoveries	0	13	5	30
Net recoveries (charge-offs)	(71)	(35)	(160)	(30)
Provision	109	40	289	24
Ending balance	1,445	1,517	1,445	1,517	1,316
Ending allowance balance attributable to loans [Abstract]
Individually evaluated for impairment						0	0
Collectively evaluated for impairment						1,445	1,316
Total ending allowance balance	1,407	1,512	1,316	1,523	1,523	1,445	1,316
Loans [Abstract]
Loans individually evaluated for impairment						417	427
Loans collectively evaluated for impairment						193,514	194,510
Total recorded investment in loans						193,931	194,937
Residential mortgages | Loans acquired with deteriorated credit quality
Allowance for loan losses, by portfolio segment [Roll Forward]
Beginning balance			0
Ending balance					0
Ending allowance balance attributable to loans [Abstract]
Total ending allowance balance			0		0		0
Loans [Abstract]
Total recorded investment in loans						0	0
Consumer loans:
Allowance for loan losses, by portfolio segment [Roll Forward]
Beginning balance	4,340	4,049	4,355	3,871	3,871
Charge-offs	(463)	(397)	(921)	(825)
Recoveries	184	119	260	188
Net recoveries (charge-offs)	(279)	(278)	(661)	(637)
Provision	430	155	797	692
Ending balance	4,491	3,926	4,491	3,926	4,355
Ending allowance balance attributable to loans [Abstract]
Individually evaluated for impairment						0	0
Collectively evaluated for impairment						4,491	4,355
Total ending allowance balance	$ 4,340	$ 4,049	4,355	$ 3,871	3,871	4,491	4,355
Loans [Abstract]
Loans individually evaluated for impairment						61	64
Loans collectively evaluated for impairment						281,503	274,831
Total recorded investment in loans						$ 281,564	274,895
Consumer loans: | Loans acquired with deteriorated credit quality
Allowance for loan losses, by portfolio segment [Roll Forward]
Beginning balance			0
Ending balance					0
Ending allowance balance attributable to loans [Abstract]
Total ending allowance balance			$ 0		$ 0		0
Loans [Abstract]
Total recorded investment in loans							$ 0