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LOANS AND ALLOWANCE FOR LOAN LOSSES - Allowances (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018	Jun. 30, 2019	Dec. 31, 2018
Allowance for loan losses, by portfolio segment [Roll Forward]
Beginning balance	$ 19,745	$ 21,390	$ 18,944	$ 21,161	$ 21,161
Charge-offs	(405)	(4,303)	(853)	(4,875)
Recoveries	166	196	322	288
Net recoveries (charge-offs)	(239)	(4,107)	(531)	(4,587)
Provision	150	2,362	1,243	3,071
Ending balance	19,656	19,645	19,656	19,645	18,944
Ending allowance balance attributable to loans [Abstract]
Individually evaluated for impairment						$ 4,464	$ 2,189
Collectively evaluated for impairment						15,192	16,755
Total ending allowance balance	19,745	21,390	18,944	21,161	21,161	19,656	18,944
Loans [Abstract]
Loans individually evaluated for impairment						16,675	8,731
Loans collectively evaluated for impairment						1,275,748	1,306,878
Total recorded investment in loans						1,292,423	1,315,609
Commercial and Agricultural
Allowance for loan losses, by portfolio segment [Roll Forward]
Beginning balance	5,429	7,003	5,383	6,976	6,976
Charge-offs	(48)	(3,624)	(55)	(3,644)
Recoveries	4	11	15	21
Net recoveries (charge-offs)	(44)	(3,613)	(40)	(3,623)
Provision	91	1,579	133	1,616
Ending balance	5,476	4,969	5,476	4,969	5,383
Ending allowance balance attributable to loans [Abstract]
Individually evaluated for impairment						1,726	1,743
Collectively evaluated for impairment						3,750	3,640
Total ending allowance balance	5,429	7,003	5,383	6,976	6,976	5,476	5,383
Loans [Abstract]
Loans individually evaluated for impairment						2,074	2,128
Loans collectively evaluated for impairment						205,395	201,284
Total recorded investment in loans						207,469	203,412
Commercial Mortgages
Allowance for loan losses, by portfolio segment [Roll Forward]
Beginning balance	9,474	8,640	8,184	8,514	8,514
Charge-offs	0	(145)	0	(145)
Recoveries	1	1	2	2
Net recoveries (charge-offs)	1	(144)	2	(143)
Provision	70	244	1,359	369
Ending balance	9,545	8,740	9,545	8,740	8,184
Ending allowance balance attributable to loans [Abstract]
Individually evaluated for impairment						2,738	446
Collectively evaluated for impairment						6,807	7,738
Total ending allowance balance	9,474	8,640	8,184	8,514	8,514	9,545	8,184
Loans [Abstract]
Loans individually evaluated for impairment						14,056	6,146
Loans collectively evaluated for impairment						636,546	656,842
Total recorded investment in loans						650,602	662,988
Residential mortgages
Allowance for loan losses, by portfolio segment [Roll Forward]
Beginning balance	1,215	1,407	1,226	1,316	1,316
Charge-offs	(39)	(71)	(41)	(165)
Recoveries	45	0	45	5
Net recoveries (charge-offs)	6	(71)	4	(160)
Provision	8	109	(1)	289
Ending balance	1,229	1,445	1,229	1,445	1,226
Ending allowance balance attributable to loans [Abstract]
Individually evaluated for impairment						0	0
Collectively evaluated for impairment						1,229	1,226
Total ending allowance balance	1,215	1,407	1,226	1,316	1,316	1,229	1,226
Loans [Abstract]
Loans individually evaluated for impairment						385	402
Loans collectively evaluated for impairment						183,962	182,823
Total recorded investment in loans						184,347	183,225
Consumer Loans
Allowance for loan losses, by portfolio segment [Roll Forward]
Beginning balance	3,627	4,340	4,151	4,355	4,355
Charge-offs	(318)	(463)	(757)	(921)
Recoveries	116	184	260	260
Net recoveries (charge-offs)	(202)	(279)	(497)	(661)
Provision	(19)	430	(248)	797
Ending balance	3,406	4,491	3,406	4,491	4,151
Ending allowance balance attributable to loans [Abstract]
Individually evaluated for impairment						0	0
Collectively evaluated for impairment						3,406	4,151
Total ending allowance balance	$ 3,627	$ 4,340	$ 4,151	$ 4,355	$ 4,355	3,406	4,151
Loans [Abstract]
Loans individually evaluated for impairment						160	55
Loans collectively evaluated for impairment						249,845	265,929
Total recorded investment in loans						$ 250,005	$ 265,984

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