LOANS AND ALLOWANCE FOR LOAN LOSSES - Allowance (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Changes in the allowance for loan losses
Balance at beginning of period	$ 9,101	$ 8,006	$ 6,223
Charge-offs	(1,497)	(2,557)	(747)
Recoveries	101	20	37
Provision	2,173	3,632	2,493
Balance at end of period	9,878	9,101	8,006
Individually evaluated for impairment	1,188	543	1,013
Collectively evaluated for impairment	8,690	8,558	6,993
Commercial
Changes in the allowance for loan losses
Balance at beginning of period	7,181	6,066	4,363
Charge-offs	(1,138)	(1,995)	(708)
Recoveries	39	8	20
Provision	1,722	3,102	2,391
Balance at end of period	7,804	7,181	6,066
Individually evaluated for impairment	1,172	376	708
Collectively evaluated for impairment	6,632	6,805	5,358
Residential
Changes in the allowance for loan losses
Balance at beginning of period	990	1,095	962
Charge-offs	(141)	(124)	(28)
Recoveries	40	2	2
Provision	230	17	159
Balance at end of period	1,119	990	1,095
Individually evaluated for impairment	0	122	276
Collectively evaluated for impairment	1,119	868	819
Home Equity
Changes in the allowance for loan losses
Balance at beginning of period	728	715	691
Charge-offs	(109)	(100)	(5)
Recoveries	4	9	4
Provision	82	104	25
Balance at end of period	705	728	715
Individually evaluated for impairment	0	36	28
Collectively evaluated for impairment	705	692	687
Consumer
Changes in the allowance for loan losses
Balance at beginning of period	202	130	207
Charge-offs	(109)	(338)	(6)
Recoveries	18	1	11
Provision	139	409	(82)
Balance at end of period	250	202	130
Individually evaluated for impairment	16	9	1
Collectively evaluated for impairment	$ 234	$ 193	$ 129