STOCK OPTIONS - Schedule of Nonvested Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
Number of Shares
Outstanding at beginning of year (in shares)	336,798	250,700	250,700
Granted (in shares)	59,000	109,200
Vested (in shares)	(33,740)	(36,840)
Forfeited (in shares)	(1,600)	(4,000)
Balance (in shares)	360,458	319,060	336,798	250,700
Weighted-Average Exercise Price
Outstanding at beginning of year (in USD per share)	$ 25.54	$ 23.73	$ 23.73
Granted (in USD per share)	32.66	27.00
Vested (in USD per share)	25.30	25.40
Forfeited (in USD per share)	23.00	23.17
Balance (in USD per share)	$ 26.91	$ 24.66	$ 25.54	$ 23.73
Weighted-Average Remaining Contractual Life in Years
Outstanding	7 years 9 months	7 years 10 months 10 days	7 years 10 months 17 days	7 years 7 months 24 days
Granted	9 years 10 months 2 days	9 years 10 months 24 days
Vested	8 years 1 month 10 days	9 years 1 month 28 days
Forfeited	6 years 9 months 18 days	7 years 4 months 17 days
Aggregate Intrinsic Value
Outstanding	$ 1,747	$ 69	$ 69
Granted	24	548
Vested	258	244
Forfeited	16	53
Outstanding	$ 2,165	$ 2,347	$ 1,747	$ 69