STOCK OPTIONS - Schedule of 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)	471,442	340,377	340,377
Granted (in shares)	59,000	109,200
Exercised (in shares)	(2,000)	(7,033)
Forfeited (in shares)	(1,600)	(6,000)
Balance (in shares)	526,842	436,544	471,442	340,377
Weighted-Average Exercise Price
Outstanding at beginning of year (in USD per share)	$ 24.98	$ 23.43	$ 23.43
Granted (in USD per share)	32.66	27.00
Exercised (in USD per share)	23.00	11.94
Forfeited (in USD per share)	23.00	23.17
Balance (in USD per share)	$ 25.85	$ 24.51	$ 24.98	$ 23.43
Weighted-Average Remaining Contractual Life in Years
Outstanding	7 years 1 month 21 days	7 years 7 months 17 days	7 years 3 months 18 days	7 years 4 months 2 days
Granted	9 years 10 months 2 days	9 years 10 months 24 days
Exercised	6 years 9 months 18 days	4 years 8 months 23 days
Forfeited	6 years 9 months 18 days	7 years 4 months 17 days
Aggregate Intrinsic Value
Outstanding	$ 3,740	$ 3,277	$ 2,696	$ 194
Granted	24	548
Exercised	20	141
Forfeited	$ 16	$ 53
Exercisable
Outstanding (in shares)	166,384	117,484
Weighted-average exercise price (in USD per share)	$ 23.95	$ 24.11
Weighted-Average Remaining Contractual Life in Years	5 years 10 months 21 days	7 years 4 days
Aggregate Intrinsic Value	$ 1,496	$ 930