STOCK OPTIONS - Schedule of Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 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)	15,000	9,000
Exercised (in shares)		(2,010)
Forfeited (in shares)		(1,000)
Balance (in shares)	486,442	346,367	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)	31.84	26.00
Exercised (in USD per share)		11.94
Forfeited (in USD per share)		24.00
Balance (in USD per share)	$ 25.19	$ 23.56	$ 24.98	$ 23.43
Weighted-Average Remaining Contractual Life in Years
Outstanding	7 years 1 month 21 days	7 years 2 months 9 days	7 years 3 months 18 days	7 years 4 months 2 days
Granted	9 years 10 months 17 days	9 years 11 months 16 days
Exercised		3 years 29 days
Forfeited		5 years 6 months 18 days
Aggregate Intrinsic Value
Outstanding	$ 3,952	$ 844	$ 2,696	$ 194
Granted	26	0
Exercised	$ 0	28
Forfeited		$ 2
Exercisable
Outstanding (in shares)	140,644	92,667
Weighted-average exercise price (in USD per share)	$ 23.61	$ 22.91
Weighted-Average Remaining Contractual Life in Years	5 years 8 months 16 days	6 years 5 months 16 days
Aggregate Intrinsic Value	$ 1,364	$ 287