SHARE BASED COMPENSATION - Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Weighted Average Exercise Price Per Share:
Beginning balance, weighted average exercise price per share (in dollars per share	$ 19.48
Granted, weighted average exercise price per share (in dollars per share)	21.22
Forfeited, weighted average exercise price per share (in dollars per share	21.81
Ending balance, weighted average exercise price per share (in dollars per share	19.54	$ 19.48
Options exercisable, weighted average exercise price per share (in dollars per share)	$ 0.00
Weighted Average Remaining Contractual Term (in years)	9 years 11 months 1 day	9 years 11 months 19 days
Aggregate Intrinsic Value	$ (5,615)	$ 8,944
Time Vesting
Shares Under Option (in shares):
Outstanding balance, beginning of period (in shares)	5,110,747
Granted (in shares)	298,394
Forfeited (in shares)	(103,766)
Outstanding balance, end of period (in shares)	5,305,375	5,110,747
Options exercisable (in shares)	0
Performance Based Vesting
Shares Under Option (in shares):
Outstanding balance, beginning of period (in shares)	0
Granted (in shares)	39,050
Forfeited (in shares)	(22,314)
Outstanding balance, end of period (in shares)	16,736	0
Options exercisable (in shares)	0