REVENUES, Remaining Performance Obligation (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Contract assets	$ 0	$ 0
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2018-04-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Expected timing of satisfaction, period	9 months
Remaining performance obligation	$ 79,562
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Expected timing of satisfaction, period	1 year
Remaining performance obligation	$ 1,654