EQUITY-BASED COMPENSATION PLANS (NARRATIVE) (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2018	Jun. 30, 2017
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Equity-based compensation expense		$ 6,183	$ 4,836
Restricted Stock Units (RSUs) [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Equity-based compensation expense	$ 2,600	6,200
Unrecognized Compensation Expense	27,900	$ 27,900
Non-option Equity Awards Granted		466,102	696,093
Cost of Services
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Equity-based compensation expense	1,000	$ 2,400
Selling General And Administrative Expenses [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Equity-based compensation expense	$ 1,600	$ 3,800