EQUITY-BASED COMPENSATION PLANS (NARRATIVE) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Equity-based compensation expense	$ 3,100	$ 3,100	$ 9,663	$ 9,292
Restricted Stock Units (RSUs) [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Equity-based compensation expense	2,500	3,100	8,900	$ 9,300
Unrecognized Compensation Expense	18,300		$ 18,300
Non-option Equity Awards Granted			101,909	480,582
Performance Shares [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Equity-based compensation expense	600		$ 800
Share-based Compensation Arrangement by Share-based Payment Award, Description			During the six months ended June 30, 2019, the Company awarded performance restricted stock units ("PRSUs") that are subject to service and performance vesting conditions. If defined minimum targets are met, the annual value of the PRSUs issued will be between $0.4 million and $1.4 million and vest immediately. If the defined minimum targets are not met, then no shares will be issued. The award amounts are based on the Company's annual adjusted operating income for the fiscal years 2019, 2020, 2021. Each fiscal year's adjusted operating income will determine the award amount.
Cost of Services
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Equity-based compensation expense	1,000	1,100	$ 3,700	$ 3,500
Selling General And Administrative Expenses [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Equity-based compensation expense	$ 2,100	$ 2,000	$ 6,000	$ 5,800