ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (INCOME STATEMENT CLASSIFICATION TABLE) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Presentation of Income Statement Reclassifications [Line Items]
Sales Revenue Services Net	$ 375,249	$ 338,277
Interest Expense.	6,459	2,318
Benefit from (provision for) income taxes	(2,102)	(5,391)
Net income	5,932	20,167
Accumulated Other Comprehensive Income (Loss)
Presentation of Income Statement Reclassifications [Line Items]
Net Income (Loss) - Other	3,994	4,253
Derivative Valuation, Net of Tax
Presentation of Income Statement Reclassifications [Line Items]
Net Income (Loss) - Other	3,893	4,136
Reclassification from accumulated other comprehensive income
Presentation of Income Statement Reclassifications [Line Items]
Cost of services	(112)	(130)
Net Income (Loss) - Other	(101)	(117)
Reclassification from accumulated other comprehensive income | Derivative Valuation, Net of Tax
Presentation of Income Statement Reclassifications [Line Items]
Net income	(3,893)	(4,136)
Reclassification from accumulated other comprehensive income | Tax effect
Presentation of Income Statement Reclassifications [Line Items]
Benefit from (provision for) income taxes	1,439	2,759
Provision for income taxes - Other	11	13
Foreign Exchange Forward | Reclassification from accumulated other comprehensive income
Presentation of Income Statement Reclassifications [Line Items]
Sales Revenue Services Net	$ (5,332)	(6,806)
Interest Rate | Reclassification from accumulated other comprehensive income | Loss on interest rate swaps [Member]
Presentation of Income Statement Reclassifications [Line Items]
Interest Expense.		$ (89)