ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (INCOME STATEMENT CLASSIFICATION TABLE) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Presentation of Income Statement Reclassifications [Line Items]
Sales Revenue Services Net	$ 539,219	$ 432,213
Benefit from (provision for) income taxes	(15,979)	(10,199)
Net income	55,024	24,685
Accumulated Other Comprehensive Income (Loss)
Presentation of Income Statement Reclassifications [Line Items]
Net Income (Loss) - Other	(987)	21
Derivative Valuation, Net of Tax
Presentation of Income Statement Reclassifications [Line Items]
Net Income (Loss) - Other	(1,059)	(110)
Reclassification from accumulated other comprehensive income
Presentation of Income Statement Reclassifications [Line Items]
Cost of services	(80)	(146)
Net Income (Loss) - Other	(72)	(131)
Reclassification from accumulated other comprehensive income | Tax effect
Presentation of Income Statement Reclassifications [Line Items]
Benefit from (provision for) income taxes	(372)	(41)
Provision for income taxes - Other	8	15
Reclassification from accumulated other comprehensive income | Derivative Valuation, Net of Tax
Presentation of Income Statement Reclassifications [Line Items]
Net income	1,059	110
Foreign Exchange Forward | Reclassification from accumulated other comprehensive income | Foreign Currency Translation Adjustment
Presentation of Income Statement Reclassifications [Line Items]
Sales Revenue Services Net	$ 1,431	$ 151