ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (INCOME STATEMENT CLASSIFICATION TABLE) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Presentation of Income Statement Reclassifications [Line Items]
Sales Revenue Services Net	$ 453,081	$ 392,515	$ 885,294	$ 786,871
Benefit from (provision for) income taxes	(11,039)	(7,345)	(21,238)	(14,811)
Net income	33,549	13,614	58,234	34,090
Accumulated Other Comprehensive Income (Loss)
Presentation of Income Statement Reclassifications [Line Items]
Net Income (Loss) - Other			96	2,682
Derivative Valuation, Net of Tax
Presentation of Income Statement Reclassifications [Line Items]
Net Income (Loss) - Other			(168)	2,583
Reclassification from accumulated other comprehensive income
Presentation of Income Statement Reclassifications [Line Items]
Cost of services	(147)	(55)	(294)	(110)
Net Income (Loss) - Other	(132)	(49)	(264)	(99)
Reclassification from accumulated other comprehensive income | Tax effect
Presentation of Income Statement Reclassifications [Line Items]
Benefit from (provision for) income taxes	(21)	273	(62)	955
Provision for income taxes - Other	15	6	30	11
Reclassification from accumulated other comprehensive income | Derivative Valuation, Net of Tax
Presentation of Income Statement Reclassifications [Line Items]
Net income	58	(738)	168	(2,583)
Foreign Exchange Forward | Reclassification from accumulated other comprehensive income | Foreign Currency Translation Adjustment
Presentation of Income Statement Reclassifications [Line Items]
Sales Revenue Services Net	$ 79	$ (1,011)	$ 230	$ (3,538)