DERIVATIVES (INCOME STATEMENT CLASSIFICATION) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Sales Revenue Services Net	$ 395,507	$ 364,936	$ 1,182,378	$ 1,090,038
Other nonoperating income expense	2,713	989	5,376	(10,786)
Designated as Hedging Instruments [Member] | Foreign Exchange [Member] | Cash Flow [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain or (loss) recognized in other comprehensive income (loss) - effective portion, net of tax:	(793)	(2,981)	(3,376)	(10,439)
Designated as Hedging Instruments [Member] | Foreign Exchange [Member] | Cash Flow [Member] | Reclassification from accumulated other comprehensive income | Revenue
Derivative Instruments, Gain (Loss) [Line Items]
Sales Revenue Services Net	(1,087)	(4,085)	(4,625)	(14,300)
Not Designated as Hedging Instruments [Member] | Foreign Exchange [Member] | Fair Value [Member] | Reclassification from accumulated other comprehensive income | Other income (expense), net
Derivative Instruments, Gain (Loss) [Line Items]
Other nonoperating income expense	$ 57	$ (956)	$ (1,160)	$ (6,651)