DERIVATIVES (INCOME STATEMENT CLASSIFICATION) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Derivative Instruments, Gain (Loss) [Line Items]
Sales Revenue Services Net	$ 539,219	$ 432,213
Other nonoperating income expense	(798)	3,396
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:	1,059	110
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	1,431	151
Not Designated as Hedging Instruments [Member] | Foreign Exchange [Member] | Fair Value [Member] | Other income (expense), net
Derivative Instruments, Gain (Loss) [Line Items]
Other nonoperating income expense	$ (337)	$ (330)