DERIVATIVE FINANCIAL INSTRUMENTS (Changes in the Fair Value of Derivative Instruments) (Details) - Foreign exchange contracts - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Designated as hedging instruments \| Cash Flow Hedging \| Cost of revenues (exclusive of depreciation and amortization)
Derivative Instruments, Gain (Loss) [Line Items]
Net gain/(loss) reclassified	$ 342	$ (937)	$ (110)	$ (937)
Designated as hedging instruments \| Cash Flow Hedging \| Accumulated other comprehensive loss
Derivative Instruments, Gain (Loss) [Line Items]
Change in fair value	1,984	(2,696)	5,983	(2,606)
Not designated as hedging instruments \| Foreign exchange loss
Derivative Instruments, Gain (Loss) [Line Items]
Net gain recognized	$ 0	$ 0	$ 0	$ 44

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The effective portion of net gain (loss) reclassified from accumulated other comprehensive income into income on derivative instruments designated and qualifying as hedging instruments.

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Amount of realized and unrealized gain (loss) of derivative instruments not designated or qualifying as hedging instruments.

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Amount before tax of increase (decrease) in accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's increase (decrease) in deferred hedging gain (loss).

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