DERIVATIVE FINANCIAL INSTRUMENTS - Components of the Gain or Loss on Derivatives that Quality as a Cash Flow Hedging Relationship (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Gain (Loss) on Derivatives in Cash Flow Hedging Relationship
Amount of gains (losses) reclassified from accumulated other comprehensive income (loss) in the next twelve months	$ 500
Cash flow hedges
Gain (Loss) on Derivatives in Cash Flow Hedging Relationship
Amount of Gains (Losses) Deferred in Accumulated Other Comprehensive Income (Loss) on Derivatives	2,967	$ 3,582
Amount and Location of Gains (Losses) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income (Loss)	(205)	(318)
Amount and Location of (Losses) Recognized in Income (Loss) on Derivatives	0	0
Cash flow hedges | Foreign currency swaps
Gain (Loss) on Derivatives in Cash Flow Hedging Relationship
Amount of Gains (Losses) Deferred in Accumulated Other Comprehensive Income (Loss) on Derivatives	2,967	3,582
Amount and Location of Gains (Losses) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income (Loss)	(205)	(318)
Amount and Location of (Losses) Recognized in Income (Loss) on Derivatives	$ 0	$ 0