OTHER NONOPERATING EXPENSE, NET (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Other Income and Expenses [Abstract]
Interest income	$ 204	$ 110	$ 346	$ 187
Foreign currency exchange (loss) / gain, net	(6,054)	7,864	(1,788)	9,476
Change in fair value of derivatives (Note 12)	(1,101)	(1,100)	(1,329)	(732)
Loss on extinguishment of debt	(179)	0	(288)	0
Other income, net	194	34	171	209
Total other non-operating (expense) / income, net	$ (6,936)	$ 6,908	$ (2,888)	$ 9,140