ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (Schedule of Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	$ 839,667	$ 751,443	$ 704,322
Other comprehensive (loss) income before reclassifications	32,256
Less: Income (loss) reclassified from accumulated other comprehensive income (loss)	(1,091)
Total other comprehensive income (loss), net of tax	33,347	(9,252)	(24,414)
Ending Balance	962,306	839,667	751,443
Gains and Losses on Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	1,071
Other comprehensive (loss) income before reclassifications	(2,122)
Less: Income (loss) reclassified from accumulated other comprehensive income (loss)	1,928
Total other comprehensive income (loss), net of tax	(4,050)
Ending Balance	(2,979)	1,071
Defined Benefit Pension Items
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(36)
Other comprehensive (loss) income before reclassifications	(57)
Less: Income (loss) reclassified from accumulated other comprehensive income (loss)	0
Total other comprehensive income (loss), net of tax	(57)
Ending Balance	(93)	(36)
Foreign Currency Items
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(58,189)
Other comprehensive (loss) income before reclassifications	37,454
Less: Income (loss) reclassified from accumulated other comprehensive income (loss)	0
Total other comprehensive income (loss), net of tax	37,454
Ending Balance	(20,735)	(58,189)
Short-term Investment
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	0
Other comprehensive (loss) income before reclassifications	(3,019)
Less: Income (loss) reclassified from accumulated other comprehensive income (loss)	(3,019)
Total other comprehensive income (loss), net of tax	0
Ending Balance	0	0
AOCI Attributable to Parent
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(57,154)	(47,902)	(23,488)
Total other comprehensive income (loss), net of tax	33,347	(9,252)
Ending Balance	$ (23,807)	$ (57,154)	$ (47,902)