COMPREHENSIVE INCOME - Schedule of Changes in Accumulated Other Comprehensive Income by Component (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2017 USD ($)
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	$ 839,667
Other comprehensive (loss) income	30,393
Amounts reclassified from accumulated other comprehensive income	2,978
Net current-period other comprehensive (loss) income	33,371
Ending balance	913,116
Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	1,071
Other comprehensive (loss) income	(290)
Amounts reclassified from accumulated other comprehensive income	(41)
Net current-period other comprehensive (loss) income	(331)
Ending balance	740
Defined Benefit Pension Items
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(36)
Other comprehensive (loss) income	(22)
Amounts reclassified from accumulated other comprehensive income	0
Net current-period other comprehensive (loss) income	(22)
Ending balance	(58)
Foreign Currency Items
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(58,189)
Other comprehensive (loss) income	33,724
Amounts reclassified from accumulated other comprehensive income	0
Net current-period other comprehensive (loss) income	33,724
Ending balance	(24,465)
Short-term Investment
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	0
Other comprehensive (loss) income	(3,019)
Amounts reclassified from accumulated other comprehensive income	3,019
Net current-period other comprehensive (loss) income	0
Ending balance	0
Total
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(57,154)
Ending balance	$ (23,783)