EARNINGS PER SHARE AND ACCUMULATED OTHER COMPREHENSIVE INCOME - Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Sep. 30, 2018	Jun. 30, 2018	Sep. 30, 2017	Jun. 30, 2017	Sep. 30, 2018
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Accumulated other comprehensive loss - beginning balance		$ (286,094)			$ (286,094)
Net current period other comprehensive income	$ (8,097)	(27,824)	$ 10,928	$ 10,070
Accumulated other comprehensive loss - ending balance	(322,015)				(322,015)
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Accumulated other comprehensive loss - beginning balance		(286,094)			(286,094)
Other comprehensive income before reclassification					(34,763)
Reclassified from accumulated other comprehensive income					(1,158)
Net current period other comprehensive income					(35,921)
Foreign exchange rate impact	0				0
Accumulated other comprehensive loss - ending balance	(322,015)				(322,015)
Currency Translation Adjustments | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Accumulated other comprehensive loss - beginning balance		(79,066)			(79,066)
Other comprehensive income before reclassification					(37,171)
Reclassified from accumulated other comprehensive income					0
Net current period other comprehensive income					(37,171)
Foreign exchange rate impact	(16,378)				(16,378)
Accumulated other comprehensive loss - ending balance	(132,615)				(132,615)
Pension Liability Adjustments | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Accumulated other comprehensive loss - beginning balance		(206,682)			(206,682)
Other comprehensive income before reclassification					0
Reclassified from accumulated other comprehensive income					0
Net current period other comprehensive income					0
Foreign exchange rate impact	16,378				16,378
Accumulated other comprehensive loss - ending balance	(190,304)				(190,304)
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Accumulated other comprehensive loss - beginning balance		$ (346)			(346)
Other comprehensive income before reclassification					2,408
Reclassified from accumulated other comprehensive income					(1,158)
Net current period other comprehensive income					1,250
Foreign exchange rate impact	0				0
Accumulated other comprehensive loss - ending balance	$ 904				$ 904