EARNINGS PER SHARE AND ACCUMULATED OTHER COMPREHENSIVE INCOME - Accumulated Other Comprehensive Income (Details) $ in Thousands	6 Months Ended
	Sep. 30, 2017 USD ($)
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Balance as of March 31, 2017	$ 1,294,232
Net current period other comprehensive income	20,998
Balance as of September 30, 2017	1,233,028
Currency Translation Adjustments
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Balance as of March 31, 2017	(149,721)
Other comprehensive income before reclassification	20,998
Reclassified from accumulated other comprehensive income	0
Net current period other comprehensive income	20,998
Foreign exchange rate impact	16,431
Balance as of September 30, 2017	(112,292)
Pension Liability Adjustments
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Balance as of March 31, 2017	(178,556)
Other comprehensive income before reclassification	0
Reclassified from accumulated other comprehensive income	0
Net current period other comprehensive income	0
Foreign exchange rate impact	(16,431)
Balance as of September 30, 2017	(194,987)
Total
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Balance as of March 31, 2017	(328,277)
Other comprehensive income before reclassification	20,998
Reclassified from accumulated other comprehensive income	0
Net current period other comprehensive income	20,998
Foreign exchange rate impact	0
Balance as of September 30, 2017	$ (307,279)