Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Net income (loss)	$ 254,529	$ 47,989	$ (53,629)
Other comprehensive income (loss):
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax	41,217	(5,708)
Other comprehensive income (loss)	38,797	(10,387)	(2,629)
Total comprehensive income (loss)	293,326	37,602	(56,258)
Foreign currency translation gains (losses), net of tax
Other comprehensive income (loss):
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax	35,054	(15,284)	1,860
Other comprehensive income (loss)	35,054	(15,284)
Defined benefit pension plans, net of tax
Other comprehensive income (loss):
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax	167	(536)
Amounts reclassified out of OCI	167	163	5,202
Other comprehensive income (loss)	(167)	163
Defined benefit post-retirement plan adjustments
Other comprehensive income (loss):
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax	(255)	228
Amounts reclassified out of OCI	(255)	20	(45)
Other comprehensive income (loss)	255	20
Equity interest in investee’s other comprehensive income (loss)
Other comprehensive income (loss):
Amounts reclassified out of OCI	5,584	1,440	(8,276)
Other comprehensive income (loss)	5,584	1,440
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member]
Other comprehensive income (loss):
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax	(667)	(8,444)
Other comprehensive income (loss)	$ (1,753)	$ 3,274	$ (1,370)