Stockholders' Deficit - Schedule of Changes in Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands		3 Months Ended			6 Months Ended
		Sep. 30, 2020	Sep. 30, 2019		Sep. 30, 2020	Sep. 30, 2019
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Balance	[1]	$ (1,047,381)	$ (557,919)		$ (781,264)	$ (573,313)
Total other comprehensive income (loss)		13,778	(76,157)	[1]	21,062	(76,586)	[1]
Balance	[1]	(1,064,357)	(590,824)		(1,064,357)	(590,824)
Currency Translation Adjustment [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Balance		(61,126)	(51,289)		(62,045)	(48,606)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax		7,282	(6,227)		8,201	(8,910)
Total other comprehensive income (loss)		7,282	(6,227)		8,201	(8,910)
Balance		(53,844)	(57,516)		(53,844)	(57,516)
Unrealized Gains and Losses on Derivative Instruments [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Balance		(2,203)	(1,449)		(4,303)	(1,130)
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax		2,772	245		6,430	340
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Net of Tax		(541)	(1,323)		(2,099)	(1,737)
Total other comprehensive income (loss)		2,231	(1,078)		4,331	(1,397)
Balance		28	(2,527)		28	(2,527)
Defined Benefit Pension Plans and Other Postretirement Benefits [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Balance		(675,835)	(463,702)		(680,100)	(466,275)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax			(122,971)			(122,971)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax		4,265	54,119		8,530	56,692
Total other comprehensive income (loss)		4,265	(68,852)		8,530	(66,279)
Balance		(671,570)	(532,554)		(671,570)	(532,554)
Accumulated Other Comprehensive Income (Loss) [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Balance	[1]	(739,164)	(516,440)		(746,448)	(516,011)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax		10,054	(128,953)		14,631	(131,541)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax		3,724	52,796		6,431	54,955
Total other comprehensive income (loss)		13,778	(76,157)		21,062	(76,586)
Balance	[1]	$ (725,386)	$ (592,597)		$ (725,386)	$ (592,597)

[1] As adjusted; refer to Note 1.