Condensed Consolidated Statements of Comprehensive Loss (Unaudited) - USD ($) $ in Thousands		3 Months Ended				6 Months Ended
		Sep. 30, 2020		Sep. 30, 2019		Sep. 30, 2020	Sep. 30, 2019
Statement Of Income And Comprehensive Income [Abstract]
Net (loss) income		$ (33,489)		$ 42,234	[1]	$ (309,275)	$ 59,158	[1]
Other comprehensive income (loss):
Foreign currency translation adjustment		7,282	[1]	(6,227)	[1]	8,201	(8,910)	[1]
Amounts arising during the period - net of tax (expense) benefit
Prior service cost, net of taxes of $0 and $0, respectively	[1]			(4,898)			(4,898)
Actuarial loss, net of taxes of $0 and $0, respectively	[1]			(118,073)			(118,073)
Reclassification to net (loss) income - net of expense (benefit)
Amortization of net loss, net of taxes of $0 and $0, respectively		5,298		5,174	[1]	10,596	9,189	[1]
Recognized prior service (credits) cost, net of taxes of $0 and $0, respectively		(1,033)		48,945	[1]	(2,066)	47,503	[1]
Total defined benefit pension plans and other postretirement benefits, net of taxes		4,265		(68,852)	[1]	8,530	(66,279)	[1]
Cash flow hedges:
Unrealized gain arising during the period, net of tax benefit of $0 and $0 respectively		2,772		245	[1]	6,430	340	[1]
Reclassification of loss included in net earnings, net of tax expense of $0 and $0 respectively		(541)		(1,323)	[1]	(2,099)	(1,737)	[1]
Net unrealized gain (loss) on cash flow hedges, net of tax		2,231		(1,078)	[1]	4,331	(1,397)	[1]
Total other comprehensive income (loss)		13,778		(76,157)	[1]	21,062	(76,586)	[1]
Total comprehensive loss		$ (19,711)		$ (33,923)	[1]	$ (288,213)	$ (17,428)	[1]

[1] As adjusted; refer to Note 1.