Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands		3 Months Ended			6 Months Ended
		Sep. 30, 2020	Sep. 30, 2019		Sep. 30, 2020	Sep. 30, 2019
Income Statement [Abstract]
Net sales		$ 481,815	$ 772,110	[1]	$ 976,892	$ 1,502,341	[1]
Operating costs and expenses:
Cost of sales (exclusive of depreciation shown separately below)		382,072	622,236	[1]	775,915	1,204,469	[1]
Selling, general and administrative		56,239	66,201	[1]	113,442	128,538	[1]
Depreciation and amortization		22,098	30,219	[1]	50,700	74,269	[1]
Impairment of long-lived assets					252,382
Restructuring		13,237	5,782	[1]	28,676	8,746	[1]
Legal judgment gain, net of expenses	[1]		(5,400)			(5,400)
Loss (gain) on sale of assets and businesses		747	(7,965)	[1]	747	(4,829)	[1]
Operating Expenses		474,393	711,073	[1]	1,221,862	1,405,793	[1]
Operating income (loss)		7,422	61,037	[1]	(244,970)	96,548	[1]
Non-service defined benefit income		(12,427)	(27,824)	[1]	(24,843)	(41,226)	[1]
Interest expense and other, net		52,506	35,400	[1]	87,463	62,891	[1]
(Loss) income from continuing operations before income taxes		(32,657)	53,461	[1]	(307,590)	74,883	[1]
Income tax expense		832	11,227	[1]	1,685	15,725	[1]
Net (loss) income		$ (33,489)	$ 42,234	[1]	$ (309,275)	$ 59,158	[1]
(Loss) earnings per share—basic:
Net (loss) income		$ (0.64)	$ 0.84	[1]	$ (5.95)	$ 1.18	[1]
Weighted average common shares outstanding—basic		52,011	49,987	[1]	51,941	49,927	[1]
(Loss) earnings per share—diluted:
Net (loss) income		$ (0.64)	$ 0.84	[1]	$ (5.95)	$ 1.17	[1]
Weighted average common shares outstanding—diluted		52,011	50,460	[1]	51,941	50,385	[1]
Dividends declared and paid per common share	[1]		$ 0.04			$ 0.08

[1] As adjusted; refer to Note 1.