Other Comprehensive Loss - Components Reclassified from AOCI to Earnings (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Pensions and other postretirement benefits
Reclassification Out Of Accumulated Other Comprehensive Income [Line Items]
Amounts reclassified from accumulated other comprehensive loss to net income, gross	$ 395	$ 366	$ 790	$ 732
Tax effects of amounts reclassified from accumulated other comprehensive loss to net income	(84)	(164)	(168)	(164)
Amounts reclassified from accumulated other comprehensive loss to net income, net	311	202	622	568
Actuarial loss
Reclassification Out Of Accumulated Other Comprehensive Income [Line Items]
Amounts reclassified from accumulated other comprehensive loss to net income, gross	560	533	1,120	1,066
Amortization of prior service cost
Reclassification Out Of Accumulated Other Comprehensive Income [Line Items]
Amounts reclassified from accumulated other comprehensive loss to net income, gross	(165)	(167)	(330)	(334)
Derivatives
Reclassification Out Of Accumulated Other Comprehensive Income [Line Items]
Amounts reclassified from accumulated other comprehensive loss to net income, gross	1,809	569	2,460	987
Tax effects of amounts reclassified from accumulated other comprehensive loss to net income	(379)	(119)	(516)	(207)
Amounts reclassified from accumulated other comprehensive loss to net income, net	$ 1,430	$ 450	$ 1,944	$ 780

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount before tax of reclassification adjustments of other comprehensive income (loss).

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Amount after tax of reclassification adjustments of other comprehensive income (loss).

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Amount of tax expense (benefit) of reclassification adjustment from accumulated other comprehensive income (loss).

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