Consolidated Statements of Comprehensive Income (Loss) (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Change in pension liability and postretirement obligations, tax	$ 2,097	$ (5,205)	$ (6,442)
Change in derivatives qualifying as hedges, tax	469	(1,519)	900
Unrealized holding gain arising during the period, tax	0	(124)	(93)
Reclassification adjustment for (loss) gain included in net income, tax	0	0	56
Pension Plans
Change in pension liability and postretirement obligations, tax	2,242	(4,981)	(6,043)
Postretirement Benefit Plans
Change in pension liability and postretirement obligations, tax	(126)	(153)	(317)
Defined Benefit Postretirement Life Insurance
Change in pension liability and postretirement obligations, tax	$ (18)	$ (70)	$ (82)

Amount of tax expense (benefit), after reclassification adjustments, of increase (decrease) in accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's increase (decrease) in deferred hedging gain (loss).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 10A
-Subparagraph (d)
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-Name Accounting Standards Codification
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Amount, after reclassification adjustment, of tax (expense) benefit for (increase) decrease in accumulated other comprehensive income of defined benefit plan.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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-SubTopic 10
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-SubTopic 10
-Section 45
-Paragraph 19
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Amount of tax expense (benefit) of reclassification adjustment from accumulated other comprehensive income of accumulated gain (loss) realized from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's deferred hedging gain (loss).

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