Consolidated Statements of Comprehensive Income (Loss) (Parenthetical) - USD ($) $ in Thousands		12 Months Ended
		Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Change in pension liability and postretirement obligations, tax		$ (6,442)	$ 4,197	$ 12,684
Change in derivatives qualifying as hedges, tax		900	430	233
Unrealized holding gain arising during the period, tax	[1]	(93)	43	(234)
Reclassification adjustment for (loss) gain included in net income, tax	[1]	56	83	723
Pension Plans
Change in pension liability and postretirement obligations, tax		(6,043)	4,635	12,409
Postretirement Benefit Plans
Change in pension liability and postretirement obligations, tax		(317)	(372)	233
Defined Benefit Postretirement Life Insurance
Change in pension liability and postretirement obligations, tax		$ (82)	$ (66)	$ 42

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