CONSOLIDATED STATEMENT OF COMPREHENSIVE INCOME (parenthetical) - USD ($) $ in Thousands	12 Months Ended
Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2014
Statement of Income and Comprehensive Income [Abstract]
Change in pension and post retirement benefits adjustment tax	$ 2,179	$ 13,140	$ 7,222

Amount of tax (expense) benefit, before reclassification adjustments, related to (increase) decrease in accumulated other comprehensive (income) loss related to pension and other postretirement benefit plans.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=36458714&loc=d3e640-108580

Name:	us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansBeforeReclassificationAdjustmentsTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration