Discount Rate Assumptions in Computation of Accumulated Postretirement Benefit Obligation (Details)	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation [Abstract]
Accumulated postretirement benefit obligation	3.99%	4.49%	3.77%

The interest rate used to adjust for the time value of money for the plan.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (k)(1)

-URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920

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