Employee Benefit Plans (Discount Rate Assumptions in Computation of Accumulated Postretirement Benefit Obligation) (Details)	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation [Abstract]
Accumulated postretirement benefit obligation	3.98%	3.94%	3.89%

Weighted average rate for present value of future retirement benefits cash flows, used to determine benefit obligation of defined benefit 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=82843861&loc=d3e1928-114920

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