Postretirement Benefit Plans (Target and Actual Allocation Percentages) (Details)	12 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Target allocation ranges, minimum	17.00%
Target allocation ranges, maximum	53.00%
Allocation in aggregate	36.00%	39.00%
Fixed Income [Member]
Defined Benefit Plan Disclosure [Line Items]
Target allocation ranges, minimum	47.00%
Target allocation ranges, maximum	77.00%
Allocation in aggregate	60.00%	57.00%
Real Estate [Member]
Defined Benefit Plan Disclosure [Line Items]
Target allocation ranges, minimum	0.00%
Target allocation ranges, maximum	15.00%
Allocation in aggregate	1.00%	1.00%
Other [Member]
Defined Benefit Plan Disclosure [Line Items]
Target allocation ranges, minimum	0.00%
Target allocation ranges, maximum	11.00%
Allocation in aggregate	3.00%	3.00%

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Target allocation maximum percentage of investments of this type to total plan assets presented on a weighted average basis.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (d)(i)

-URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 5

-Subparagraph (c)(i)

-URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e2446-114920

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- Definition

Target allocation minimum percentage of investments of this type to total plan assets presented on a weighted average basis.

+ References

+ Details

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- Definition

Percentage of fair value of investments (categorized by debt securities, equity securities, real estate and other plan assets) to the fair value of plan assets held.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 5

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e2446-114920

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (d)(1)

-URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920

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