Schedule of Minimum and Maximum Market Value of Plan Assets (Detail)	12 Months Ended
Mar. 31, 2016
Equity Securities
Schedule of Pension and Other Postretirement Plan Assets by Fair Value [Line Items]
Minimum market value objective for plan assets	55.00%
Maximum market value objective for plan assets	75.00%
Debt Securities
Schedule of Pension and Other Postretirement Plan Assets by Fair Value [Line Items]
Minimum market value objective for plan assets	25.00%
Maximum market value objective for plan assets	45.00%
Investment Grade Bonds
Schedule of Pension and Other Postretirement Plan Assets by Fair Value [Line Items]
Minimum market value objective for plan assets	0.00%
Maximum market value objective for plan assets	20.00%
Cash and Cash Equivalents
Schedule of Pension and Other Postretirement Plan Assets by Fair Value [Line Items]
Minimum market value objective for plan assets	0.00%
Maximum market value objective for plan assets	10.00%

Schedule of Pension and Other Postretirement Plan Assets by Fair Value [Line Items]

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- Definition

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 5
-Subparagraph (c)(i)
-URI http://asc.fasb.org/extlink&oid=58740216&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)(i)
-URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920

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Target allocation minimum 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=58740216&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=58740216&loc=d3e2446-114920

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