Schedule of Pension Plans Weighted-Average Asset Allocation and Range of Target Allocation (Detail)	12 Months Ended
Mar. 31, 2016	Mar. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Percentage of Plan Assets at March 31	100.00%	100.00%
Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Range of Target Allocation - Minimum	40.00%
Range of Target Allocation - Maximum	60.00%
Percentage of Plan Assets at March 31	66.00%	61.00%
Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Range of Target Allocation - Minimum	35.00%
Range of Target Allocation - Maximum	60.00%
Percentage of Plan Assets at March 31	33.00%	36.00%
Other [Member]
Defined Benefit Plan Disclosure [Line Items]
Range of Target Allocation - Minimum	0.00%
Range of Target Allocation - Maximum	5.00%
Percentage of Plan Assets at March 31	1.00%	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 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

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-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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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=58740216&loc=d3e2446-114920

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