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Defined Benefit Pension Plans - Additional Information (Detail) - USD ($)	9 Months Ended
	Jan. 31, 2016	Jan. 31, 2015
Compensation and Retirement Disclosure [Abstract]
Company expected contributions remainder of fiscal year	$ 0
Contributions made by company	$ 64,000	$ 775,000

X

- References

No definition available.

+ Details

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- Definition

The increase in the fair value of plan assets from contributions made by the employer.

+ 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 (b)(3)
-URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920

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- Definition

Amount of benefits from a defined benefit plan expected to be paid in the remainder of the fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

No definition available.

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