Changes in Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
Apr. 30, 2015	Apr. 30, 2014	Apr. 30, 2013
Income Taxes [Line Items]
Unrecognized tax benefits, beginning of year	$ 2,701	$ 3,400
Settlement with tax authority	(497)	(1,946)
Additions based on tax positions related to the current year	219	279	$ 1,454
Additions based on tax positions related to prior years		968	1,946
Unrecognized tax benefits, end of year	$ 2,423	$ 2,701	$ 3,400

Income Taxes [Line Items]

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- Definition

Amount of unrecognized tax benefits pertaining to uncertain tax positions taken in tax returns.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 10

-Section 50

-Paragraph 15A

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=6907707&loc=SL6600010-109319

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Unrecognized Tax Benefit

-URI http://asc.fasb.org/extlink&oid=6527854

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- Definition

Amount of decrease in unrecognized tax benefits resulting from settlements with taxing authorities.

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- Definition

Amount of increase in unrecognized tax benefits resulting from tax positions that have been or will be taken in current period tax return.

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Amount of increase in unrecognized tax benefits resulting from tax positions taken in prior period tax returns.

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