Results from Discontinued Operations (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended	9 Months Ended
Jan. 31, 2014	Jan. 31, 2015	Jan. 31, 2014
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenues from discontinued operations	$ 4,397	$ 2,535	$ 13,039
Income from discontinued operations before income taxes	691	303	1,810
Income tax expense	261	23	682
Net income from discontinued operations	430	280	1,128
Loss on disposal of discontinued operations, net of tax		(1,537)
Income (loss) from discontinued operations, net of tax	$ 430	$ (1,257)	$ 1,128

Amount of gain (loss), after tax expense or benefit and not previously recognized, resulting from the sale of a business component.

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Pretax income (loss) from operations of a business component (exclusive of any gain (loss) on disposal, or provision therefore) during the reporting period, until its disposal.

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After tax income (loss) from operations of a business component (exclusive of any gain (loss) on disposal, or provision therefore) during the reporting period, until its disposal.

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Income tax expense or benefit attributable to Income or Loss from discontinued operations during the phase-out period.

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Amount of sales or other form of revenues attributable to the disposal group, including a component of the entity (discontinued operation), during the reporting period.

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Amount of income (loss) from a disposal group, net of income tax before extraordinary items allocable to noncontrolling interests. Includes, net of tax, income (loss) from operations during the phase-out period, gain (loss) on disposal, provision (or any reversals of earlier provisions) for loss on disposal, and adjustments of a prior period gain (loss) on disposal.

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