Aggregate Changes in Balance of Unrecognized Tax Benefits (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Apr. 30, 2013	Apr. 30, 2012	Apr. 30, 2011
Schedule of Unrecognized Tax Benefits [Line Items]
Beginning Balance	$ 539	$ 369	$ 174
Gross increases	862	9
Gross decreases		(68)
Gross increases	330	232	195
Gross decreases
Lapse of statute of limitations	(2)	(3)
Ending Balance	$ 1,729	$ 539	$ 369

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The gross amount of unrecognized tax benefits pertaining to uncertain tax positions taken in tax returns as of the balance sheet date.

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-Name Accounting Standards Codification

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The gross amount of decreases in unrecognized tax benefits resulting from tax positions that have been or will be taken in the tax return for the current period, excluding amounts pertaining to examined tax returns.

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The gross amount of decreases in unrecognized tax benefits resulting from tax positions taken in prior period tax returns, excluding amounts pertaining to examined tax returns.

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