Total Expenditures and Amortization of Capitalized Computer Software (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Apr. 30, 2013	Apr. 30, 2012	Apr. 30, 2011
Capitalized Software [Line Items]
Total capitalized computer software development costs	$ 3,418	$ 2,731	$ 2,565
Total research and development expense	8,882	8,226	7,388
Total research and development expense and capitalized computer software development costs	12,300	10,957	9,953
Total amortization of capitalized computer software development costs	$ 2,501	$ 2,502	$ 1,892

For each income statement presented, the amount charged to expense for amortization of capitalized computer software costs.

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The aggregate costs incurred (1) in a planned search or critical investigation aimed at discovery of new knowledge with the hope that such knowledge will be useful in developing a new product or service, a new process or technique, or in bringing about a significant improvement to an existing product or process; or (2) to translate research findings or other knowledge into a plan or design for a new product or process or for a significant improvement to an existing product or process whether intended for sale or the entity's use, during the reporting period charged to research and development projects, including the costs of developing computer software up to the point in time of achieving technological feasibility, and costs allocated in accounting for a business combination to in-process projects deemed to have no alternative future use.

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