Summary of Significant Accounting Policies - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Jul. 31, 2013 Customer	Jul. 31, 2012 Customer
Significant Accounting Policies [Line Items]
Number of client accounted for more than 10% of account receivables	0
Number of client accounted for more than 10% of revenue	0	0
General and administrative	$ 8,929	$ 15,677
Research and development	9,116	7,699
Bad Debts
Significant Accounting Policies [Line Items]
General and administrative		200
Information Technology
Significant Accounting Policies [Line Items]
Research and development		$ 700

- Definition

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.

+ References+ Details