Related-Party Transactions - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
Apr. 30, 2013	Apr. 30, 2012	Jan. 31, 2013
Related Party Transaction [Line Items]
Percentage of entity's voting stock owned by related party	10.00%	10.00%	10.00%
Affiliated Entity [Member]
Related Party Transaction [Line Items]
Total commitment payment of license	10.2
Payment for license fees	0.4	0.5
Operating lease expense related to license agreements included in research and development cost	0.4	0.4
Shareholder [Member]
Related Party Transaction [Line Items]
Percentage of investor own voting stock			4.60%
Recognized revenue from related party	13.4	19.4
Account receivables from related party	7.6		8.2

The aggregate amount of receivables to be collected from related parties where one party can exercise control or significant influence over another party; including affiliates, owners or officers and their immediate families, pension trusts, and so forth, at the financial statement date. which are usually due within one year (or one business cycle).

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Amount of revenue, fees and commissions earned from transactions between (a) a parent company and its subsidiaries; (b) subsidiaries of a common parent; (c) an entity and trusts for the benefit of employees, for example, but not limited to, pension and profit-sharing trusts that are managed by or under the trusteeship of the entity's management; (d) an entity and its principal, owners, management, or members of their immediate families; and (e) affiliates.

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