Basis of Presentation and Summary of Significant Accounting Policies - Additional Information (Detail)	12 Months Ended
	Apr. 30, 2015 USD ($) Customer	Apr. 30, 2014 USD ($) Customer	Apr. 30, 2013 USD ($)
Significant Accounting Policies [Line Items]
Foreign currency transaction gains and losses	$ (1,000,000)	$ 400,000	$ 400,000
Impairment charges recognized related to short-term investments	0	0	0
Allowance for doubtful accounts	$ 3,992,000	$ 2,324,000
Number of clients that accounted for more than 10% of account receivables | Customer	0	0
Number of clients that accounted for more than 10% of revenue | Customer	0	0
Stock-based expense	$ 12,802,000	$ 14,468,000	$ 22,453,000
Capitalized internal-use software development costs
Significant Accounting Policies [Line Items]
Estimated useful life	3 years