Basis of Presentation and Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)	12 Months Ended
	Apr. 30, 2013	Apr. 30, 2012	Apr. 30, 2011
Significant Accounting Policies [Line Items]
Foreign currency transaction gains and losses	$ 400,000	$ (400,000)	$ 200,000
Allowance for doubtful accounts	2,668,000	788,000
Share based compensation expense	$ 22,453,000	$ 7,710,000	$ 4,681,000