Basis of Presentation and Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)	12 Months Ended
	Apr. 30, 2014	Apr. 30, 2013	Apr. 30, 2012
Significant Accounting Policies [Line Items]
Foreign currency transaction gains and losses	$ 400,000	$ 400,000	$ (400,000)
Allowance for doubtful accounts	2,324,000	2,371,000
Stock-based expense	14,468,000	22,453,000	7,710,000
Bad Debts
Significant Accounting Policies [Line Items]
Prior period reclassification adjustment		2,900,000	1,100,000
Information Technology
Significant Accounting Policies [Line Items]
Prior period reclassification adjustment		$ 3,800,000	$ 2,100,000