Schedule II Valuation and Qualifying Accounts (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Apr. 30, 2014	Apr. 30, 2013	Apr. 30, 2012
Allowance for doubtful accounts, customer and other
Valuation and Qualifying Accounts Disclosure [Line Items]
Beginning Balance	$ 2,371	$ 788	$ 381
Additions	2,626	2,290	1,083
Deductions	(2,673)	(707)	(676)
Ending Balance	2,324	2,371	788
Valuation allowance for deferred tax assets
Valuation and Qualifying Accounts Disclosure [Line Items]
Beginning Balance	37,902	19,854	12,391
Additions	16,223	20,588	7,463
Deductions	(1,391)	(2,540)
Ending Balance	$ 52,734	$ 37,902	$ 19,854