Computations of Loss per Share Applicable to Common Stockholders (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Jul. 31, 2014		Jul. 31, 2013
Schedule Of Computation Of Basic And Diluted Earnings Per Common Share [Line Items]
Net loss from continuing operations	$ (10,308)		$ (17,646)
Net income (loss) from discontinued operations, net of tax	(1,257)		278
Net loss applicable to common stockholders	$ (11,565)		$ (17,368)
Continuing operations	$ (0.13)		$ (0.23)
Discontinued operations	$ (0.02)
Basic and diluted loss per share	$ (0.15)		$ (0.23)
Basic and diluted weighted average number of shares outstanding	77,766		73,983
Outstanding stock options
Potentially dilutive securities (1):
Outstanding stock options	922	[1]	2,987	[1]
Restricted Stock
Potentially dilutive securities (1):
Outstanding stock options	170	[1]	188	[1]

[1] The impact of potentially dilutive securities on earnings per share is anti-dilutive in a period of net loss.