Net Loss Per Share Applicable To Common Stockholders from Continuing Operations - Computations of Loss per Share Applicable to Common Stockholders (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended								12 Months Ended
		Apr. 30, 2015	Jan. 31, 2015	Oct. 31, 2014	Jul. 31, 2014	Apr. 30, 2014	Jan. 31, 2014	Oct. 31, 2013	Jul. 31, 2013	Apr. 30, 2015	Apr. 30, 2014	Apr. 30, 2013
Schedule Of Computation Of Basic And Diluted Earnings Per Common Share [Line Items]
Net loss from continuing operations		$ (8,825)	$ (4,123)	$ (9,908)	$ (10,308)	$ (12,233)	$ (8,393)	$ (14,574)	$ (17,646)	$ (33,164)	$ (52,846)	$ (47,503)
Net loss from discontinued operations, net of tax					(1,257)	(11,448)	430	420	278	(1,257)	(10,320)	(16,249)
Net loss applicable to common stockholders		$ (8,825)	$ (4,123)	$ (9,908)	$ (11,565)	$ (23,681)	$ (7,963)	$ (14,154)	$ (17,368)	$ (34,421)	$ (63,166)	$ (63,752)
Continuing operations										$ (0.42)	$ (0.70)	$ (0.69)
Discontinued operations										(0.02)	(0.14)	(0.23)
Basic and diluted loss per share										$ (0.44)	$ (0.84)	$ (0.92)
Basic and diluted weighted average number of shares outstanding										78,645	75,564	69,336
Outstanding stock options
Potentially dilutive securities (1):
Outstanding stock options	[1]									721	2,149	5,718
Restricted Stock
Potentially dilutive securities (1):
Outstanding stock options	[1]									427	293	67

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