Computations of Loss per Share Applicable to Common Stockholders (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Apr. 30, 2014	Jan. 31, 2014	Oct. 31, 2013	Jul. 31, 2013	Apr. 30, 2013	Jan. 31, 2013	Oct. 31, 2012	Jul. 31, 2012	Apr. 30, 2014		Apr. 30, 2013		Apr. 30, 2012
Schedule Of Computation Of Basic And Diluted Earnings Per Common Share [Line Items]
Net loss from continuing operations	$ (12,233)	$ (8,393)	$ (14,574)	$ (17,646)	$ (23,020)	$ (9,807)	$ (9,020)	$ (5,656)	$ (52,846)		$ (47,503)		$ (24,329)
Less accretion of redeemable convertible preferred stock													(38)
Net loss applicable to common stockholders									$ (52,846)		$ (47,503)		$ (24,367)
Net loss per share applicable to common stockholders, basic and diluted									$ (0.70)		$ (0.69)		$ (0.92)
Weighted average number of shares outstanding, basic and diluted									75,564		69,336		26,403
Outstanding stock options
Potentially dilutive securities:
Potentially dilutive securities									2,149	[1]	5,718	[1]	6,241	[1]
Redeemable Convertible Preferred Stock
Potentially dilutive securities:
Potentially dilutive securities													22,714	[1]
Restricted Stock
Potentially dilutive securities:
Potentially dilutive securities									293	[1]	67	[1]	1	[1]

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