Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2015	Apr. 30, 2014	Apr. 30, 2013
Statement of Comprehensive Income [Abstract]
Net loss	$ (34,421)	$ (63,166)	$ (63,752)
Other comprehensive gain (loss), net of tax:
Foreign currency translation adjustment	(934)	386	(96)
Unrealized gain (loss) on investments	(32)	88	(30)
Total other comprehensive gain (loss), net of tax	(966)	474	(126)
Comprehensive loss	$ (35,387)	$ (62,692)	$ (63,878)