Condensed Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Oct. 31, 2015	Oct. 31, 2014	Oct. 31, 2015	Oct. 31, 2014
Statement of Comprehensive Income [Abstract]
Net loss	$ (4,852)	$ (9,908)	$ (15,096)	$ (21,473)
Other comprehensive gain (loss), net of tax:
Foreign currency translation adjustment	(103)	(456)	(73)	(458)
Unrealized gain (loss) on investments	(29)	(29)	1	18
Total other comprehensive loss, net of tax	(132)	(485)	(72)	(440)
Comprehensive loss	$ (4,984)	$ (10,393)	$ (15,168)	$ (21,913)