Condensed Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Oct. 31, 2016	Oct. 31, 2015	Oct. 31, 2016	Oct. 31, 2015
Statement of Comprehensive Income [Abstract]
Net loss	$ (4,134)	$ (4,852)	$ (9,239)	$ (15,096)
Other comprehensive gain (loss), net of tax:
Foreign currency translation adjustment	(488)	(103)	(1,126)	(73)
Unrealized gain (loss) on investments	(1)	(29)	(2)	1
Total other comprehensive gain (loss), net of tax	(489)	(132)	(1,128)	(72)
Comprehensive loss	$ (4,623)	$ (4,984)	$ (10,367)	$ (15,168)