Condensed Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended
	Jul. 31, 2015	Jul. 31, 2014
Statement of Comprehensive Income [Abstract]
Net loss	$ (10,244)	$ (11,565)
Other comprehensive gain (loss), net of tax:
Foreign currency translation adjustment	30	(2)
Unrealized gain on investments	30	47
Total other comprehensive gain, net of tax	60	45
Comprehensive loss	$ (10,184)	$ (11,520)