Condensed Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended
	Jul. 31, 2017	Jul. 31, 2016
Statement of Comprehensive Income [Abstract]
Net loss	$ (2,316)	$ (5,105)
Other comprehensive gain (loss), net of tax:
Foreign currency translation adjustment	283	(638)
Unrealized loss on investments	(14)	(1)
Total other comprehensive gain (loss), net of tax	269	(639)
Comprehensive loss	$ (2,047)	$ (5,744)