Condensed Consolidated Statements of Changes in Stockholders' Equity - 9 months ended Jan. 31, 2016 - USD ($) shares in Thousands, $ in Thousands	Total	Common stock	Treasury stock	Additional paid-in capital	Accumulated other comprehensive income (loss)	Accumulated deficit
Beginning balance, Shares at Apr. 30, 2015		80,346	(200)
Beginning balance at Apr. 30, 2015	$ 191,383	$ 8	$ 0	$ 418,509	$ (638)	$ (226,496)
Stock-based expense	11,850			11,850
Issuance of restricted stock awards, Shares		242
Exercise of stock options and vested restricted stock units, Shares		789
Exercise of stock options and vested restricted stock units	895			895
Shares issued under employee stock plans, shares		297
Shares issued under employee stock plans	1,298			1,298
Change in foreign currency translation adjustment	(526)				(526)
Change in unrealized gain on investments	(33)				(33)
Net loss applicable to common stockholders	(18,210)					(18,210)
Ending balance, Shares at Jan. 31, 2016		81,674	(200)
Ending balance at Jan. 31, 2016	$ 186,657	$ 8	$ 0	$ 432,552	$ (1,197)	$ (244,706)