Condensed Consolidated Statement of Changes in Stockholders' Equity - 6 months ended Oct. 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, 2016		82,270	(200)
Beginning balance at Apr. 30, 2016	$ 184,534	$ 8	$ 0	$ 437,239	$ (878)	$ (251,835)
Excess tax deficiency related to stock-based expense	(43)			(43)
Stock-based expense	8,430			8,430
Issuance of restricted stock awards		91
Exercise of stock options and vested restricted stock units, shares		978
Exercise of stock options and vested restricted stock units	(188)			(188)
Shares issued under employee stock plans, shares		324
Shares issued under employee stock plans	905			905
Change in foreign currency translation adjustment	(1,126)				(1,126)
Change in unrealized gain on investments	(2)				(2)
Net loss	(9,239)					(9,239)
Ending balance, Shares at Oct. 31, 2016		83,663	(200)
Ending balance at Oct. 31, 2016	$ 183,271	$ 8	$ 0	$ 446,343	$ (2,006)	$ (261,074)