Condensed Consolidated Statement of Changes in Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common stock	Treasury stock	Additional paid-in capital	Accumulated other comprehensive income (loss)	Accumulated deficit
Cumulative Effect of New Accounting Principle in Period of Adoption				$ 326		$ (326)
Beginning balance, Shares at Apr. 30, 2017		84,488	(200)
Beginning balance at Apr. 30, 2017	$ 186,305	$ 8	$ 0	455,755	$ (1,682)	(267,776)
Stock-based expense	9,649			9,649
Vested restricted stock units converted to shares, shares		21
Issuance of common stock upon exercise of stock options, shares		126
Issuance of common stock upon exercise of stock options	462			462
Vested restricted stock units converted to shares		1,535
Tax withholdings related to net share settlements of stock-based compensation awards, shares		(174)
Tax withholdings related to net share settlements of stock-based compensation awards	(825)			(825)
Shares issued under employee stock purchase plans, shares		257
Shares issued under employee stock purchase plans	938			938
Change in foreign currency translation adjustment	292				292
Change in unrealized gain on investments	21				21
Net loss	(2,371)					(2,371)
Ending balance, Shares at Oct. 31, 2017		86,253	(200)
Ending balance at Oct. 31, 2017	$ 194,471	$ 8	$ 0	$ 466,305	$ (1,369)	$ (270,473)