Computation of Basic and Diluted Net Income Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended		9 Months Ended
		Apr. 30, 2017	Apr. 30, 2016	Apr. 30, 2017	Apr. 30, 2016
Earnings Per Share [Abstract]
Net (loss) income		$ (59,664)	$ 4,970	$ (49,618)	$ 3,361
Weighted average number of common shares outstanding-basic		12,486	12,392	12,457	12,412
Effect of dilutive securities:
Stock options and restricted stock units			161		211
Weighted average number of common shares outstanding-diluted		12,486	12,553	12,457	12,623
Basic net (loss) income per share		$ (4.78)	$ 0.40	$ (3.98)	$ 0.27
Diluted net (loss) income per share		$ (4.78)	$ 0.40	$ (3.98)	$ 0.27
Anti-dilutive shares related to outstanding stock options and unvested restricted stock	[1]	242	87	228	5

[1] These shares related to outstanding stock options and unvested restricted stock were not included in our calculations of diluted earnings per share, as the effect of including them would be anti-dilutive.