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.