Computation of Basic and Diluted Net Income Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended		6 Months Ended
		Jan. 31, 2017	Jan. 31, 2016	Jan. 31, 2017	Jan. 31, 2016
Earnings Per Share [Abstract]
Net income (loss)		$ 7,510	$ (2,985)	$ 10,046	$ (1,609)
Weighted-average number of common shares outstanding-basic		12,466	12,418	12,442	12,422
Effect of dilutive securities:
Stock options and restricted stock units		214		270
Weighted-average number of common shares outstanding-diluted		12,680	12,418	12,712	12,422
Basic net income (loss) per share		$ 0.60	$ (0.24)	$ 0.81	$ (0.13)
Diluted net income (loss) per share		$ 0.59	$ (0.24)	$ 0.79	$ (0.13)
Anti-dilutive shares related to outstanding stock options and unvested restricted stock	[1]	372	326	372	357

[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.