Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Jul. 31, 2017	Jul. 31, 2016	Jul. 31, 2015
Income Tax [Line Items]
Unrecognized tax benefits that, if recognized, would affect the company's income tax rate	$ 8,477	$ 8,886	$ 8,764
Accrued interest and penalties	1,209	1,547
Total amount of interest and penalties benefit recognized	218	$ 231	$ 2,552
Expected decrease in unrecognized tax benefits due to resolution of uncertain tax positions	3,950
Expected decrease in interest due to resolution of uncertain tax positions	500
State and Local Jurisdiction
Income Tax [Line Items]
Tax credit carry forward	1,882
Gross state tax Net Operating Loss carry forwards	8,973
Deferred tax asset, Net Operating Loss carry forwards	$ 422
State and Local Jurisdiction | Earliest Tax Year
Income Tax [Line Items]
Tax credit carry forward expiration year	2026
Gross state tax Net Operating Loss carry forwards, expiration year	2018
State and Local Jurisdiction | Latest Tax Year
Income Tax [Line Items]
Tax credit carry forward expiration year	2027
Gross state tax Net Operating Loss carry forwards, expiration year	2037