Stockholders' Equity - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended			6 Months Ended
	Jan. 31, 2016	Oct. 31, 2015	Jan. 31, 2015	Jan. 31, 2016	Jan. 31, 2015
Stock Based Compensation And Stockholders Equity [Line Items]
Stock-based compensation expense	$ 2,400		$ 1,762	$ 4,679	$ 3,327
Withholding taxes payable				$ 2,484	$ 1,562
Regular dividends declared and paid per common share	$ 0.30	$ 0.30	$ 0.27	$ 0.60	$ 0.54
Regular Dividends declared and paid				$ 31,485
Restricted Stock
Stock Based Compensation And Stockholders Equity [Line Items]
Withholding taxes payable				$ 2,484	$ 1,562