Stockholders' Equity - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jan. 31, 2017	Jan. 31, 2016	Jan. 31, 2017	Jan. 31, 2016
Stock Based Compensation And Stockholders Equity [Line Items]
Stock-based compensation expense	$ 3,154	$ 2,400	$ 5,892	$ 4,679
Withholding taxes payable			$ 4,572	$ 2,484
Regular dividend declared and paid per common share	$ 0.33	$ 0.30	$ 0.66	$ 0.60
Dividends declared and paid			$ 34,704
Restricted Stock Units (RSUs)
Stock Based Compensation And Stockholders Equity [Line Items]
Withholding taxes payable			$ 4,572	$ 2,484