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Stockholders' Equity - Additional Information (Detail) - USD ($)
$ / shares in Units, $ in Thousands
3 Months Ended
Oct. 31, 2015
Oct. 31, 2014
Stock Based Compensation And Stockholders Equity [Line Items]    
Stock-based compensation expense $ 2,279 $ 1,565
Regular dividends declared and paid per common share $ 0.30 $ 0.27
Regular Dividends declared and paid $ 15,743  
Restricted Stock    
Stock Based Compensation And Stockholders Equity [Line Items]    
Withholding taxes payable $ 2,484