Net Income per Common Share - Additional Informations (Detail) (Class A nonvoting common stock) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jan. 31, 2015	Jan. 31, 2014	Jan. 31, 2015	Jan. 31, 2014
Class A nonvoting common stock
Earnings Per Share [Line Items]
Common stock of Class A shares excluded from computations of diluted net income per share	3,860	2,537	3,878	2,521