Net Income per Common Share - Additional Informations (Detail) (Class A nonvoting common stock [Member])	3 Months Ended		6 Months Ended
	Jan. 31, 2014	Jan. 31, 2013	Jan. 31, 2014	Jan. 31, 2013
Class A nonvoting common stock [Member]
Earnings Per Share [Line Items]
Common stock of Class A shares excluded from computations of diluted net income per share	2,537,000	3,539,000	2,521,000	4,044,000