Net Income per Common Share - Additional Informations (Detail)	12 Months Ended			9 Months Ended	12 Months Ended
	Jul. 31, 2013	Jul. 31, 2012	Jul. 31, 2011	Apr. 30, 2012 Class A nonvoting common stock [Member]	Jul. 31, 2013 Class A nonvoting common stock [Member]	Jul. 31, 2011 Class A nonvoting common stock [Member]
Earnings Per Share [Line Items]
Basic (in shares)	51,330,000	52,453,000	52,639,000
Common stock of Class A shares excluded from computations of diluted net income per share				4,592,486	3,760,098	3,049,611