Net Income (Loss) Per Common Share (Details Textual)	3 Months Ended	9 Months Ended	3 Months Ended	9 Months Ended
	Apr. 30, 2012	Apr. 30, 2012	Apr. 30, 2011 Class A Nonvoting Common Stock [Member]	Apr. 30, 2011 Class A Nonvoting Common Stock [Member]
Net Income Per Common Share (Textual) [Abstract]
Common stock of Class A shares excluded from computations of diluted net income per share			2,500,000	3,100,000
Number of additional shares included in computation of diluted net loss per common share	3,182,000	4,419,000