Condensed Consolidated Statements Of Operations (Parenthetical) (USD $)	3 Months Ended
	Jul. 31, 2011		Jul. 31, 2010
Diluted	$ 0.09	[1]	$ 0.05	[1]
Class B
Diluted	$ 0.09		$ 0.05

[1] (a) Basic per share amounts are the same for Class A and Class B shares. Diluted per share amounts for Class A shares are shown above. Diluted earnings per share for Class B shares under the two-class method are $0.09 and $0.05 for the periods ended July 31, 2011 and 2010, respectively. See Note E to the Condensed Consolidated Financial Statements.