Acquisitions (Pro Forma Information Of Consolidated Results Of Operations) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Apr. 30, 2012	Apr. 30, 2011
Acquisitions [Abstract]
Total revenues	$ 7,021,256	$ 5,790,215
Net earnings	$ 117,727	$ 99,138
Earnings per common share, Basic	$ 3.09	$ 2.34
Earnings per common share, Diluted	$ 3.07	$ 2.33