Income Taxes (Schedule of Components of Income Tax Expense (Benefit) for Continuing Operations) (Details) (USD $) In Thousands	12 Months Ended
	Apr. 30, 2011	Apr. 30, 2010	Apr. 30, 2009
Income Taxes
Federal, Current	$ 188,086	$ 92,992	$ 243,085
State, Current	45,068	23,625	38,418
Foreign, Current	21,456	16,052	1,393
Current income tax expense (benefit)	254,610	132,669	282,896
Federal, Deferred	(799)	128,900	36,739
State, Deferred	3,521	33,448	6,582
Foreign, Deferred	288	172	98
Deferred income tax expense (benefit)	3,010	162,520	43,419
Total income taxes for continuing operations	$ 257,620	$ 295,189	$ 326,315