Long-Term Debt (Components Of Long-Term Debt) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended		12 Months Ended		12 Months Ended			12 Months Ended
	Apr. 30, 2013	Apr. 30, 2012	Apr. 30, 2013 Senior Notes, 5.500%, Due November 2022	Oct. 25, 2012 Senior Notes, 5.500%, Due November 2022	Apr. 30, 2013 Senior Notes, 7.875%, Due January 2013	Nov. 26, 2012 Senior Notes, 7.875%, Due January 2013	Apr. 30, 2012 Senior Notes, 7.875%, Due January 2013	Apr. 30, 2013 Senior Notes, 5.125%, Due October 2014	Apr. 30, 2012 Senior Notes, 5.125%, Due October 2014
Debt Instrument [Line Items]
Senior Notes	$ 497,330	$ 0			$ 0		$ 599,913	$ 399,648	$ 399,412
Acquisition obligation, due June 2012	0	30,831
Capital lease obligations	9,702	10,393
Total long term debt	906,680	1,040,549		500,000		600,000
Less: Current portion	(722)	(631,434)
Long-term debt	$ 905,958	$ 409,115
Senior Notes, interest rate			5.50%		7.875%			5.125%
Senior Notes, maturity date	Jun. 01, 2012		Nov. 01, 2022		Jan. 15, 2013			Oct. 30, 2014