Debt and Financing Arrangements (Tables)

3 Months Ended

Jul. 31, 2011

Debt and Financing Arrangements (Tables) [Abstract]

Long-term debt

	July 31, 2011		April 30, 2011
4.78% Senior Notes due June 1, 2014	$	100,000	$	100,000
6.12% Senior Notes due November 1, 2015		24,000		24,000
6.63% Senior Notes due November 1, 2018		394,489		380,039
5.55% Senior Notes due April 1, 2022		400,000		400,000
4.50% Senior Notes due June 1, 2025		400,000		400,000
Total long-term debt	$	1,318,489	$	1,304,039