Debt and Financing Arrangements (Tables)

12 Months Ended

Apr. 30, 2012

Debt and Financing Arrangements [Abstract]

Long-term debt

	Year Ended April 30,
	2012		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		397,906		380,039
3.50% Notes due October 15, 2021		748,637		—
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	$	2,070,543	$	1,304,039
Current portion of long-term debt		50,000		—
Total long-term debt, less current portion	$	2,020,543	$	1,304,039