Debt and Financing Arrangements (Details Textual) (USD $)	3 Months Ended		6 Months Ended														12 Months Ended
	Oct. 31, 2013 Bank	Oct. 31, 2012	Oct. 31, 2013 Bank	Oct. 31, 2012	Sep. 05, 2013	Apr. 30, 2013	Oct. 31, 2013 Interest rate contracts - net [Member]	Oct. 31, 2013 4.78% Senior Notes due June 1, 2014 [Member]	Apr. 30, 2013 4.78% Senior Notes due June 1, 2014 [Member]	Oct. 31, 2013 6.12% Senior Notes due November 1, 2015 [Member]	Apr. 30, 2013 6.12% Senior Notes due November 1, 2015 [Member]	Oct. 31, 2013 6.63% Senior Notes due November 1, 2018 [Member]	Apr. 30, 2013 6.63% Senior Notes due November 1, 2018 [Member]	Oct. 31, 2013 3.50% Senior Notes due October 15, 2021 [Member]	Apr. 30, 2013 3.50% Senior Notes due October 15, 2021 [Member]	Oct. 18, 2011 3.50% Senior Notes due October 15, 2021 [Member]	Apr. 30, 2014 5.55% Senior Notes due April 1, 2022 [Member]	Oct. 31, 2013 5.55% Senior Notes due April 1, 2022 [Member]	Apr. 30, 2013 5.55% Senior Notes due April 1, 2022 [Member]	Jun. 01, 2020 4.50% Senior Notes due June 1, 2025 [Member]	Oct. 31, 2013 4.50% Senior Notes due June 1, 2025 [Member]	Apr. 30, 2013 4.50% Senior Notes due June 1, 2025 [Member]
Debt and Financing Arrangements (Textual) [Abstract]
Percentage of notes								4.78%	4.78%	6.12%	6.12%	6.63%	6.63%	3.50%	3.50%	3.50%		5.55%	5.55%		4.50%	4.50%
Payment of Senior Notes due in fiscal 2014																	$ 50,000,000
First period payment of Senior Notes																				100,000,000
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gain recognized on derivative instrument							17,200,000
Debt and Financing Arrangements (Additional Textual) [Abstract]
Number of banks	11		11
Revolving credit facility maximum borrowing capacity	1,500,000,000		1,500,000,000		1,000,000,000
Revolving credit facility, expiration date	Sep. 06, 2018
Percentage of the principal amount thereof which company can prepay	100.00%		100.00%
Interest paid	22,800,000	26,700,000	45,200,000	48,900,000
Outstanding balance under revolving credit facility	207,000,000		207,000,000			0
Revolving credit facility weighted-average interest rate	1.10%		1.10%
Notional amount	$ 750,000,000		$ 750,000,000