Debt and Credit Facilities (Schedule of Long-Term Debt) (Details) (USD $) In Millions, unless otherwise specified	Apr. 30, 2015	Apr. 30, 2014	Feb. 25, 2013
Long - term debt
Total long term debt	$ 998us-gaap_LongTermDebt	$ 997us-gaap_LongTermDebt
Less current portion	250us-gaap_LongTermDebtCurrent	0us-gaap_LongTermDebtCurrent
Total Long term debt excluding current portion	748us-gaap_LongTermDebtNoncurrent	997us-gaap_LongTermDebtNoncurrent
5.0% notes due in fiscal 2014 [Member]
Long - term debt
Interest rate on long term debt (percent)			5.00%
2.5% notes, due in fiscal 2016 [Member]
Long - term debt
Total long term debt	250	249
Interest rate on long term debt (percent)	2.50%	2.50%
1.0% notes due in fiscal 2018 [Member]
Long - term debt
Total long term debt	249	249
Interest rate on long term debt (percent)	1.00%	1.00%
2.25% notes due in Fiscal 2023 [Member]
Long - term debt
Total long term debt	249	249
Interest rate on long term debt (percent)	2.25%	2.25%
3.75% notes due in Fiscal 2043 [Member]
Long - term debt
Total long term debt	$ 250	$ 250
Interest rate on long term debt (percent)	3.75%	3.75%

Contractual interest rate for funds borrowed, under the debt agreement.

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