Debt and Credit Facilities (Schedule of Long-Term Debt) (Details) (USD $) In Millions, unless otherwise specified	Apr. 30, 2014	Apr. 30, 2013	Feb. 25, 2013 5.0% notes due in fiscal 2014 [Member]	Apr. 30, 2014 2.5% notes, due in fiscal 2016 [Member]	Apr. 30, 2013 2.5% notes, due in fiscal 2016 [Member]	Apr. 30, 2014 1.0% notes due in fiscal 2018 [Member]	Apr. 30, 2013 1.0% notes due in fiscal 2018 [Member]	Apr. 30, 2014 2.25% notes due in Fiscal 2023 [Member]	Apr. 30, 2013 2.25% notes due in Fiscal 2023 [Member]	Apr. 30, 2014 3.75% notes due in Fiscal 2043 [Member]	Apr. 30, 2013 3.75% notes due in Fiscal 2043 [Member]	Apr. 30, 2014 Other long-term debt [Member]	Apr. 30, 2013 Other long-term debt [Member]
Long - term debt
Total long term debt	$ 997	$ 999		$ 249	$ 249	$ 249	$ 249	$ 249	$ 249	$ 250	$ 250	$ 0	$ 2
Less current portion	0	2
Total Long term debt excluding current portion	$ 997	$ 997
Interest rate on long term debt (percent)			5.00%	2.50%	2.50%	1.00%	1.00%	2.25%	2.25%	3.75%	3.75%