Income Taxes (Deferred Tax Liabilities Not Recognized) (Details) (USD $) In Millions, unless otherwise specified	Apr. 30, 2015	Apr. 30, 2014
Income Tax Disclosure [Abstract]
Undistributed earnings of foreign subsidiaries	$ 803	$ 797
Deferred Tax Liability Not Recognized, Amount of Unrecognized Deferred Tax Liability, Undistributed Earnings of Foreign Subsidiaries	$ 163	$ 175