Income Taxes (Deferred Tax Liabilities Not Recognized) (Details) - USD ($) $ in Millions	Apr. 30, 2016	Apr. 30, 2015
Income Tax Disclosure [Abstract]
Undistributed earnings of foreign subsidiaries	$ 1,005	$ 803
Deferred Tax Liability Not Recognized, Amount of Unrecognized Deferred Tax Liability, Undistributed Earnings of Foreign Subsidiaries	$ 222	$ 163