Goodwill and Other Intangible Assets (Goodwill Rollforward) (Details) - USD ($) $ in Millions	12 Months Ended
	Apr. 30, 2016	Apr. 30, 2015
Amount recorded as goodwill
Goodwill , Beginning Balance	$ 607	$ 620
Goodwill, Written off Related to Sale of Business Unit	(16)
Foreign currency translation adjustment	(1)	(13)
Goodwill , Ending Balance	$ 590	$ 607