Income Taxes (Textual) (Details) - USD ($) $ in Millions	12 Months Ended
	Apr. 30, 2016	Apr. 30, 2015	Apr. 30, 2014	Apr. 30, 2013
Income Tax Disclosure [Abstract]
Deferred Income, Tax Benefit of Intercompany Transfer of Assets, Before Amortization			$ 95
Other Income Tax Expense (Benefit), Continuing Operations	$ 16	$ 15	5
Deferred Tax Assets, Valuation Allowance	25	27
Gross unrecognized tax benefits	9	13	$ 11	$ 11
Reduction in effective income tax rate if recognized	6
Estimated increase in unrecognized tax benefits in next 12 months as a result of net tax positions taken	0
Deferred benefit – tax (Note 11)	$ 59	$ 75