Income Taxes (Textual) (Details) - USD ($) $ in Millions	12 Months Ended
	Apr. 30, 2017	Apr. 30, 2016	Apr. 30, 2015	Apr. 30, 2014	May 01, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred Income, Tax Benefit of Intercompany Transfer of Assets, Before Amortization				$ 95
Other Income Tax Expense (Benefit), Continuing Operations	$ 16	$ 16	$ 15	5
Deferred Tax Assets, Valuation Allowance	30	25
Gross unrecognized tax benefits	9	9	$ 13	$ 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 13)	$ 43	$ 59
Scenario, Forecast [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets					$ 27