Income Taxes (Textual) (Details) - USD ($) $ in Millions	12 Months Ended
	Apr. 30, 2019	Apr. 30, 2018	Apr. 30, 2017	Apr. 30, 2016	Apr. 30, 2015	Apr. 30, 2014
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent		30.40%	35.00%	35.00%
Effective Income Tax Rate Reconciliation, Tax Cuts and Jobs Act, Amount		$ (19)
Tax Cuts and Jobs Act, Incomplete Accounting, Provisional Income Tax Expense (Benefit)		43
Tax Cuts and Jobs Act, Incomplete Accounting, Transition Tax for Accumulated Foreign Earnings, Provisional Income Tax Expense		91
Tax Cuts and Jobs Act, Incomplete Accounting, Change in Tax Rate, Provisional Income Tax Expense (Benefit)		(48)
Deferred Income, Tax Benefit of Intercompany Transfer of Assets, Before Amortization						$ 95
Other Income Tax Expense (Benefit), Continuing Operations		16	$ 16	$ 16	$ 15	$ 5
Deferred Tax Assets, Valuation Allowance		29	30
Gross unrecognized tax benefits		11	$ 9	$ 9	$ 13
Reduction in effective income tax rate if recognized		9
Estimated increase in unrecognized tax benefits in next 12 months as a result of net tax positions taken		0
Deferred Income, Tax Benefit of Intercompany Transfer of Assets, Net of Amortization		$ 27
Scenario, Forecast [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%