Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended	12 Months Ended
	Jan. 31, 2018	Jan. 31, 2018	Apr. 30, 2019
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent		30.40%
Income Taxes (Textual) [Abstract]
Effective tax rate		28.50%
Expected tax rate		26.10%
Effective Income Tax Rate Reconciliation, Tax Cuts and Jobs Act, Amount	$ (20)
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)
Scenario, Forecast [Member]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent			21.00%