Derivative Financial Instruments and Hedging Activities (Details 1) - Currency derivatives [Member] - USD ($) $ in Millions	Oct. 31, 2018	Apr. 30, 2018
Fair value of derivatives in a gain position [Member] | Not designated as hedges [Member] | Accrued Expenses [Member]
Fair values of derivative instruments
Fair value of derivatives in a gain (loss) position	$ 0	$ 1
Fair value of derivatives in a gain position [Member] | Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member] | Other Current Assets [Member]
Fair values of derivative instruments
Fair value of derivatives in a gain (loss) position	18	2
Fair value of derivatives in a gain position [Member] | Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member] | Other Assets [Member]
Fair values of derivative instruments
Fair value of derivatives in a gain (loss) position	18	1
Fair value of derivatives in a gain position [Member] | Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member] | Accrued Expenses [Member]
Fair values of derivative instruments
Fair value of derivatives in a gain (loss) position	1	4
Fair value of derivatives in a gain position [Member] | Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member] | Other Liabilities [Member]
Fair values of derivative instruments
Fair value of derivatives in a gain (loss) position	0	2
Fair value of derivatives in a loss position [Member] | Not designated as hedges [Member] | Accrued Expenses [Member]
Fair values of derivative instruments
Fair value of derivatives in a gain (loss) position	(4)	(5)
Fair value of derivatives in a loss position [Member] | Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member] | Other Current Assets [Member]
Fair values of derivative instruments
Fair value of derivatives in a gain (loss) position	(3)	(2)
Fair value of derivatives in a loss position [Member] | Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member] | Other Assets [Member]
Fair values of derivative instruments
Fair value of derivatives in a gain (loss) position	(2)	0
Fair value of derivatives in a loss position [Member] | Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member] | Accrued Expenses [Member]
Fair values of derivative instruments
Fair value of derivatives in a gain (loss) position	(3)	(23)
Fair value of derivatives in a loss position [Member] | Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member] | Other Liabilities [Member]
Fair values of derivative instruments
Fair value of derivatives in a gain (loss) position	$ 0	$ (18)