Derivative Financial Instruments and Hedging Activities (Details 1) - Currency derivatives [Member] - USD ($) $ in Millions	Jul. 31, 2018	Apr. 30, 2018
Fair value of derivatives in a gain position [Member] | Not designated as hedges [Member] | Other Current Assets [Member]
Fair values of derivative instruments
Fair value of derivatives in a gain (loss) position	$ 1	$ 0
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	5	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	7	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	4	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	1	2
Fair value of derivatives in a loss position [Member] | Not designated as hedges [Member] | Other Current Assets [Member]
Fair values of derivative instruments
Fair value of derivatives in a gain (loss) position	0	0
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	(1)	(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	(5)	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	(9)	(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	$ (2)	$ (18)