Derivative Financial Instruments and Hedging Activities (Details 1) - Currency derivatives [Member] - USD ($) $ in Millions	Jul. 31, 2017	Apr. 30, 2017
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	$ 7	$ 2
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	4	0
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	8	21
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	2	9
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	5	2
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	3	1
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	(1)
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)	(1)
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	(7)	(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	(1)	(4)
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	(17)	(8)
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	$ (22)	$ (4)