Derivative Financial Instruments (Details 1) - Currency derivatives [Member] - USD ($) $ in Millions	Jul. 31, 2016	Apr. 30, 2016
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	$ 0	$ 1
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
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	25	23
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	14	3
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	10	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	3
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	(2)	(4)
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	(9)
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	(6)	(2)
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	(5)	(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	$ (2)	$ (9)

Fair value of derivatives in a gain position [Member] | Not designated as hedges [Member] | Other Current Assets [Member]

Fair value of derivatives in a gain position [Member] | Not designated as hedges [Member] | Accrued Expenses [Member]

Fair value of derivatives in a gain position [Member] | Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member] | Other Current Assets [Member]

Fair value of derivatives in a gain position [Member] | Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member] | Other Assets [Member]

Fair value of derivatives in a gain position [Member] | Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member] | Accrued Expenses [Member]

Fair value of derivatives in a gain position [Member] | Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member] | Other Liabilities [Member]

Fair value of derivatives in a loss position [Member] | Not designated as hedges [Member] | Other Current Assets [Member]

Fair value of derivatives in a loss position [Member] | Not designated as hedges [Member] | Accrued Expenses [Member]

Fair value of derivatives in a loss position [Member] | Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member] | Other Current Assets [Member]

Fair value of derivatives in a loss position [Member] | Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member] | Other Assets [Member]

Fair value of derivatives in a loss position [Member] | Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member] | Accrued Expenses [Member]

Fair value of derivatives in a loss position [Member] | Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member] | Other Liabilities [Member]