Derivative Financial Instruments (Fair Value of Derivatives in a Gain (Loss) Position) (Details) - Currency derivatives [Member] - USD ($) $ in Millions	Apr. 30, 2016	Apr. 30, 2015
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	$ 3
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		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	(4)	(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		(7)
Cash Flow Hedging [Member] \| Fair value of derivatives in a gain position [Member] \| Designated as Hedging Instrument [Member] \| Other Assets [Member]
Fair values of derivative instruments
Fair value of derivatives in a gain (loss) position	3	20
Cash Flow Hedging [Member] \| Fair value of derivatives in a gain position [Member] \| Designated as Hedging Instrument [Member] \| Other Current Assets [Member]
Fair values of derivative instruments
Fair value of derivatives in a gain (loss) position	23	42
Cash Flow Hedging [Member] \| Fair value of derivatives in a gain position [Member] \| Designated as Hedging Instrument [Member] \| Accrued expenses [Member]
Fair values of derivative instruments
Fair value of derivatives in a gain (loss) position	4	0
Cash Flow Hedging [Member] \| Fair value of derivatives in a gain position [Member] \| Designated as Hedging Instrument [Member] \| Other Liabilities [Member]
Fair values of derivative instruments
Fair value of derivatives in a gain (loss) position	3	0
Cash Flow Hedging [Member] \| Fair value of derivatives in a loss position [Member] \| Designated as Hedging Instrument [Member] \| Other Assets [Member]
Fair values of derivative instruments
Fair value of derivatives in a gain (loss) position	(2)	(3)
Cash Flow Hedging [Member] \| Fair value of derivatives in a loss position [Member] \| Designated as Hedging Instrument [Member] \| Other Current Assets [Member]
Fair values of derivative instruments
Fair value of derivatives in a gain (loss) position	(2)	(2)
Cash Flow Hedging [Member] \| Fair value of derivatives in a loss position [Member] \| Designated as Hedging Instrument [Member] \| Accrued expenses [Member]
Fair values of derivative instruments
Fair value of derivatives in a gain (loss) position	(8)	(6)
Cash Flow Hedging [Member] \| Fair value of derivatives in a loss position [Member] \| Designated as Hedging Instrument [Member] \| Other Liabilities [Member]
Fair values of derivative instruments
Fair value of derivatives in a gain (loss) position	$ (9)	$ (6)

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

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

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

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

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

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

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

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