Derivative Financial Instruments (Fair Value of Derivatives in a Gain (Loss) Position) (Details) (USD $) In Millions, unless otherwise specified	Apr. 30, 2013	Apr. 30, 2012
Fair value of derivatives in a gain position [Member] | Currency derivatives [Member] | Cash Flow Hedging [Member] | Other Assets [Member]
Fair values of derivative instruments
Fair value of derivatives in a gain (loss) position	$ 2	$ 1
Fair value of derivatives in a gain position [Member] | Currency derivatives [Member] | Cash Flow Hedging [Member] | Other Current Assets [Member]
Fair values of derivative instruments
Fair value of derivatives in a gain (loss) position	6
Fair value of derivatives in a gain position [Member] | Currency derivatives [Member] | Cash Flow Hedging [Member] | Accrued expenses [Member]
Fair values of derivative instruments
Fair value of derivatives in a gain (loss) position	2	2
Fair value of derivatives in a gain position [Member] | Currency derivatives [Member] | Cash Flow Hedging [Member] | Other Liabilities [Member]
Fair values of derivative instruments
Fair value of derivatives in a gain (loss) position	0	0
Fair value of derivatives in a gain position [Member] | Currency derivatives [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] | Interest rate swaps [Member] | Fair Value Hedging [Member] | Other Assets [Member]
Fair values of derivative instruments
Fair value of derivatives in a gain (loss) position		2
Fair value of derivatives in a gain position [Member] | Commodity derivatives [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 loss position [Member] | Currency derivatives [Member] | Cash Flow Hedging [Member] | Other 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] | Currency derivatives [Member] | Cash Flow Hedging [Member] | Other Current Assets [Member]
Fair values of derivative instruments
Fair value of derivatives in a gain (loss) position	(2)
Fair value of derivatives in a loss position [Member] | Currency derivatives [Member] | Cash Flow Hedging [Member] | Accrued expenses [Member]
Fair values of derivative instruments
Fair value of derivatives in a gain (loss) position	(5)	(7)
Fair value of derivatives in a loss position [Member] | Currency derivatives [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] | Currency derivatives [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] | Interest rate swaps [Member] | Fair Value Hedging [Member] | Other Assets [Member]
Fair values of derivative instruments
Fair value of derivatives in a gain (loss) position		0
Fair value of derivatives in a loss position [Member] | Commodity derivatives [Member] | Not designated as hedges [Member] | Accrued expenses [Member]
Fair values of derivative instruments
Fair value of derivatives in a gain (loss) position		$ (1)