Derivative Financial Instruments (Fair Value of Derivatives in a Gain (Loss) Position) (Details) (Currency derivatives [Member], USD $) In Millions, unless otherwise specified	Apr. 30, 2014	Apr. 30, 2013
Fair value of derivatives in a gain position [Member] | Cash Flow Hedging [Member] | Other Assets [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] | Cash Flow Hedging [Member] | Other Current Assets [Member]
Fair values of derivative instruments
Fair value of derivatives in a gain (loss) position	6	6
Fair value of derivatives in a gain position [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] | 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] | Not designated as hedges [Member] | Other Current Assets [Member]
Fair values of derivative instruments
Fair value of derivatives in a gain (loss) position	5
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	0
Fair value of derivatives in a loss position [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] | Cash Flow Hedging [Member] | Other Current 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] | Cash Flow Hedging [Member] | Accrued expenses [Member]
Fair values of derivative instruments
Fair value of derivatives in a gain (loss) position	(6)	(5)
Fair value of derivatives in a loss position [Member] | Cash Flow Hedging [Member] | Other Liabilities [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] | Other Current 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] | Not designated as hedges [Member] | Accrued expenses [Member]
Fair values of derivative instruments
Fair value of derivatives in a gain (loss) position	$ 0	$ (1)