Derivative Financial Instruments (Details 1) (Currency derivatives [Member], USD $) In Millions, unless otherwise specified	Jul. 31, 2013	Apr. 30, 2013
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	$ 15	$ 6
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	5	2
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
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
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	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		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	(5)	(3)
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	(1)	0
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		(4)
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		(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		$ (1)