Derivative Financial Instruments (Gain (Loss) on Derivatives Recognized in Consolidated Statement of Operations) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Apr. 30, 2013	Apr. 30, 2012
Cash Flow Hedging [Member] | Currency derivatives [Member]
Fair values of derivative instruments affecting statements of operations
Net gain (loss) recognized in AOCI	$ 7	$ 9
Net Sales [Member] | Cash Flow Hedging [Member] | Currency derivatives [Member]
Fair values of derivative instruments affecting statements of operations
Net gain (loss) reclassified from AOCI into income	1	(8)
Net Sales [Member] | Not designated as hedges [Member] | Currency derivatives [Member]
Fair values of derivative instruments affecting statements of operations
Gain (loss) recognized in income	0	9
Other Income [Member] | Fair Value Hedging [Member] | Interest Rate Swap [Member]
Fair values of derivative instruments affecting statements of operations
Gain (loss) recognized in income	0	(1)
Other Income [Member] | Not designated as hedges [Member] | Currency derivatives [Member]
Fair values of derivative instruments affecting statements of operations
Gain (loss) recognized in income	(2)	(2)
Cost of Sales [Member] | Not designated as hedges [Member] | Commodity derivatives [Member]
Fair values of derivative instruments affecting statements of operations
Gain (loss) recognized in income	4	(3)
Interest Expense [Member] | Fair Value Hedging [Member] | Interest Rate Swap [Member]
Fair values of derivative instruments affecting statements of operations
Gain (loss) recognized in income	$ 2	$ 3