Derivative Financial Instruments (Details 1) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Apr. 30, 2012	Apr. 30, 2011
Cash Flow Hedging [Member] | Currency derivatives [Member]
Fair values of derivative instruments affecting statements of operations
Net gain (loss) recognized in AOCI	$ 9	$ (27)
Net Investment Hedging [Member] | Currency derivatives [Member]
Fair values of derivative instruments affecting statements of operations
Net gain (loss) recognized in AOCI		(1)
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	(8)
Net Sales [Member] | Not designated as hedges [Member] | Currency derivatives [Member]
Fair values of derivative instruments affecting statements of operations
Gain (loss) on derivative instruments recognized in income	9	(10)
Cost of Sales [Member] | Not designated as hedges [Member] | Commodity derivatives [Member]
Fair values of derivative instruments affecting statements of operations
Gain (loss) on derivative instruments recognized in income	(3)	10
Other Income [Member] | Fair Value Hedging [Member] | Interest rate swaps [Member]
Fair values of derivative instruments affecting statements of operations
Gain (loss) on derivative instruments recognized in income	(1)	2
Other Income [Member] | Not designated as hedges [Member] | Currency derivatives [Member]
Fair values of derivative instruments affecting statements of operations
Gain (loss) on derivative instruments recognized in income	(2)	(2)
Interest Expense [Member] | Fair Value Hedging [Member] | Interest rate swaps [Member]
Fair values of derivative instruments affecting statements of operations
Gain (loss) on derivative instruments recognized in income	$ 3	$ 3