Derivative Financial Instruments (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Jul. 31, 2013	Jul. 31, 2012
Cash Flow Hedging [Member] | Currency derivatives [Member]
Derivative instrument gains and losses affecting statements of operations
Net gain (loss) recognized in AOCI	$ 10	$ 13
Net Sales [Member] | Cash Flow Hedging [Member] | Currency derivatives [Member]
Derivative instrument gains and losses affecting statements of operations
Net gain (loss) reclassified from AOCI into income	1	1
Net Sales [Member] | Not designated as hedges [Member] | Currency derivatives [Member]
Derivative instrument gains and losses affecting statements of operations
Gain (loss) on derivative instruments recognized in income	4	2
Other Income [Member] | Not designated as hedges [Member] | Currency derivatives [Member]
Derivative instrument gains and losses affecting statements of operations
Gain (loss) on derivative instruments recognized in income	3	(4)
Cost of Sales [Member] | Not designated as hedges [Member] | Commodity derivatives [Member]
Derivative instrument gains and losses affecting statements of operations
Gain (loss) on derivative instruments recognized in income	$ 0	$ 4