Derivative Financial Instruments (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Jan. 31, 2014	Jan. 31, 2013	Jan. 31, 2014	Jan. 31, 2013
Cash Flow Hedging [Member] | Currency derivatives [Member]
Derivative instrument gains and losses affecting statements of operations
Net gain (loss) recognized in AOCI	$ 10	$ (4)	$ 5	$ (6)
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)	0	(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	5	(1)	4	(2)
Interest Expense [Member] | Fair Value Hedging [Member] | Interest rate swaps [Member]
Derivative instrument gains and losses affecting statements of operations
Gain (loss) on derivative instruments recognized in income			0	1
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	2	1	4	(1)
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