Derivative Financial Instruments (Details) (Currency derivatives [Member], USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Oct. 31, 2014	Oct. 31, 2013	Oct. 31, 2014	Oct. 31, 2013
Cash Flow Hedging [Member]
Derivative instrument gains and losses affecting statements of operations
Net gain (loss) recognized in AOCI	$ 42	$ (15)	$ 47	$ (5)
Net Sales [Member] | Cash Flow Hedging [Member]
Derivative instrument gains and losses affecting statements of operations
Net gain (loss) reclassified from AOCI into income	6	0	4	1
Net Sales [Member] | Not designated as hedges [Member]
Derivative instrument gains and losses affecting statements of operations
Gain (loss) on derivative instruments recognized in income	11	(5)	8	(1)
Other Income [Member] | Not designated as hedges [Member]
Derivative instrument gains and losses affecting statements of operations
Gain (loss) on derivative instruments recognized in income	$ 3	$ 0	$ (6)	$ 2