Derivative Financial Instruments (Gain (Loss) on Derivatives Recognized in Consolidated Statement of Operations) (Details) - USD ($) $ in Millions	12 Months Ended
Apr. 30, 2016	Apr. 30, 2015
Cash Flow Hedging [Member] \| Treasury Lock [Member]
Fair values of derivative instruments affecting statements of operations
Net gain (loss) recognized in AOCI	$ 8	$ 0
Designated as Hedging Instrument [Member] \| Cash Flow Hedging [Member] \| Currency derivatives [Member]
Fair values of derivative instruments affecting statements of operations
Net gain (loss) recognized in AOCI	22	96
Designated as Hedging Instrument [Member] \| 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 earnings	60	41
Not Designated as Hedging Instrument [Member] \| Net Sales [Member] \| Currency derivatives [Member]
Fair values of derivative instruments affecting statements of operations
Net gain (loss) recognized in earnings	1	26
Not Designated as Hedging Instrument [Member] \| Other Income [Member] \| Currency derivatives [Member]
Fair values of derivative instruments affecting statements of operations
Net gain (loss) recognized in earnings	$ (5)	$ 4

Schedule of Derivative Instruments Gain Loss in Statement of Financial Performance.

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- Definition

Amount of increase (decrease) in the fair value of derivatives recognized in the income statement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4A
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=56946850&loc=SL5618551-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-Subparagraph (a),(c),(d),(e)
-URI http://asc.fasb.org/extlink&oid=56946850&loc=SL5624171-113959

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- Definition

The effective portion of net gain (loss) reclassified from accumulated other comprehensive income into income on derivative instruments designated and qualifying as hedging instruments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=56946850&loc=SL5624171-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4D
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=56946850&loc=SL5624177-113959

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- Definition

The effective portion of gains and losses (net) on derivative instruments designated and qualifying as hedging instruments that was recognized in other comprehensive income during the current period.

+ References

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