Debt (Details Textual) € in Millions, £ in Millions, $ in Millions	Jul. 31, 2016 EUR (€)	Jul. 31, 2016 GBP (£)	Jul. 31, 2016 USD ($)	Apr. 30, 2016 USD ($)
One Point Two Percent Notes Due in Fiscal Two Thousand Twenty Seven [Member]
Debt Issuances and Repayments [Abstract]
Debt Instrument, Face Amount	€ 300		$ 335	$ 0
Debt Instrument, Interest Rate, Stated Percentage	1.20%	1.20%	1.20%	1.20%
Long-term Debt			$ 332	$ 0
Two Point Six Percent Notes Due in Fiscal Two Thousand Twenty Nine [Member]
Debt Issuances and Repayments [Abstract]
Debt Instrument, Face Amount		£ 300	$ 397	$ 0
Debt Instrument, Interest Rate, Stated Percentage	2.60%	2.60%	2.60%	2.60%
Long-term Debt			$ 391	$ 0

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Name:	us-gaap_LongTermDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant