Debt Issuances and Repayments [Abstract]

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- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

+ Details

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- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: 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(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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- Definition

Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

+ References

Reference 1: 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(a)(2))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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- Definition

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.

+ References

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

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Debt (Details Textual) € in Millions, £ in Millions, $ in Millions	9 Months Ended	12 Months Ended
	Jan. 31, 2017 EUR (€)	Apr. 30, 2016 EUR (€)	Jan. 31, 2017 GBP (£)	Jan. 31, 2017 USD ($)	Apr. 30, 2016 GBP (£)	Apr. 30, 2016 USD ($)
Debt Issuances and Repayments [Abstract]
Long-term Debt				$ 1,918		$ 1,230
1.20% notes, due July 7, 2026 [Member]
Debt Issuances and Repayments [Abstract]
Debt Instrument, Face Amount	€ 300	€ 0		$ 321
Debt Instrument, Interest Rate, Stated Percentage	1.20%	1.20%	1.20%	1.20%	1.20%	1.20%
Debt Instrument, Maturity Date	Jul. 07, 2026	Jul. 07, 2026
Long-term Debt				$ 318		$ 0
2.60% notes, due July 7, 2028 [Member]
Debt Issuances and Repayments [Abstract]
Debt Instrument, Face Amount			£ 300	$ 375	£ 0
Debt Instrument, Interest Rate, Stated Percentage	2.60%	2.60%	2.60%	2.60%	2.60%	2.60%
Debt Instrument, Maturity Date	Jul. 07, 2028	Jul. 07, 2028
Long-term Debt				$ 369		$ 0