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

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
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-Topic 835
-SubTopic 30
-Section 45
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-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

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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))
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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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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
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-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
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- Definition

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt, classified as current. 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
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-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19,20)
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- Definition

Amount after unamortized (discount) premium and debt issuance costs of long-term debt classified as noncurrent and excluding amounts to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Debt (Details) € in Millions, £ in Millions, $ in Millions	6 Months Ended	12 Months Ended
Debt (Details) € in Millions, £ in Millions, $ in Millions	Oct. 31, 2017 EUR (€)	Apr. 30, 2017 EUR (€)	Oct. 31, 2017 GBP (£)	Oct. 31, 2017 USD ($)	Apr. 30, 2017 GBP (£)	Apr. 30, 2017 USD ($)
Debt Instrument [Line Items]
Long-term debt, including current portion				$ 1,969		$ 1,938
Current portion of long-term debt				250		249
Long-term debt				1,719		1,689
1.00% notes, due January 15, 2018 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount				$ 250		$ 250
Debt Instrument, Maturity Date	Jan. 15, 2018	Jan. 15, 2018
Debt Instrument, Interest Rate, Stated Percentage	1.00%	1.00%	1.00%	1.00%	1.00%	1.00%
Long-term debt, including current portion				$ 250		$ 249
2.25% notes, due January 15, 2023 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount				$ 250		$ 250
Debt Instrument, Maturity Date	Jan. 15, 2023	Jan. 15, 2023
Debt Instrument, Interest Rate, Stated Percentage	2.25%	2.25%	2.25%	2.25%	2.25%	2.25%
Long-term debt, including current portion				$ 248		$ 248
1.20% notes, due July 7, 2026 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount \| €	€ 300	€ 300
Debt Instrument, Maturity Date	Jul. 07, 2026	Jul. 07, 2026
Debt Instrument, Interest Rate, Stated Percentage	1.20%	1.20%	1.20%	1.20%	1.20%	1.20%
Long-term debt, including current portion				$ 346		$ 324
2.60% notes, due July 7, 2028 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount \| £			£ 300		£ 300
Debt Instrument, Maturity Date	Jul. 07, 2028	Jul. 07, 2028
Debt Instrument, Interest Rate, Stated Percentage	2.60%	2.60%	2.60%	2.60%	2.60%	2.60%
Long-term debt, including current portion				$ 391		$ 383
3.75% notes, due January 15, 2043 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount				$ 250		$ 250
Debt Instrument, Maturity Date	Jan. 15, 2043	Jan. 15, 2043
Debt Instrument, Interest Rate, Stated Percentage	3.75%	3.75%	3.75%	3.75%	3.75%	3.75%
Long-term debt, including current portion				$ 248		$ 248
4.50% notes, due July 15, 2045 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount				$ 500		$ 500
Debt Instrument, Maturity Date	Jul. 15, 2045	Jul. 15, 2045
Debt Instrument, Interest Rate, Stated Percentage	4.50%	4.50%	4.50%	4.50%	4.50%	4.50%
Long-term debt, including current portion				$ 486		$ 486