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
-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

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- Definition

Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-Subparagraph (a)
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Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=77997519&loc=d3e13476-108611

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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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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.

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Debt - Fair Value of Debt Outstanding (Details)	Dec. 31, 2017 EUR (€)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 EUR (€)	Dec. 31, 2016 USD ($)	Sep. 30, 2016	Jun. 30, 2015 EUR (€)
7.456% Senior Notes Due 2018
Debt Instrument [Line Items]
Senior notes, interest rate	7.456%	7.456%	7.456%	7.456%
Senior unsecured notes principal amount		$ 500,000,000
5.95% Senior Notes Due 2020
Debt Instrument [Line Items]
Senior notes, interest rate	5.95%	5.95%	5.95%	5.95%	5.95%
Senior unsecured notes principal amount		$ 750,000,000
2.5% Senior Notes Due 2022
Debt Instrument [Line Items]
Senior notes, interest rate	2.50%	2.50%	2.50%	2.50%	2.50%	2.50%
Fair value of senior notes \| €	€ 690,000,000		€ 682,000,000
Senior unsecured notes principal amount \| €	€ 650,000,000		€ 650,000,000			€ 650,000,000
4.5% Senior Notes Due 2024
Debt Instrument [Line Items]
Senior notes, interest rate	4.50%	4.50%	4.50%	4.50%	4.50%
Senior unsecured notes principal amount		$ 500,000,000
5.0% Senior Notes Due 2026
Debt Instrument [Line Items]
Senior notes, interest rate	5.00%	5.00%	5.00%	5.00%	5.00%
Senior unsecured notes principal amount		$ 750,000,000
3.8% Senior Notes Due 2028
Debt Instrument [Line Items]
Senior notes, interest rate	3.80%	3.80%	3.80%	3.80%
Senior unsecured notes principal amount		$ 1,000,000,000
Level 2 \| 7.456% Senior Notes Due 2018
Debt Instrument [Line Items]
Senior notes, interest rate	7.456%	7.456%	7.456%	7.456%
Fair value of senior notes		$ 516,000,000		$ 541,000,000
Level 2 \| 5.95% Senior Notes Due 2020
Debt Instrument [Line Items]
Senior notes, interest rate	5.95%	5.95%	5.95%	5.95%
Fair value of senior notes		$ 810,000,000		$ 823,000,000
Level 2 \| 2.5% Senior Notes Due 2022
Debt Instrument [Line Items]
Senior notes, interest rate	2.50%	2.50%	2.50%	2.50%
Fair value of senior notes		$ 828,000,000		$ 718,000,000
Senior unsecured notes principal amount \| €	€ 650,000,000		€ 650,000,000
Level 2 \| 4.5% Senior Notes Due 2024
Debt Instrument [Line Items]
Senior notes, interest rate	4.50%	4.50%	4.50%	4.50%
Fair value of senior notes		$ 528,000,000		$ 511,000,000
Level 2 \| 5.0% Senior Notes Due 2026
Debt Instrument [Line Items]
Senior notes, interest rate	5.00%	5.00%	5.00%	5.00%
Fair value of senior notes		$ 807,000,000		$ 782,000,000
Level 2 \| 3.8% Senior Notes Due 2028
Debt Instrument [Line Items]
Senior notes, interest rate	3.80%	3.80%	3.80%	3.80%
Fair value of senior notes		$ 969,000,000		$ 0