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Long-Term Debt - Long-Term Debt (Parenthetical) (Detail)	12 Months Ended
	Dec. 31, 2017	Jul. 03, 2014
2.56% due 2020, floating interest rate at Libor + 1.199% [Member]
Debt Instrument [Line Items]
Long-term debt maturity date	2020
Interest rate	2.56%
Description of floating rate basis	Libor + 1.199%
Basis spread on floating rate	1.199%
2.56% due 2020, floating interest rate at Libor + 1.056% [Member]
Debt Instrument [Line Items]
Long-term debt maturity date	2020
Interest rate	2.56%
Description of floating rate basis	Libor + 1.056%
Basis spread on floating rate	1.056%
0.59% due 2020, floating interest rate at Euribor + 0.917% [Member]
Debt Instrument [Line Items]
Long-term debt maturity date	2020
Interest rate	0.59%
Description of floating rate basis	Euribor + 0.917%
Basis spread on floating rate	0.917%
2.09% due 2021, floating interest rate at Libor + 0.525% [Member]
Debt Instrument [Line Items]
Long-term debt maturity date	2021
Interest rate	2.09%
Description of floating rate basis	Libor + 0.525%
Basis spread on floating rate	0.525%
2.22% due 2021, floating interest rate at Libor + 0.572% [Member]
Debt Instrument [Line Items]
Long-term debt maturity date	2021
Interest rate	2.22%
Description of floating rate basis	Libor + 0.572%
Basis spread on floating rate	0.572%
Zero Coupon due 2019 (Tranche A) [Member]
Debt Instrument [Line Items]
Interest rate		1.00%
Zero Coupon due 2019 (Tranche A) [Member] | Senior Unsecured Convertible Bonds [Member]
Debt Instrument [Line Items]
Long-term debt maturity date	2019
Interest rate	0.00%	0.00%
1.0% due 2021 (Tranche B) [Member]
Debt Instrument [Line Items]
Interest rate		1.00%
1.0% due 2021 (Tranche B) [Member] | Senior Unsecured Convertible Bonds [Member]
Debt Instrument [Line Items]
Long-term debt maturity date	2021
Interest rate	1.00%	1.00%
Zero-coupon, due 2022 (Tranche A) [Member] | Senior Unsecured Convertible Bonds [Member]
Debt Instrument [Line Items]
Long-term debt maturity date	2022
Interest rate	0.00%
0.25%, due 2024 (Tranche B) [Member]
Debt Instrument [Line Items]
Interest rate	0.25%
0.25%, due 2024 (Tranche B) [Member] | Senior Unsecured Convertible Bonds [Member]
Debt Instrument [Line Items]
Long-term debt maturity date	2024
Interest rate	0.25%
0.31% (weighted average), due 2018-2023, fixed interest rate [Member]
Debt Instrument [Line Items]
Interest rate	0.31%
0.31% (weighted average), due 2018-2023, fixed interest rate [Member] | Minimum [Member]
Debt Instrument [Line Items]
Long-term debt maturity date	2018
0.31% (weighted average), due 2018-2023, fixed interest rate [Member] | Maximum [Member]
Debt Instrument [Line Items]
Long-term debt maturity date	2023
1.95% (weighted average), due 2017, fixed interest rate [Member]
Debt Instrument [Line Items]
Long-term debt maturity date	2017
Interest rate	1.95%
0.41% (weighted average), due 2018, fixed interest rate [Member]
Debt Instrument [Line Items]
Long-term debt maturity date	2018
Interest rate	0.41%
0.87% (weighted average), due 2020, fixed interest rate [Member]
Debt Instrument [Line Items]
Long-term debt maturity date	2020
Interest rate	0.87%

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Debt Instrument Maturity Year

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- Definition

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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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