Represents the interest coverage ratio required to be maintained under the financial covenant.

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Debt instrument floor interest rate.

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No definition available.

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Debt instrument maturity year.

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Maximum amount available under credit facility to issue letters of credit.

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No definition available.

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Number of tranches.

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No definition available.

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Percentage of reduction in interest rate on senior notes.

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No definition available.

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The expiration, mandatory redemption, or due date, month and year (YYYY-MM), of the financial instrument issued in exchange for the original debt being converted in a noncash (or part noncash) transaction. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or cash payments in the period.

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Percentage points added to the reference rate to compute the variable rate on the debt instrument.

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No definition available.

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Description of minimum financial levels (for example, tangible net worth and working capital) and achievement of certain financial ratios (for example, working capital ratio and debt service coverage ratio), and adherence to certain clauses which generally require or restrict certain actions (for example, entering into a debt arrangement with equal or greater seniority, and selling or discontinuing a certain business segment or material subsidiary) to be in compliance with the covenant clauses of the debt agreement. May also include a discussion of the adverse consequences that would result if the entity violates or fails to satisfy the covenants.

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Date the debt agreement requires the first payment to be made, in CCYY-MM-DD format.

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The reference rate for the variable rate of the debt instrument, such as LIBOR or the US Treasury rate and the maturity of the reference rate used, such as three months or six months LIBOR.

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No definition available.

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

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Description of the frequency of periodic payments (monthly, quarterly, annual).

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Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

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Incremental percentage increase (decrease) in the stated rate on a debt instrument.

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No definition available.

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

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Description of the interest rate as being fixed or variable, and, if variable, identification of the index or rate on which the interest rate is based and the number of points or percentage added to that index or rate to set the rate, and other pertinent information, such as frequency of rate resets.

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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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No definition available.

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

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Weighted average interest rate of debt outstanding.

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No definition available.

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The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

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No definition available.

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Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

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Including the current and noncurrent portions, aggregate carrying value as of the balance sheet date of loans payable (with maturities initially due after one year or beyond the operating cycle if longer).

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The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

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No definition available.

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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 - Additional Information (Details) € in Millions	6 Months Ended	12 Months Ended
Debt - Additional Information (Details) € in Millions	Jun. 30, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 EUR (€) tranche	Dec. 31, 2015 USD ($)
Debt Instrument [Line Items]
Debt instrument, covenant terms	In accordance with the terms of the Facility, we are required to maintain a minimum interest coverage ratio of 3.50 (based on the ratio of EBITDA, as defined in the Credit Agreement, to interest expense) and may not exceed a maximum leverage ratio of 3.50 (based on the ratio of total debt to EBITDA) throughout the term of the Facility.
Borrowings	$ 930,100,000	$ 805,600,000
Term loan
Debt Instrument [Line Items]
Face value \| €			€ 60
Debt instrument, interest rate terms	The loan has two tranches of which the first tranche for €25 million has a rate of Euribor +1.2% and a final maturity date of June 30, 2023, and a second tranche for €35 million has a rate of Euribor +1.25% with a final maturity date of June 30, 2024. The loans are payable in annual installments that began on June 30, 2017, for the first tranche, and beginning on June 30, 2019, for the second. There is a zero percent floor on the Euribor.
Number of tranches \| tranche			2
Debt instrument, payment terms	annual
Term loan \| Euribor
Debt Instrument [Line Items]
Debt instrument, floor rate			0.00%
Level 2 \| Term loan
Debt Instrument [Line Items]
Outstanding amount under loan	$ 61,600,000
Maximum
Debt Instrument [Line Items]
Interest coverage ratio required to be maintained	350.00%
3.95% senior unsecured notes due 2027
Debt Instrument [Line Items]
Face value		$ 400,000,000
Debt instrument, interest rate	3.95%	3.95%
Debt instrument, maturity year		2027
Increase in senior notes interest rate		0.25%
Effective interest rate	3.88%
3.95% senior unsecured notes due 2027 \| Level 2
Debt Instrument [Line Items]
Fair value of senior notes	$ 390,100,000
3.95% senior unsecured notes due 2027 \| Maximum
Debt Instrument [Line Items]
Debt instrument, interest rate		5.95%
3.95% senior unsecured notes due 2027 \| Treasury Lock \| Interest Lock Agreement
Debt Instrument [Line Items]
Percentage of effective interest rate benefit	0.25%
4.7% senior unsecured notes due 2025
Debt Instrument [Line Items]
Face value				$ 300,000,000
Debt instrument, interest rate				4.70%
Debt instrument, maturity year				2025
Increase in senior notes interest rate				0.25%
Effective interest rate	4.84%
4.7% senior unsecured notes due 2025 \| Level 2
Debt Instrument [Line Items]
Fair value of senior notes	$ 306,100,000
4.7% senior unsecured notes due 2025 \| Maximum
Debt Instrument [Line Items]
Debt instrument, interest rate				6.70%
Senior unsecured credit facility- revolving loan due 2021
Debt Instrument [Line Items]
Debt instrument expiration period	2021-06
Variable interest rate basis	LIBOR + 1.25%.
Spread on variable interest rate basis	1.25%
Debt instrument, interest rate terms	The interest rate ranges from LIBOR + 0.875% to a maximum of LIBOR + 1.875%, depending upon the Company’s leverage ratio.
Maximum amount available under credit facility to issue letters of credit	$ 40,000,000
Letters of credit outstanding under credit facility	0
Undrawn availability under credit facility	$ 515,000,000
Weighted average interest rate	3.17%
Senior unsecured credit facility- revolving loan due 2021 \| Level 2
Debt Instrument [Line Items]
Borrowings	$ 185,000,000
Senior unsecured credit facility- revolving loan due 2021 \| Maximum
Debt Instrument [Line Items]
Face value	$ 700,000,000
Variable interest rate basis	LIBOR + 1.875%
Spread on variable interest rate basis	1.875%
Senior unsecured credit facility- revolving loan due 2021 \| Minimum
Debt Instrument [Line Items]
Variable interest rate basis	LIBOR + 0.875
Spread on variable interest rate basis	0.875%
Tranche one \| Term loan
Debt Instrument [Line Items]
Face value \| €			€ 25
Variable interest rate basis	Euribor +1.2%
Spread on variable interest rate basis			1.20%
Debt instrument, maturity date	Jun. 30, 2023
Beginning date of first required loan payment	Jun. 30, 2017
Tranche two \| Term loan
Debt Instrument [Line Items]
Face value \| €			€ 35
Variable interest rate basis	Euribor +1.25%
Spread on variable interest rate basis			1.25%
Debt instrument, maturity date	Jun. 30, 2024
Beginning date of first required loan payment	Jun. 30, 2019