Debt - Summary of Senior Unsecured Credit Facility (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2018	Dec. 31, 2017
Capital Lease Obligations
Debt	$ 267,424	$ 606,548
Deferred financing costs	$ 19,553
Standard & Poor's, BBB Rating
Capital Lease Obligations
Debt instrument, credit rating	BBB
Moody's, Baa2 Rating
Capital Lease Obligations
Debt instrument, credit rating	Baa2
Unsecured revolving credit facility
Capital Lease Obligations
Debt	$ 267,424	216,775
Unsecured revolving credit facility \| USD
Capital Lease Obligations
Maturity Date	Feb. 22, 2021
Debt	$ 245,000	105,000
Unsecured revolving credit facility \| USD \| LIBOR
Capital Lease Obligations
Variable interest rate (percentage)	1.00%
Unsecured revolving credit facility \| EUR
Capital Lease Obligations
Maturity Date	Feb. 22, 2021
Debt	$ 22,424	111,775
Unsecured revolving credit facility \| EUR \| EURIBOR
Capital Lease Obligations
Variable interest rate (percentage)	1.00%
Term Loan
Capital Lease Obligations
Debt	$ 0	389,773
Unamortized discount		1,200
Deferred financing costs		200
Term Loan \| EUR
Capital Lease Obligations
Debt	0	283,425
Delayed Draw term loan
Capital Lease Obligations
Debt	$ 0	$ 106,348

Sum of the carrying values as of the balance sheet date of all debt, including all short-term borrowings, long-term debt, and capital lease obligations.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.13,16)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.16)
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

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- References

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- Definition

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

+ References

No definition available.

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- Definition

Description of the credit rating indicative of likelihood of repayment of the debt instrument given by a credit rating agency (for example, Standard and Poor's, Moody's, Fitch).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21475-112644

Reference 2: 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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- 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 accumulated amortization, of debt discount.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28541-108399

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- Definition

Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 30
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-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28555-108399

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