Debt - Credit Agreement (Details)	12 Months Ended
Dec. 31, 2018 USD ($)
Letter of Credit
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 30,000,000.0
Revolving Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 485,000,000
Revolving Credit Facility \| Eurodollar
Debt Instrument [Line Items]
Spread on variable rate	3.00%
Revolving Credit Facility \| Base Rate
Debt Instrument [Line Items]
Spread on variable rate	2.00%
Revolving Credit Facility \| Line of Credit
Debt Instrument [Line Items]
Unused capacity commitment fee percentage	0.50%
Revolving Credit Facility, U.S. Dollars
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 240,000,000
Revolving Credit Facility, Multi Currency
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 245,000,000

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

No definition available.

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- Definition

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.

+ Details

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- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

The fee, expressed as a percentage of the line of credit facility, for available but unused credit capacity under the credit facility.

+ References

No definition available.

+ Details

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- Details

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- Details

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- Details

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- Details

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- Details

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- Details

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- Details

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