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Variable Interest Entities - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($) Investment	Dec. 31, 2016 USD ($) Investment	Dec. 31, 2015 USD ($)
Variable Interest Entity [Line Items]
Number of investments in VIEs | Investment	2	3
Proceeds from sale of equity method investments	$ (9.3)	$ 0.0	$ 0.0
Chaspark
Variable Interest Entity [Line Items]
Proceeds from sale of equity method investments	$ (9.3)

X

- Definition

Number Of Investments In Variable Interest Entities

+ References

No definition available.

+ Details

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X

- Definition

The cash inflow associated with the sale of equity method investments, which are investments in joint ventures and entities in which the entity has an equity ownership interest normally of 20 to 50 percent and exercises significant influence.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 12
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3179-108585

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X

- 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.

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- Details

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