Goodwill - Changes to Carrying Value by Segment (Details) $ in Millions	6 Months Ended
Jun. 30, 2016 USD ($)
Changes in carrying amounts of goodwill
December 31, 2015	$ 431.3
Foreign currency translation	0.3
June 30, 2016	431.6
Operating segment \| Region One
Changes in carrying amounts of goodwill
December 31, 2015	337.5
Foreign currency translation	0.3
June 30, 2016	337.8
Operating segment \| Region Two
Changes in carrying amounts of goodwill
December 31, 2015	62.7
Foreign currency translation	0.0
June 30, 2016	62.7
Operating segment \| Region Three
Changes in carrying amounts of goodwill
December 31, 2015	31.1
Foreign currency translation	0.0
June 30, 2016	$ 31.1

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6388280&loc=d3e13770-109266

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

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- Definition

Amount of increase (decrease) from foreign currency translation adjustments of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

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