Segment Information (Schedule of Segment Information) (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Segment Reporting Information [Line Items]
Sales	$ 901.6	$ 796.7
Operating Income	78.8	82.0
Assets	2,743.9		$ 2,705.3
Color, Additives and Inks
Segment Reporting Information [Line Items]
Sales	269.1	206.5
Specialty Engineered Materials
Segment Reporting Information [Line Items]
Sales	150.7	146.6
Performance Products and Solutions
Segment Reporting Information [Line Items]
Sales	170.6	162.2
PolyOne Distribution
Segment Reporting Information [Line Items]
Sales	311.2	281.4
Operating Segments \| Color, Additives and Inks
Segment Reporting Information [Line Items]
Sales	270.9	211.8
Operating Income	42.1	35.1
Assets	1,275.1		1,146.8
Operating Segments \| Specialty Engineered Materials
Segment Reporting Information [Line Items]
Sales	163.1	159.1
Operating Income	20.1	22.9
Assets	559.9		545.1
Operating Segments \| Performance Products and Solutions
Segment Reporting Information [Line Items]
Sales	191.0	183.7
Operating Income	22.7	22.1
Assets	291.0		275.8
Operating Segments \| PolyOne Distribution
Segment Reporting Information [Line Items]
Sales	315.5	286.1
Operating Income	18.2	18.6
Assets	260.0		250.9
Corporate and eliminations
Segment Reporting Information [Line Items]
Sales	(38.9)	(44.0)
Operating Income	(24.3)	$ (16.7)
Assets	$ 357.9		$ 486.7

Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

Reference 1: 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(a)(12))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 2: 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(11))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

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