Goodwill And Intangible Assets (Goodwill And Changes In Carrying Amount Of Goodwill By Operating Segment) (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2015	Dec. 31, 2014
Goodwill [Roll Forward]
Balance, beginning of period	$ 590.6	$ 559.0
Acquisitions of businesses	2.0	32.1
Currency translation and other adjustments	(1.6)	(0.5)
Balance, end of period	591.0	590.6
Global Specialty Engineered Materials [Member]
Goodwill [Roll Forward]
Balance, beginning of period	99.4	99.9
Acquisitions of businesses	0.0	0.0
Currency translation and other adjustments	(1.5)	(0.5)
Balance, end of period	97.9	99.4
Global Color, Additives And Inks [Member]
Goodwill [Roll Forward]
Balance, beginning of period	333.7	310.2
Acquisitions of businesses	2.0	23.5
Currency translation and other adjustments	(0.1)	0.0
Balance, end of period	335.6	333.7
Designed Structures and Solutions [Member]
Goodwill [Roll Forward]
Balance, beginning of period	144.7	136.3
Acquisitions of businesses	0.0	8.4
Currency translation and other adjustments	0.0	0.0
Balance, end of period	144.7	144.7
Performance Products And Solutions [Member]
Goodwill [Roll Forward]
Balance, beginning of period	11.2	11.0
Acquisitions of businesses	0.0	0.2
Currency translation and other adjustments	0.0	0.0
Balance, end of period	11.2	11.2
PolyOne Distribution [Member]
Goodwill [Roll Forward]
Balance, beginning of period	1.6	1.6
Acquisitions of businesses	0.0	0.0
Currency translation and other adjustments	0.0	0.0
Balance, end of period	$ 1.6	$ 1.6