Goodwill and Intangible Assets (Goodwill and Changes in Carrying Amount of Goodwill by Operating Segment) (Details) $ in Millions	6 Months Ended
	Jun. 30, 2016 USD ($)
Goodwill [Roll Forward]
Balance, beginning of period	$ 597.7
Acquisitions of businesses	37.8
Currency translation and other adjustments	0.5
Balance, end of period	636.0
Specialty Engineered Materials
Goodwill [Roll Forward]
Balance, beginning of period	98.0
Acquisitions of businesses	37.8
Currency translation and other adjustments	0.6
Balance, end of period	136.4
Color, Additives and Inks
Goodwill [Roll Forward]
Balance, beginning of period	342.2
Acquisitions of businesses	0.0
Currency translation and other adjustments	(0.1)
Balance, end of period	342.1
Designed Structures and Solutions
Goodwill [Roll Forward]
Balance, beginning of period	144.7
Acquisitions of businesses	0.0
Currency translation and other adjustments	0.0
Balance, end of period	144.7
Performance Products and Solutions
Goodwill [Roll Forward]
Balance, beginning of period	11.2
Acquisitions of businesses	0.0
Currency translation and other adjustments	0.0
Balance, end of period	11.2
PolyOne Distribution
Goodwill [Roll Forward]
Balance, beginning of period	1.6
Acquisitions of businesses	0.0
Currency translation and other adjustments	0.0
Balance, end of period	$ 1.6