Business Combinations (Purchase Price Allocation) (Details) (USD $) In Millions, except Share data, unless otherwise specified	9 Months Ended		0 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Mar. 13, 2013 Spartech [Member]
Business Acquisition [Line Items]
Spartech shares outstanding			31,200,000
Spartech restricted stock units			200,000
Spartech shares converted			31,400,000
Exchange ratio			0.3167
PolyOne shares issued			10,000,000
PolyOne closing stock price on March 13, 2013			$ 25.05
Total value of PolyOne shares issued		$ 253.8	$ 249.9
Cash consideration transferred to Spartech Shareholders			83.4
Fair value of Spartech equity awards, net of deferred tax benefits (1)			2.4
Total consideration transferred to Spartech equity holders			335.7
Revolving credit facilities repaid at close	20.9	117.5	77.2
Spartech senior notes repaid at close (including make-whole provisions and interest payable)			102.3
Total consideration transferred to debt and equity holders			515.2
Cash acquired			(4.1)
Total consideration transferred to debt and equity holders, net of cash acquired	$ 0	$ 259.4	$ 511.1