Business Combination (Purchase Price Allocation (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended			0 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Mar. 13, 2013		Mar. 13, 2013
Business Acquisition [Line Items]
Spartech revolving credit facilities repaid at close	$ 122.8	$ 117.5	$ 0
Total consideration transferred to debt and equity holders, net of cash acquired	47.2	259.4	33.8
Spartech Corporation
Business Acquisition [Line Items]
Spartech shares outstanding				31,200,000		31,200,000
Spartech shares converted						31,400,000
Exchange ratio				31.67%
PolyOne shares issued				10,000,000		10,000,000
PolyOne closing stock price on March 13, 2013				$ 25.05		$ 25.05
Total value of PolyOne shares issued				249.9		249.9
Cash consideration transferred to shareholders						83.4
Fair value of Spartech equity awards, net of deferred tax benefits				2.4	[1]	2.4	[1]
Total consideration transferred to Spartech equity holders						335.7
Spartech revolving credit facilities repaid at close						77.2	[2]
Spartech senior notes repaid at close						102.3	[2]
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						$ 511.1
Spartech Corporation | Restricted stock units
Business Acquisition [Line Items]
Spartech restricted stock units						200,000

[1] In accordance with ASC 718, Compensation — Stock Compensation, the fair value of replacement awards attributable to pre-combination service is recognized as part of purchase consideration. The $2.4 million represents the fair value of Spartech replacement equity awards of $3.9 million net of deferred income tax benefits of $1.5 million. The fair value of awards attributable to post-combination service amounted to $2.7 million and are being recognized as stock compensation over their requisite service periods within PolyOne's Consolidated Statements of Income.

[2] In accordance with the provisions of Spartech's 7.08% senior notes due 2016 and revolving credit facilities, at the time of closing, PolyOne repaid all borrowings under Spartech's revolving credit facilities, which amounted to $77.2 million. Additionally, PolyOne repaid $102.3 million related to Spartech's 7.08% senior notes due 2016, including $88.9 million of aggregated principal, $10.3 million make-whole provisions, and $3.1 million of interest payable.