Business Combinations (Narrative) (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended																12 Months Ended			0 Months Ended						12 Months Ended	0 Months Ended
	Dec. 31, 2014		Sep. 30, 2014		Jun. 30, 2014		Mar. 31, 2014		Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Feb. 28, 2013	Dec. 01, 2014	Mar. 13, 2013		Mar. 13, 2013		Mar. 13, 2014	Dec. 19, 2012
Business Acquisition [Line Items]
Payments to Acquire Businesses, Net of Cash Acquired																	$ 47.2	$ 259.4	$ 33.8
Spartech revolving credit facilities repaid at close																	122.8	117.5	0
Acquisition costs related to this acquisition											1.2		4.9		8.7
Sales	869.3	[1]	958.4	[2]	1,005.5	[3]	1,002.3	[4]	923.6	[5]	1,008.9	[6]	1,037.6	[7]	801.1	[8]	3,835.5	3,771.2	2,860.8
Goodwill	590.6								559.0								590.6	559.0	405.5
Selling and administrative expense
Business Acquisition [Line Items]
Acquisition costs related to this acquisition																		7.6	3.9
Senior Notes | 5.250% senior notes due 2023
Business Acquisition [Line Items]
Debt Instrument, Interest Rate During Period																				5.25%
Stated interest rate	5.25%								5.25%								5.25%	5.25%
Accella [Member]
Business Acquisition [Line Items]
Payments to Acquire Businesses, Net of Cash Acquired																					47.2
Intangible Assets, Net (Including Goodwill)																					40.5
Spartech Corporation
Business Acquisition [Line Items]
Payments to Acquire Businesses, Net of Cash Acquired																								511.1
Revenue reported by acquired entity for last annual period																			1,149.4
Net income from continuing operations by acquired entity for last annual period																			2.7
Cash consideration transferred for each common share																						$ 2.67		$ 2.67
Exchange ratio																						31.67%
Cash consideration transferred to shareholders																								83.4
PolyOne shares issued																						10,000,000		10,000,000
Fair value of Spartech equity awards, net of deferred tax benefits																						2.4	[9]	2.4	[9]
Fair value Of equity awards before deferred tax benefits																								3.9
Deferred tax benefit																						1.5		1.5
Vested in period, total fair value																								2.7
Spartech revolving credit facilities repaid at close																								77.2	[10]
Spartech senior notes repaid at close																								102.3	[10]
Principal repayments of senior notes of business acquisition																								88.9
Make whole costs																								10.3
Interest payable																						3.1		3.1
Consideration transferred																								515.2
Cash acquired																								4.1
Goodwill																										162.6
Finalized purchase price allocation, Goodwill																										9.4
Spartech Corporation | Senior Notes | Senior Notes Due 2016
Business Acquisition [Line Items]
Stated interest rate																						7.08%		7.08%
Glasforms, Inc.
Business Acquisition [Line Items]
Sales																			51.1
Consideration transferred																											34.3
Cash acquired																											1.2
Goodwill																											12.4
Identifiable intangible assets																											$ 10.7

[1] Included for the fourth quarter 2014 are: 1) mark-to-market pension and other post-retirement charge of $56.5 million, 2) employee separation and restructuring costs of $23.2 million, 3) environmental remediation costs of $2.6 million and 5) a gain related to the reimbursement of previously incurred environmental costs of $2.1 million.

[2] Included for the third quarter 2014 are: 1) $17.9 million in employee separation and restructuring costs, 2) $5.9 million in environmental remediation costs and 3) a gain related to the reimbursement of previously incurred environmental costs of $1.6 million.

[3] Included for the second quarter 2014 are: 1) $35.1 million in employee separation and restructuring costs and 2) $5.4 million tax benefit associated with our investments in certain foreign affiliates.

[4] Included for the first quarter 2014 are: 1) $17.9 million in employee separation and restructuring costs.

[5] Included for the fourth quarter 2013 are: 1) gains from the SunBelt earn-out of $26.8 million, 2) mark-to-market pension and other post-retirement benefit gains of $44.0 million, 3) environmental remediation costs of $52.6 million, 4) a gain related to the reimbursement of previously incurred environmental costs of $3.4 million and 5) employee separation and restructuring costs of $28.3 million.

[6] Included for the third quarter 2013 are: 1) $5.3 million in environmental remediation costs, 2) $10.9 million in employee separation and restructuring costs, 3) $7.0 million gain on commercial litigation, 4) $5.2 million in debt extinguishment costs associated with our outstanding debt repurchases and 5) $1.2 million of acquisition and divestiture-related costs.

[7] Included for the second quarter 2013 are: 1) pre-tax gain of $223.7 million related to the sale of the Resin Business, 2) $2.9 million in employee separation and restructuring costs, 3) acquisition and divestiture-related costs of $4.9 million, 4) environmental remediation costs of $1.3 million and 5) a gain related to the reimbursement of previously incurred environmental costs of $14.9 million.

[8] Included for the first quarter 2013 are: 1) $9.9 million in employee separation and restructuring costs 2) acquisition and divestiture-related costs of $8.7 million, 3) environmental remediation costs of $2.0 million, 4) a gain related to the reimbursement of previously incurred environmental costs of $5.2 million and 5) $10.6 million in debt extinguishment costs related to the early retirement of our senior secured term loan.

[9] 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.

[10] 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.