Consolidated Statements of Shareholders' Equity (Unaudited) - USD ($) shares in Thousands, $ in Millions		Total		Total PolyOne shareholders' equity		Common Shares	Common Shares Held in Treasury	Additional Paid-in Capital	Retained Earnings		Accumulated Other Comprehensive (Loss) Income	Non-controlling Interests
Beginning balance at Dec. 31, 2018		$ 540.6		$ 540.0		$ 1.2	$ (1,018.7)	$ 1,166.9	$ 472.9		$ (82.3)	$ 0.6
Beginning balance (in shares) at Dec. 31, 2018						122,200
Beginning balance, Treasury shares (in shares) at Dec. 31, 2018							(44,500)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		38.3		38.2					38.2			0.1
Other comprehensive gain (loss)		3.2		3.2							3.2
Cash dividends declared	[1]	(14.8)		(14.8)					(14.8)
Share-based compensation and exercise of awards		1.6		1.6			$ 1.1	0.5
Share-based compensation and exercise of awards (in shares)							100
Ending balance at Mar. 31, 2019		568.9		568.2		$ 1.2	$ (1,017.6)	1,167.4	496.3		(79.1)	0.7
Ending balance (in shares) at Mar. 31, 2019						122,200
Ending balance, Treasury shares (in shares) at Mar. 31, 2019							(44,400)
Beginning balance at Dec. 31, 2019		1,052.7		1,051.9		$ 1.2	$ (1,043.1)	1,175.2	1,001.2		(82.6)	0.8
Beginning balance (in shares) at Dec. 31, 2019						122,200
Beginning balance, Treasury shares (in shares) at Dec. 31, 2019							(45,300)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		32.8		32.8					32.8			0.0
Other comprehensive gain (loss)		(10.7)		(10.7)							(10.7)
Noncontrolling interest activity		(0.8)										(0.8)
Cash dividends declared		(18.7)	[2]	(18.7)	[2]				(18.7)	[1]
Repurchase of common shares		(13.6)		(13.6)			$ (13.6)
Repurchase of common shares (in shares)							(1,000)
Common shares equity offering		496.1		496.1		$ 0.2	$ 161.3	334.6
Common shares equity offering (in shares)							15,300
Share-based compensation and exercise of awards		1.1		1.1			$ 1.6	(0.5)
Share-based compensation and exercise of awards (in shares)							200
Ending balance at Mar. 31, 2020		$ 1,538.6		$ 1,538.6		$ 1.4	$ (893.8)	$ 1,509.3	$ 1,015.0		$ (93.3)	$ 0.0
Ending balance (in shares) at Mar. 31, 2020						122,200
Ending balance, Treasury shares (in shares) at Mar. 31, 2020							(30,800)

[1] ⁽¹⁾ Dividends declared per share were $0.1950 for the period ending March 31, 2019.

[2] ⁽¹⁾ Dividends declared per share were $0.2025 for the period ended March 31, 2020.