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Restructuring and Other Reorganization-Related Charges (Reversals), net (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 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
Restructuring Cost and Reserve [Line Items]
Restructuring and other reorganization-related charges (reversals), net	$ 0.1us-gaap_RestructuringCharges	$ (0.1)us-gaap_RestructuringCharges	$ 0.7us-gaap_RestructuringCharges	$ (0.5)us-gaap_RestructuringCharges	$ 60.6us-gaap_RestructuringCharges	$ (0.2)us-gaap_RestructuringCharges	$ 0.3us-gaap_RestructuringCharges	$ (0.1)us-gaap_RestructuringCharges	$ 0.2us-gaap_RestructuringCharges	$ 60.6us-gaap_RestructuringCharges	$ (1.2)us-gaap_RestructuringCharges
Severance and termination costs
Restructuring Cost and Reserve [Line Items]
Restructuring and other reorganization-related charges (reversals), net									0.1	55.9	0
Payments for Restructuring									41.8
Restructuring Reserve, Translation Adjustment									(0.4)
Restructuring Reserve	4.4				46.5				4.4	46.5
Lease termination costs
Restructuring Cost and Reserve [Line Items]
Restructuring and other reorganization-related charges (reversals), net									0.1	4.2	(1.1)
Payments for Restructuring									1.2
Restructuring Reserve, Translation Adjustment									(0.1)
Restructuring Reserve	2.6				3.9				2.6	3.9
Other exit costs
Restructuring Cost and Reserve [Line Items]
Restructuring and other reorganization-related charges (reversals), net									0	0.5	(0.1)
Payments for Restructuring									0.5
Restructuring Reserve, Translation Adjustment									0
Restructuring Reserve	0				0.5				0	0.5
IAN
Restructuring Cost and Reserve [Line Items]
Restructuring and other reorganization-related charges (reversals), net										0.3
CMG
Restructuring Cost and Reserve [Line Items]
Restructuring and other reorganization-related charges (reversals), net										(0.2)
2013 Restructuring Plan [Domain]
Restructuring Cost and Reserve [Line Items]
Restructuring and other reorganization-related charges (reversals), net									0.1	61.2
Payments for Restructuring									43.5
Restructuring Reserve, Translation Adjustment									(0.5)
Restructuring Reserve	7.0				50.9				7.0	50.9
2013 Restructuring Plan [Domain] \| Severance and termination costs
Restructuring Cost and Reserve [Line Items]
Restructuring and other reorganization-related charges (reversals), net										55.9
2013 Restructuring Plan [Domain] \| Lease termination costs
Restructuring Cost and Reserve [Line Items]
Restructuring and other reorganization-related charges (reversals), net									0	4.8
2013 Restructuring Plan [Domain] \| Other exit costs
Restructuring Cost and Reserve [Line Items]
Restructuring and other reorganization-related charges (reversals), net										0.5
Prior Restructuring Plan [Domain]
Restructuring Cost and Reserve [Line Items]
Restructuring and other reorganization-related charges (reversals), net									0.1	(0.6)	(1.2)
Restructuring Reserve	$ 1.1								$ 1.1