Segment Information Operations (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Segments:
Revenue	$ 1,543.0	$ 1,506.8
Segment operating income (loss)	(42.4)	(39.4)
Interest expense	(36.8)	(32.6)
Interest income	6.4	8.0
Other income (expense), net	1.8	(1.3)
Loss before income taxes	(71.0)	(65.3)
Depreciation and amortization of fixed assets and intangible assets	38.2	34.6
Capital expenditures	17.8	22.4
IAN
Segments:
Segment revenue	1,241.1	1,243.9
Segment operating income (loss)	(22.6)	(15.3)
Depreciation and amortization of fixed assets and intangible assets	30.9	28.4
Capital expenditures	10.0	12.8
CMG
Segments:
Segment revenue	301.9	262.9
Segment operating income (loss)	14.0	7.5
Depreciation and amortization of fixed assets and intangible assets	3.8	3.4
Capital expenditures	1.0	2.0
Corporate and other
Segments:
Segment operating income (loss)	(33.8)	(31.6)
Depreciation and amortization of fixed assets and intangible assets	3.5	2.8
Capital expenditures	$ 6.8	$ 7.6