Acquisitions (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2012		Jun. 30, 2011
Business Combinations
Number of Businesses Acquired	6		9
Business Acquisition, Goodwill Amount	$ 79.0		$ 22.0
Business Acquisition, Cost of Investment	86.1	[1]	86.2	[1]
Cash Acquired from Acquisition	(8.6)		(2.4)
Business Acquisition, Cash Paid	89.3		86.4
Acquisition related payments	34.5		47.6
Acquisitions, including deferred payments, net of cash acquired	51.6		38.6
Current Year Acquisition
Business Combinations
Business Acquisition, Cost of Investment	59.3		8.1
Prior Year Acquisition
Business Combinations
Business Acquisition, Cost of Investment	35.4		80.5
Business Combination, Operating expense	$ 3.2	[2]	$ 0.2	[2]
IAN
Business Combinations
Number of Businesses Acquired	3		9
CMG
Business Combinations
Number of Businesses Acquired	3

[1] Of the total cash paid, $34.5 and $47.6 for the six months ended June 30, 2012 and 2011, respectively, are classified under the financing section of the unaudited Consolidated Statements of Cash Flows within acquisition-related payments. These amounts relate to increases in our ownership interests in our consolidated subsidiaries, as well as deferred payments for acquisitions that closed on or after January 1, 2009. Of the total cash paid, $51.6 and $38.6 for the six months ended June 30, 2012 and 2011, respectively, are classified under the investing section of the unaudited Consolidated Statements of Cash Flows within acquisitions, including deferred payments, net of cash acquired. These amounts relate to initial payments for new transactions and deferred payments for acquisitions that closed prior to January 1, 2009.

[2] Represents cash payments made that were either in excess of the contractual value or contingent upon the future employment of the former owners of acquired companies.