Cash Paid for Acquisitions (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2014		Jun. 30, 2013
Business Combinations [Abstract]
Cost of investment: current year acquisitions	$ 63.7		$ 51.9
Cost of investment: prior-year acquisitions	9.0		27.8
Less: net cash acquired	(13.3)		(4.7)
Total cost of investment	59.4		75.0
Operating expense 1	0.1	[1]	0	[1]
Total cash paid for acquisitions	59.5	[2]	75.0	[2]
Acquisitions, including deferred payments, net of cash acquired	50.8		48.2
Acquisition-related payments	$ 8.6		$ 26.8

[1] 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.

[2] Of the total cash paid, $8.6 and $26.8 for the six months ended June 30, 2014, and 2013, 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, $50.8 and $48.2 for the six months ended June 30, 2014, and 2013, 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.