Acquisitions Cash Paid for Acquisitions (Details) - USD ($) $ in Millions		9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014
Cash Paid for Acquisitions [Abstract]
Cost of investment: current-year acquisitions		$ 8.3	$ 87.2
Cost of investment: prior-year acquisitions		31.8	13.3
Less: net cash acquired		(2.4)	(24.9)
Total cost of investment		37.7	75.6
Operating expense	[1]	17.6	1.8
Total cash paid for acquisitions	[2]	55.3	77.4
Payments for Previous Acquisitions		31.8	12.7
Current Year Acquisitions, Net of Cash Acquired		$ 5.9	$ 62.9

[1] Represents cash payments made that were either in excess of the initial value of contingent payments or contingent upon the future employment of the former owners of the acquired companies and are recorded in the operating section of the Consolidated Statements of Cash Flows.

[2] Of the total cash paid for acquisitions, $31.8 and $12.7 for the nine months ended September 30, 2015, and 2014, respectively, are classified under the financing section of the unaudited Consolidated Statements of Cash Flows as acquisition-related payments. These amounts relate to deferred payments and increases in our ownership interest for prior acquisitions. $5.9 and $62.9 for the nine months ended September 30, 2015, and 2014, respectively, are classified under the investing section of the unaudited Consolidated Statements of Cash Flows, as acquisitions, net of cash acquired. These amounts relate to initial payments for new transactions.