Cash Flows - Net Cash Paid for Acquisitions (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Additional Cash Flow Elements and Supplemental Cash Flow Information [Abstract]
Fair value of assets acquired	$ 0	$ 30.2	$ 411.4
Liabilities assumed or created	0	(5.1)	(127.5)
Net assets of businesses acquired	0	25.1	283.9
Other payments	2.6	5.8	0
Payment of contingent consideration	0	0	1.3
Net cash paid for acquisitions	$ 2.6	$ 30.9	$ 285.2