Fair Value (Details) (USD $) In Millions, unless otherwise specified															9 Months Ended
	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2013 Carrying Amount	Dec. 31, 2012 Carrying Amount	Sep. 30, 2013 Fair Value	Dec. 31, 2012 Fair Value	Sep. 30, 2013 Fair Value, Measurements, Recurring [Member] Level 1	Dec. 31, 2012 Fair Value, Measurements, Recurring [Member] Level 1	Sep. 30, 2013 Fair Value, Measurements, Recurring [Member] Level 2	Dec. 31, 2012 Fair Value, Measurements, Recurring [Member] Level 2	Sep. 30, 2013 Fair Value, Measurements, Recurring [Member] Level 3	Dec. 31, 2012 Fair Value, Measurements, Recurring [Member] Level 3	Sep. 30, 2013 Fair Value, Measurements, Recurring [Member] Total	Dec. 31, 2012 Fair Value, Measurements, Recurring [Member] Total	Sep. 30, 2013 Contingent Purchase Price Obligations [Member]
Assets:
Cash and cash equivalents			$ 1,521.5	$ 2,678.3	$ 1,521.5	$ 2,678.3	$ 1,521.5	$ 2,678.3					$ 1,521.5	$ 2,678.3
Short-term investments	12.9	20.6	12.9	20.6	12.9	20.6	12.9	20.6					12.9	20.6
Forward foreign exchange contracts			1.3	0.5	1.3	0.5			1.3	0.5			1.3	0.5
Available-for-sale securities			4.6	3.9	4.6	3.9	4.6	3.9					4.6	3.9
Cost method investments			21.7	23.1	21.7	23.1
Liabilities:
Short-term borrowings			18.3	6.4	18.3	6.4
Forward foreign exchange contracts			0.3	0	0.3	0			0.3				0.3
Contingent interest derivative			2.8	0	2.8	0			2.8				2.8
Contingent purchase price obligations			213.3	266.2	213.3	266.2					213.3	266.2	213.3	266.2
Debt			4,035.7	4,448.9	4,250.7	4,857.3
Changes in contingent purchase price obligations, payments															$ 68.9