Fair Value (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Assets:
Cash and cash equivalents	$ 2,442.2		$ 3,002.2
Short-term investments	43.6		20.6
Available-for-sale securities	4.0		4.3
Interest rate and foreign currency derivative instruments	0.5		0.2
Cost method investments	13.9		14.2
Liabilities:
Short-term debt	28.6		28.7
Interest rate and foreign currency derivative instruments	49.9		48.9
Contingent purchase price obligations	406.6		386.1
Long-term debt, including current portion	5,066.8		5,035.1
Carrying Amount
Assets:
Cash and cash equivalents	2,442.2		3,002.2
Short-term investments	43.6		20.6
Available-for-sale securities	4.0		4.3
Interest rate and foreign currency derivative instruments	0.5		0.2
Cost method investments	13.9		14.2
Liabilities:
Short-term debt	28.6		28.7
Interest rate and foreign currency derivative instruments	49.9		48.9
Contingent purchase price obligations	406.6		386.1
Long-term debt, including current portion	4,914.5		4,920.6
Contingent purchase price obligations
Changes in Level 3 Contingent Purchase Price Obligations [Roll Forward]
January 1	386.1	$ 322.0
Acquisitions	15.5	102.5
Revaluation and interest	(0.9)	12.3
Payments	(2.1)	(22.7)
Foreign currency translation	8.0	10.0
March 31	406.6	$ 424.1
Fair Value, Measurements, Recurring [Member]
Assets:
Cash and cash equivalents	2,442.2		3,002.2
Short-term investments	43.6		20.6
Available-for-sale securities	4.0		4.3
Interest rate and foreign currency derivative instruments	0.5		0.2
Liabilities:
Interest rate and foreign currency derivative instruments	49.9		48.9
Contingent purchase price obligations	406.6		386.1
Fair Value, Measurements, Recurring [Member] | Level 1
Assets:
Cash and cash equivalents	2,442.2		3,002.2
Short-term investments	43.6		20.6
Available-for-sale securities	4.0		4.3
Fair Value, Measurements, Recurring [Member] | Level 2
Assets:
Interest rate and foreign currency derivative instruments	0.5		0.2
Liabilities:
Interest rate and foreign currency derivative instruments	49.9		48.9
Fair Value, Measurements, Recurring [Member] | Level 3
Liabilities:
Contingent purchase price obligations	$ 406.6		$ 386.1