Fair Value (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Assets:
Cash and cash equivalents	$ 1,834.0		$ 3,002.2
Short-term investments	40.4		20.6
Available-for-sale securities	4.0		4.3
Interest rate and foreign currency derivative instruments	0.2		0.2
Cost method investments	13.9		14.2
Liabilities:
Short-term debt	19.3		28.7
Interest rate and foreign currency derivative instruments	30.8		48.9
Contingent purchase price obligations	268.2		386.1
Long-term debt, including current portion	5,098.8		5,035.1
Carrying Amount
Assets:
Cash and cash equivalents	1,834.0		3,002.2
Short-term investments	40.4		20.6
Available-for-sale securities	4.0		4.3
Interest rate and foreign currency derivative instruments	0.2		0.2
Cost method investments	13.9		14.2
Liabilities:
Short-term debt	19.3		28.7
Interest rate and foreign currency derivative instruments	30.8		48.9
Contingent purchase price obligations	268.2		386.1
Long-term debt, including current portion	4,930.0		4,920.6
Contingent purchase price obligations
Changes in Level 3 Contingent Purchase Price Obligations [Roll Forward]
January 1	386.1	$ 322.0
Acquisitions	22.2	150.8
Revaluation and interest	(0.4)	13.8
Payments	(146.4)	(62.7)
Foreign currency translation	6.7	6.5
June 30	268.2	$ 430.4
Fair Value, Measurements, Recurring [Member]
Assets:
Cash and cash equivalents	1,834.0		3,002.2
Short-term investments	40.4		20.6
Available-for-sale securities	4.0		4.3
Interest rate and foreign currency derivative instruments	0.2		0.2
Liabilities:
Interest rate and foreign currency derivative instruments	30.8		48.9
Contingent purchase price obligations	268.2		386.1
Fair Value, Measurements, Recurring [Member] | Level 1
Assets:
Cash and cash equivalents	1,834.0		3,002.2
Short-term investments	40.4		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	0.2		0.2
Liabilities:
Interest rate and foreign currency derivative instruments	30.8		48.9
Fair Value, Measurements, Recurring [Member] | Level 3
Liabilities:
Contingent purchase price obligations	$ 268.2		$ 386.1