Fair Value (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Assets:
Cash and cash equivalents	$ 2,898.1		$ 3,652.4
Short-term investments	5.4		5.5
Marketable equity investments	1.5		1.5
Interest rate and foreign currency derivative instruments	4.9		0.0
Non-marketable equity securities	10.3		11.8
Liabilities:
Short-term debt	608.5		8.1
Interest rate and foreign currency derivative instruments	8.4		52.9
Contingent purchase price obligations	120.7		146.5
Long-term debt, including current portion	5,031.3		4,821.3
Carrying Amount
Assets:
Cash and cash equivalents	2,898.1		3,652.4
Short-term investments	5.4		5.5
Marketable equity investments	1.5		1.5
Interest rate and foreign currency derivative instruments	4.9		0.0
Non-marketable equity securities	10.3		11.8
Liabilities:
Short-term debt	608.5		8.1
Interest rate and foreign currency derivative instruments	8.4		52.9
Contingent purchase price obligations	120.7		146.5
Long-term debt, including current portion	4,925.4		4,883.7
Contingent purchase price obligations
Changes in Contingent Purchase Price Obligations [Roll Forward]
January 1	146.5	$ 215.6
Acquisitions	1.8	79.7
Revaluation and interest	1.5	4.9
Payments	(28.9)	(51.3)
Foreign currency translation	(0.2)	(13.6)
June 30	120.7	$ 235.3
Fair Value, Recurring [Member]
Assets:
Cash and cash equivalents	2,898.1		3,652.4
Short-term investments	5.4		5.5
Marketable equity investments	1.5		1.5
Interest rate and foreign currency derivative instruments	4.9
Liabilities:
Interest rate and foreign currency derivative instruments	8.4		52.9
Contingent purchase price obligations	120.7		146.5
Fair Value, Recurring [Member] | Level 1
Assets:
Cash and cash equivalents	2,898.1		3,652.4
Short-term investments	5.4		5.5
Marketable equity investments	1.5		1.5
Fair Value, Recurring [Member] | Level 2
Assets:
Interest rate and foreign currency derivative instruments	4.9
Liabilities:
Interest rate and foreign currency derivative instruments	8.4		52.9
Fair Value, Recurring [Member] | Level 3
Liabilities:
Contingent purchase price obligations	$ 120.7		$ 146.5