Fair Value (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Assets:
Short-term investments	$ 0.0		$ 3.6
Carrying Amount
Assets:
Cash and cash equivalents	3,281.0		4,305.7
Short-term investments	0.0		3.6
Marketable equity securities	1.6		1.6
Non-marketable equity securities	8.7		9.0
Foreign currency derivatives	0.5		0.6
Liabilities:
Short-term debt	6.4		10.1
Foreign currency derivatives	0.8		0.4
Contingent purchase price obligations	104.3		107.7
Long-term debt, including current portion	5,714.1		5,134.3
Fair Value
Assets:
Cash and cash equivalents	3,281.0		4,305.7
Short-term investments	0.0		3.6
Marketable equity securities	1.6		1.6
Non-marketable equity securities	8.7		9.0
Foreign currency derivatives	0.5		0.6
Liabilities:
Short-term debt	6.4		10.1
Foreign currency derivatives	0.8		0.4
Contingent purchase price obligations	104.3		107.7
Long-term debt, including current portion	6,122.6		5,316.4
Contingent purchase price obligations
Changes in Contingent Purchase Price Obligations [Roll Forward]
January 1	107.7	$ 146.5
Acquisitions	10.0	1.8
Revaluation and interest	1.6	1.5
Payments	(12.8)	(28.9)
Foreign currency translation	(2.2)	(0.2)
June 30	104.3	$ 120.7
Fair Value, Recurring [Member]
Assets:
Cash and cash equivalents	3,281.0		4,305.7
Short-term investments	0.0		3.6
Marketable equity securities	1.6		1.6
Foreign currency derivatives	0.5		0.6
Liabilities:
Foreign currency derivatives	0.8		0.4
Contingent purchase price obligations	104.3		107.7
Fair Value, Recurring [Member] | Level 1
Assets:
Cash and cash equivalents	3,281.0		4,305.7
Short-term investments	0.0		3.6
Marketable equity securities	1.6		1.6
Fair Value, Recurring [Member] | Level 2
Assets:
Foreign currency derivatives	0.5		0.6
Liabilities:
Foreign currency derivatives	0.8		0.4
Fair Value, Recurring [Member] | Level 3
Liabilities:
Contingent purchase price obligations	$ 104.3		$ 107.7