Fair Value (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Assets:
Short-term investments	$ 3.6	$ 5.5
Liabilities:
Contingent purchase price obligations	107.7	146.5
Carrying Amount
Assets:
Cash and cash equivalents	4,305.7	3,652.4
Short-term investments	3.6	5.5
Marketable equity securities	1.6	1.5
Non-marketable equity securities	9.0	11.8
Foreign currency derivatives	0.6	0.0
Liabilities:
Short-term debt	10.1	8.1
Interest rate derivatives	0.0	52.8
Foreign currency derivatives	0.4	0.1
Contingent purchase price obligations	107.7	146.5
Long-term debt, including current portion	5,134.3	4,883.7
Fair Value
Assets:
Cash and cash equivalents	4,305.7	3,652.4
Short-term investments	3.6	5.5
Marketable equity securities	1.6	1.5
Non-marketable equity securities	9.0	11.8
Foreign currency derivatives	0.6	0.0
Liabilities:
Short-term debt	10.1	8.1
Interest rate derivatives	0.0	52.8
Foreign currency derivatives	0.4	0.1
Contingent purchase price obligations	107.7	146.5
Long-term debt, including current portion	5,316.4	4,821.3
Contingent purchase price obligations
Changes in Contingent Purchase Price Obligations [Roll Forward]
January 1	146.5	215.6
Acquisitions	51.1	85.8
Revaluation and interest	(18.0)	(30.1)
Payments	(71.4)	(100.3)
Foreign currency translation	(0.5)	(24.5)
December 31	107.7	146.5
Fair Value, Recurring [Member]
Assets:
Cash and cash equivalents	4,305.7	3,652.4
Short-term investments	3.6	5.5
Marketable equity securities	1.6	1.5
Foreign currency derivatives	0.6
Liabilities:
Interest rate derivatives		52.8
Foreign currency derivatives	0.4	0.1
Contingent purchase price obligations	107.7	146.5
Fair Value, Recurring [Member] | Level 1
Assets:
Cash and cash equivalents	4,305.7	3,652.4
Short-term investments	3.6	5.5
Marketable equity securities	1.6	1.5
Fair Value, Recurring [Member] | Level 2
Assets:
Foreign currency derivatives	0.6
Liabilities:
Interest rate derivatives		52.8
Foreign currency derivatives	0.4	0.1
Fair Value, Recurring [Member] | Level 3
Liabilities:
Contingent purchase price obligations	$ 107.7	$ 146.5