Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Taxes [Abstract]
Tax Act, provisional income tax expense			$ 106.3
Tax Act, provisional income tax expense, transition tax on accumulated foreign earnings			192.1
Tax Act, provisional income tax benefit, remeasurement of deferred tax assets and liabilities			173.3
Tax Act, provisional net cash liability, transition tax on accumulated foreign earnings			102.9
Income tax expense, dividends withholding tax on repatriation of foreign earnings			87.5
Tax Act, income tax expense	$ 0.0	$ 28.9
Tax Act, net cash liability, transition tax on accumulated foreign earnings	123.6	139.1
Income tax expense, GILTI	14.7	12.9
Income Before Income Taxes [Abstract]
Income before income taxes, Domestic	913.1	643.7	832.4
Income before income taxes, International	1,025.2	1,280.6	1,052.5
Income Before Income Taxes and Income From Equity Method Investments	1,938.3	1,924.3	1,884.9
Income Tax Expense [Abstract]
Income tax expense, current, Federal	180.2	273.8	458.8
Income tax expense, current, State and local	33.9	35.5	36.5
Income tax expense, current, International	306.9	305.2	280.2
Income tax expense, current	521.0	614.5	775.5
Income tax expense, deferred, Federal	19.1	(104.2)	(205.5)
Income tax expense, deferred, State and local	(22.5)	2.8	11.1
Income tax expense, deferred, International	(13.2)	(20.4)	115.1
Income tax expense, deferred	(16.6)	(121.8)	(79.3)
Income tax expense	$ 504.4	$ 492.7	$ 696.2
Reconciliation from the Statutory U.S. Federal Income Tax Rate to Effective Tax Rate [Abstract]
Statutory U.S. federal income tax rate	21.00%	21.00%	35.00%
U.S. state and local income taxes, net of U.S. federal income tax benefit	0.50%	1.60%	1.30%
Effect of Tax Act	0	0.015	0.056
International tax rate differentials	4.50%	3.80%	(3.80%)
Other	0.00%	(2.30%)	(1.20%)
Effective tax rate	26.00%	25.60%	36.90%
Effective Income Tax Rate Reconciliation, Tax Settlement, Amount	$ 10.8
Unrecognized Tax Benefits, Penalties and Interest [Abstract]
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense	2.2	$ 3.6	$ 2.5
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued	20.0	21.1
Deferred tax assets:
Compensation	210.9	209.7
Tax loss and credit carryforwards	60.6	38.1
Basis differences from acquisitions	22.9	13.9
Basis differences from short-term assets and liabilities	42.2	35.7
Other	4.6	10.8
Deferred tax assets	341.2	308.2
Valuation allowance	(7.6)	(3.0)
Net deferred tax assets	333.6	305.2
Deferred tax liabilities:
Goodwill and intangible assets	598.0	577.5
Unremitted foreign earnings	69.0	69.2
Basis differences from investments	9.0	9.6
Financial instruments	0.9	0.8
Deferred tax liabilities	676.9	657.1
Long-term deferred tax assets	64.8	61.8
Long-term deferred tax liabilities	408.1	413.7
Reconciliation of Unrecognized Tax Benefits [Roll Forward]
January 1	182.8	173.7
Current year tax positions	12.3	30.1
Prior year tax positions	29.4	5.2
Reduction of prior year tax positions	(13.1)	(25.4)
Settlements	5.0	0.0
Foreign currency translation	0.4
Foreign currency translation		(0.8)
December 31	206.8	182.8	$ 173.7
Unrecognized tax benefits that would impact effective tax rate	$ 179.0	$ 174.0