Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Before Income Taxes [Abstract]
Income before income taxes, Domestic	$ 711.1	$ 913.1	$ 643.7
Income before income taxes, International	698.2	1,025.2	1,280.6
Income Before Income Taxes and Income (Loss) From Equity Method Investments	1,409.3	1,938.3	1,924.3
Income Tax Expense [Abstract]
Income tax expense, current, Federal	172.2	180.2	273.8
Income tax expense, current, State and local	39.5	33.9	35.5
Income tax expense, current, International	189.1	306.9	305.2
Income tax expense, current	400.8	521.0	614.5
Income tax expense, deferred, Federal	(17.4)	19.1	(104.2)
Income tax expense, deferred, State and local	(6.1)	(22.5)	2.8
Income tax expense, deferred, International	4.4	(13.2)	(20.4)
Income tax expense, deferred	(19.1)	(16.6)	(121.8)
Income tax expense	$ 381.7	$ 504.4	$ 492.7
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%	21.00%
U.S. state and local income taxes, net of U.S. federal income tax benefit	2.20%	0.50%	1.60%
Effect of Tax Act	0	0	0.015
Impact of foreign operations	3.40%	4.50%	3.80%
Other	0.50%	0.00%	(2.30%)
Effective tax rate	27.10%	26.00%	25.60%
Income tax benefit, resolution of uncertain tax positions and tax claims		$ 10.8
Tax Act, net cash liability, transition tax on accumulated foreign earnings	$ 112.0	123.6
Income tax expense, GILTI	3.0	14.7
Unrecognized Tax Benefits, Penalties and Interest [Abstract]
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense	3.8	2.2	$ 3.6
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued	23.5	20.0
Deferred tax assets:
Compensation	236.5	210.9
Tax loss and credit carryforwards	67.0	60.6
Basis differences from acquisitions	20.8	22.9
Basis differences from short-term assets and liabilities	34.4	42.2
Other	(5.8)
Other		4.6
Deferred tax assets	352.9	341.2
Valuation allowance	(15.9)	(7.6)
Net deferred tax assets	337.0	333.6
Deferred tax liabilities:
Goodwill and intangible assets	611.1	598.0
Unremitted foreign earnings	91.9	69.0
Basis differences from investments	(1.1)
Basis differences from investments		9.0
Financial instruments	0.8	0.9
Deferred tax liabilities	702.7	676.9
Long-term deferred tax liabilities	443.5	408.1
Reconciliation of Unrecognized Tax Benefits [Roll Forward]
January 1	206.8	182.8
Current year tax positions	3.9	12.3
Prior year tax positions	2.8	29.4
Reduction of prior year tax positions	(26.1)	(13.1)
Settlements	(2.5)	(5.0)
Foreign currency translation	(2.0)
Foreign currency translation		0.4
December 31	182.9	206.8	$ 182.8
Unrecognized tax benefits that would impact effective tax rate	174.0	179.0
Other Assets
Long-term deferred tax assets	$ 77.8	$ 64.8