Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended			24 Months Ended	36 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2010	Dec. 31, 2016
Income Before Income Taxes [Abstract]
Income before income taxes, Domestic	$ 805.2	$ 803.3	$ 739.9
Income before income taxes, International	1,036.6	975.3	1,070.1
Income Before Income Taxes and Income From Equity Method Investments	1,841.8	1,778.6	1,810.0
Income Tax Expense [Abstract]
Income tax expense, current, Federal	381.8	342.3	356.1
Income tax expense, current, State and local	12.6	29.9	38.1
Income tax expense, current, International	332.1	324.5	344.8
Income tax expense, current	726.5	696.7	739.0
Income tax expense, deferred, Federal	(88.2)	(86.7)	(106.4)
Income tax expense, deferred, State and local	12.0	12.1	(2.3)
Income tax expense, deferred, International	(49.8)	(38.5)	(37.2)
Income tax expense, deferred	(126.0)	(113.1)	(145.9)
Income tax expense	$ 600.5	$ 583.6	$ 593.1
Reconciliation from the Statutory U.S. Federal Income Tax Rate to Effective Tax Rate [Abstract]
Statutory U.S. federal income tax rate	35.00%	35.00%	35.00%
State and local income taxes, net of federal income tax benefit	0.90%	1.50%	1.30%
International tax rate differentials	(4.00%)	(3.70%)	(3.30%)
Other	0.70%	0.00%	(0.20%)
Effective tax rate	32.60%	32.80%	32.80%
Unrecognized Tax Benefits, Penalties and Interest [Abstract]
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense	$ 2.3	$ 1.1	$ 1.7
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued	11.9	8.4			$ 11.9
Deferred tax assets:
Compensation	307.5	293.8			307.5
Tax loss and credit carryforwards	88.5	113.3			88.5
Basis differences from acquisitions	24.3	37.1			24.3
Basis differences from short-term assets and liabilities	36.2	27.2			36.2
Other	18.7	26.9			18.7
Deferred tax assets	475.2	498.3			475.2
Valuation allowance	(3.0)	(35.3)			(3.0)
Net deferred tax assets	472.2	463.0			472.2
Deferred tax liabilities:
Goodwill and intangible assets	802.7	729.5			802.7
Financial instruments	132.3	197.3			132.3
Unremitted foreign earnings	15.9	9.9			15.9
Basis differences from investments	1.8				1.8
Basis differences from investments		(4.6)
Deferred tax liabilities	952.7	932.1			952.7
Net deferred tax liabilities	480.5	469.1			480.5
Cumulative undistributed earnings of certain foreign subsidiaries indefinitely reinvested	2,400.0				2,400.0
Cumulative undistributed earnings of certain foreign subsidiaries not deemed to be indefinitely reinvested	1,300.0				1,300.0
Reconciliation of Unrecognized Tax Benefits [Roll Forward]
January 1	113.0	139.8
Current year tax positions	20.0	5.8
Prior year tax positions	6.5	0.2
Reduction of prior year tax positions	(21.9)	(25.1)
Settlements	(0.7)	(6.0)
Foreign currency translation	0.0	(1.7)
December 31	116.9	113.0	139.8		116.9
Unrecognized tax benefits that would impact effective tax rate	$ 71.0	$ 52.2			71.0
Convertible Debt [Member]
Deferred tax liabilities:
Convertible debt, repayments of convertible debt				$ 1,400.0
Convertible debt, repayments of convertible debt, deferred tax liability				$ 329.0
Taxes paid, cancellation of indebtedness income for debt reacquired					$ 197.0
Convertible Notes due July 31, 2032
Deferred tax liabilities:
Taxes Paid, Conversion of Convertible Debt			66.2
Convertible debt, adjustment to additional paid-in capital			$ 32.2
Minimum [Member]
Deferred tax liabilities:
Tax loss and credit carryforwards, expiration dates	Dec. 31, 2017
Maximum [Member]
Deferred tax liabilities:
Tax loss and credit carryforwards, expiration dates	Dec. 31, 2036