Financial Instruments (Effect of Risk-Management Instruments) (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Cash flow hedges:
Total	$ (4.5)	$ 62.8	$ 48.2	$ 83.0
Foreign currency-denominated notes \| Net investment hedges
Cash flow hedges:
Effective portion of risk-management instruments that was recognized in other comprehensive income (loss)	(30.4)	208.5	23.3	100.8
Cross-currency interest rate swaps \| Net investment hedges
Cash flow hedges:
Effective portion of risk-management instruments that was recognized in other comprehensive income (loss)	(4.3)	69.1	34.0	37.6
Cross-currency interest rate swaps \| Cash flow hedges
Cash flow hedges:
Effective portion of risk-management instruments that was recognized in other comprehensive income (loss)	(7.4)	0.0	(37.5)	0.0
Forward-starting interest rate swaps \| Cash flow hedges
Cash flow hedges:
Effective portion of risk-management instruments that was recognized in other comprehensive income (loss)	0.0	0.0	(11.7)	0.0
Designated as Hedging Instrument \| Foreign currency-denominated notes
Fair value hedges:
Effect from hedged fixed-rate debt	59.3	(19.7)	98.5	(74.5)
Designated as Hedging Instrument \| Interest rate contracts
Fair value hedges:
Effect from interest rate contracts	(59.3)	19.7	(98.5)	74.5
Cash flow hedges:
Effective portion of losses on interest rate contracts reclassified from accumulated other comprehensive loss	4.0	3.7	7.8	7.3
Not Designated as Hedging Instrument \| Foreign currency exchange contracts
Cash flow hedges:
Net (gains) losses on foreign currency exchange contracts not designated as hedging instruments	$ (8.5)	$ 59.1	$ 40.4	$ 75.7

Cash Flow Hedge [Abstract]

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Derivative Instruments, Gain(loss) Recognized

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Fair Value Hedge [Abstract]

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Amount of gain (loss) from the increase (decrease) in fair value of derivative and nonderivative instruments designated as fair value hedging instruments recognized in the income statement.

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Amount of the increase (decrease) in fair value of the hedged item in a fair value hedge recognized in the income statement.

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The effective portion of loss reclassified from accumulated other comprehensive income into income on derivative instruments designated and qualifying as hedging instruments.

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Amount of gain (loss) recognized in earnings in the period from the increase (decrease) in fair value of foreign currency derivatives not designated as hedging instruments.

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Amount before tax of increase (decrease) in accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's increase (decrease) in deferred hedging gain (loss).

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