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Derivative Contracts - Gain/(Loss) Recognized in Income on Derivative (Details) - Foreign Exchange Contracts - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Not Designated as Hedging Instruments | Change in Fair Value of Derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Derivative instruments not designated as hedging instruments, gain (loss), net	$ 7.2	$ 4.5	$ (15.4)	$ 25.2
Designated as Hedging Instrument | General and Administrative Expense
Derivative Instruments, Gain (Loss) [Line Items]
Foreign exchange contract settlement	(2.7)	1.2	0.3	2.4
Designated as Hedging Instrument | Net change from current period hedged transactions
Derivative Instruments, Gain (Loss) [Line Items]
Foreign exchange contracts, net change	$ (0.5)	$ (0.4)	$ (2.2)	$ 3.3

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

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Amount of realized and unrealized gain (loss) of derivative instruments not designated or qualifying as hedging instruments.

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Amount of gain (loss) from the increase (decrease) in fair value of foreign currency derivatives and nonderivative instruments designated as fair value hedging instruments which were recognized in earnings, net of offsets by the gain (loss) on the hedged item to the extent that the fair value hedge was determined to be effective.

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