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Derivative Contracts - Fair Value of Derivative Instruments (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Derivatives at fair value	$ 14.1	$ 6.4
Foreign Exchange Contracts | Not Designated as Hedging Instruments
Derivatives, Fair Value [Line Items]
Derivative notional amount	1,153.3	751.6
Cash collateral provided	2.3	0.6
Foreign Exchange Contracts | Not Designated as Hedging Instruments | Derivatives at Fair Value
Derivatives, Fair Value [Line Items]
Derivative notional amount	340.9	577.7
Foreign Exchange Contracts | Not Designated as Hedging Instruments | Liabilities under Derivative Contracts
Derivatives, Fair Value [Line Items]
Liability notional amount	812.4	173.9
Foreign Exchange Contracts | Designated as Hedging Instrument | Derivatives at Fair Value
Derivatives, Fair Value [Line Items]
Derivative notional amount	114.3	60.6
Level 2 | Fair Value, Measurements, Recurring | Foreign Exchange Contracts | Not Designated as Hedging Instruments | Derivatives at Fair Value
Derivatives, Fair Value [Line Items]
Derivatives at fair value	14.2	5.0
Level 2 | Fair Value, Measurements, Recurring | Foreign Exchange Contracts | Not Designated as Hedging Instruments | Liabilities under Derivative Contracts
Derivatives, Fair Value [Line Items]
Liabilities at fair value	(49.3)	(1.0)
Level 2 | Fair Value, Measurements, Recurring | Foreign Exchange Contracts | Designated as Hedging Instrument | Derivatives at Fair Value
Derivatives, Fair Value [Line Items]
Derivatives at fair value	$ (0.1)	$ 1.4

X

- Definition

Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 12
-Section 13
-Sentence Column B

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- Definition

The aggregate fair value of assets that are already posted, at the end of the reporting period, as collateral for derivative instruments with credit-risk-related contingent features.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4H
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5624258-113959

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- Definition

Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312

Reference 2: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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Fair value, before effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
-Topic 860
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- Definition

Nominal or face amount used to calculate payments on the derivative liability.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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-SubTopic 10
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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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