Derivative Financial Instruments and Credit Risk - Narrative (Details) $ in Millions	12 Months Ended
Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Derivative [Line Items]
Derivative, fair value	$ 5.5	$ 5.0
Foreign Exchange Contract
Derivative [Line Items]
Derivative asset, notional amount	$ 421.2
Interest Rate Swap
Derivative [Line Items]
Number of interest rate derivatives held	3
Cash Flow Hedging \| Designated as Hedging Instrument
Derivative [Line Items]
Derivative, effective portion recognized in other comprehensive income (loss)	$ 1.3
Cash Flow Hedging \| Designated as Hedging Instrument \| Interest Rate Swap
Derivative [Line Items]
Derivative, fair value	$ 2.0

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

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5579245-113959

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- Definition

The effective portion of gains on derivative instruments designated and qualifying as hedging instruments that was recognized in other comprehensive income during the current period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
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- Definition

Fair value, after the 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 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
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-Section 55
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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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- Definition

Number of interest rate derivative instruments held by the entity at the reporting date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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