Derivative Instruments and Hedging Activities - Fair Value of Outstanding Derivatives (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Asset Derivatives	$ 8,085	$ 17,633
Liability Derivatives	1,258	5,409
Derivatives designated as hedging instruments \| Interest rate contracts \| Other current assets
Derivatives, Fair Value [Line Items]
Asset Derivatives	2,150
Derivatives designated as hedging instruments \| Interest rate contracts \| Other non-current assets
Derivatives, Fair Value [Line Items]
Asset Derivatives	5,674	2,138
Derivatives designated as hedging instruments \| Interest rate contracts \| Accrued liabilities
Derivatives, Fair Value [Line Items]
Liability Derivatives	0	392
Derivatives not designated as hedging instruments \| Foreign exchange forward contracts \| Other current assets
Derivatives, Fair Value [Line Items]
Asset Derivatives	261	15,495
Derivatives not designated as hedging instruments \| Foreign exchange forward contracts \| Accrued liabilities
Derivatives, Fair Value [Line Items]
Liability Derivatives	$ 1,258	$ 5,017

Fair value, before 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 elected not to be offset.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312

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- Definition

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 not subject to a master netting arrangement and elected not to be offset.

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- Definition

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