Derivatives and Hedging Activities Derivative Balance Sheet Location (Details) - Foreign Exchange Forward [Member] - Designated as Hedging Instrument [Member] - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Prepaid Expenses and Other Current Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset	$ 187	$ 0
Other Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset	545	0
Accrued Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability	0	187
Other Noncurrent Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability	0	402
Derivative Financial Instruments, Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability	$ 732	$ 589

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.

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 (c)
-URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=109250915&loc=d3e13433-108611

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=99393222&loc=SL20226008-175313

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant