Derivatives - Amount of Gain (Loss) Recognized in OCI and Income Statement (Details) - Derivatives designated as cash flow hedges - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Interest rate swap
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain/(Loss) recognized in OCI	$ 853	$ 4,989	$ (571)
Interest rate swap \| Interest Expense
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain/(Loss) reclassified from AOCI	95	(718)	(1,103)
Foreign currency forward contracts
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain/(Loss) recognized in OCI		(205)	0
Foreign currency forward contracts \| Revenue
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain/(Loss) recognized in OCI	491
Amount of Gain/(Loss) reclassified from AOCI	(277)	21	0
Foreign currency forward contracts \| Cost of goods sold
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain/(Loss) reclassified from AOCI	$ 625	$ (26)	$ 0

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No definition available.

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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=64837297&loc=SL5624171-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4D
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=64837297&loc=SL5624177-113959

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- Definition

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

+ References

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