Derivative Financial Instruments - Non-designated Hedges (Details) - Not designated as hedging instrument - Foreign currency forward contracts $ in Thousands	3 Months Ended	9 Months Ended
Sep. 29, 2018 USD ($) contract	Sep. 30, 2017 USD ($) contract	Sep. 29, 2018 USD ($) contract	Sep. 30, 2017 USD ($) contract
Derivative Instruments, Gain (Loss)
Number of foreign currency forward contract held \| contract	1	1	1	1
Notional value	$ 1,600	$ 3,200	$ 1,600	$ 3,200
Interest income and other, net
Derivative Instruments, Gain (Loss)
Loss Recognized in Income	$ (6)	$ (203)	$ (13)	$ (332)

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

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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Amount of increase (decrease) in the fair value of derivatives recognized in the income statement.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4A
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5618551-113959

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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 foreign currency exchange rate derivatives held by the entity at the reporting date.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5579245-113959

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1B
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5580258-113959

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