Basis of Presentation and Significant Accounting Policies (Derivative Financial Instruments) (Details) $ in Thousands	3 Months Ended	6 Months Ended
Dec. 30, 2017 USD ($) Contract	Jun. 30, 2018 USD ($) Contract
General Discussion of Derivative Instruments and Hedging Activities [Abstract]
Gain on foreign exchange contracts adjusted to fair value through earnings - less than	$ 100	$ 100
Foreign exchange contracts
General Discussion of Derivative Instruments and Hedging Activities [Abstract]
Total cost of contracts for Japanese yen (in thousands)	$ 2,204	$ 1,031
Number of contracts \| Contract	2	1

Amount of gain (loss) recognized in earnings in the period from the increase (decrease) in fair value of foreign currency derivatives not designated as hedging instruments.

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

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5624171-113959

Name:	us-gaap_GainLossOnForeignCurrencyDerivativeInstrumentsNotDesignatedAsHedgingInstruments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration