Schedule of Geographic Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
Apr. 03, 2020	Mar. 29, 2019
Segment Reporting Information [Line Items]
Revenue	$ 155,468	$ 157,186
United States
Segment Reporting Information [Line Items]
Revenue	59,205	64,760
Germany
Segment Reporting Information [Line Items]
Revenue	23,233	23,477
Rest of Europe
Segment Reporting Information [Line Items]
Revenue	33,085	30,770
China
Segment Reporting Information [Line Items]
Revenue	15,404	15,108
Rest of Asia-Pacific
Segment Reporting Information [Line Items]
Revenue	21,700	20,447
Other Countries
Segment Reporting Information [Line Items]
Revenue	$ 2,841	$ 2,624

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130543-203045

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130545-203045

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