Segment information Total net revenues by geographic region (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2018	Oct. 01, 2017	Sep. 30, 2018	Oct. 01, 2017
Segment Reporting Information [Line Items]
Net revenues	$ 609,672	$ 534,703	$ 1,806,768	$ 1,551,197
United States
Segment Reporting Information [Line Items]
Net revenues	365,271	306,763	1,066,095	903,201
Europe
Segment Reporting Information [Line Items]
Net revenues	160,498	148,808	500,697	434,223
Asia
Segment Reporting Information [Line Items]
Net revenues	60,414	59,169	170,458	156,074
All Other
Segment Reporting Information [Line Items]
Net revenues	$ 23,489	$ 19,963	$ 69,518	$ 57,699

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://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130543-203045

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130539-203045

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130545-203045

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Period Type:	duration