Investments (Details) - USD ($) $ in Thousands	Mar. 30, 2019	Dec. 29, 2018
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	$ 616,054	$ 578,512
Gross Unrealized Gains	101	1
Gross Unrealized Losses	(355)	(1,104)
Available-for-sale Securities	615,800	577,409
Cash equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	213,974	157,932
Available-for-sale Securities	213,974	157,932
Cash equivalents [Member] \| Money market funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	77,709	76,471
Available-for-sale Securities	77,709	76,471
Cash equivalents [Member] \| Time deposits [Member]
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	63,300	71,461
Available-for-sale Securities	63,300	71,461
Cash equivalents [Member] \| Commercial paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	72,965	10,000
Available-for-sale Securities	72,965	10,000
Short-term investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	400,761	402,333
Gross Unrealized Gains	101	1
Gross Unrealized Losses	(353)	(1,049)
Available-for-sale Securities	400,509	401,285
Short-term investments [Member] \| Time deposits [Member]
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	35,011	31,947
Available-for-sale Securities	35,011	31,947
Short-term investments [Member] \| Commercial paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	85,631	75,445
Gross Unrealized Gains	17
Gross Unrealized Losses	(30)	(91)
Available-for-sale Securities	85,618	75,354
Short-term investments [Member] \| Government and corporate bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	280,119	294,941
Gross Unrealized Gains	84	1
Gross Unrealized Losses	(323)	(958)
Available-for-sale Securities	279,880	293,984
Long-term investments [Member] \| Government and corporate bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	1,319	18,247
Gross Unrealized Losses	(2)	(55)
Available-for-sale Securities	$ 1,317	$ 18,192

Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt securities classified as available-for-sale.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27161-111563

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Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt securities classified as available-for-sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
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Reference 2: http://www.xbrl.org/2003/role/presentationRef
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.2)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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