v3.8.0.1

Segment Information, Geographic Data, and Significant Customers - Narrative (Details) - Sales revenue, net [Member] - Product concentration risk [Member]	12 Months Ended
	Dec. 31, 2017	Jan. 01, 2017	Jan. 03, 2016
Products and services, consumables [Member]
Revenue from External Customer [Line Items]
Percent of sales	64.00%	64.00%	58.00%
Products and services, instruments [Member]
Revenue from External Customer [Line Items]
Percent of sales	19.00%	20.00%	27.00%

X

- Definition

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 18
-URI http://asc.fasb.org/extlink&oid=84177426&loc=d3e6351-108592

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=77997519&loc=d3e13531-108611

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=84177426&loc=d3e6404-108592

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 21
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=77997519&loc=d3e13537-108611

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

X

- Definition

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.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Details

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Namespace Prefix:
Data Type:	na
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X

- Details

Name:	us-gaap_ConcentrationRiskByTypeAxis=us-gaap_ProductConcentrationRiskMember
Namespace Prefix:
Data Type:	na
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Period Type:

X

- Details

Name:	us-gaap_ProductOrServiceAxis=ilmn_ProductsAndServicesConsumablesMember
Namespace Prefix:
Data Type:	na
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Period Type:

X

- Details

Name:	us-gaap_ProductOrServiceAxis=ilmn_ProductsAndServicesInstrumentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: