v3.8.0.1

Segment Information, Geographic Data, and Significant Customers - Summary of Operating Performance and Assets by Segment (Details) - USD ($) $ in Millions | 3 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 31, 2017 | Oct. 01, 2017 | Jul. 02, 2017 | Apr. 02, 2017 | Jan. 01, 2017 | Oct. 02, 2016 | Jul. 03, 2016 | Apr. 03, 2016 | Dec. 31, 2017 | Jan. 01, 2017 | Jan. 03, 2016
Segment Reporting Information [Line Items] |  |  |  |  |  |  |  |  |  |  |
Segment revenues | $ 778 | $ 714 | $ 662 | $ 598 | $ 619 | $ 607 | $ 600 | $ 572 | $ 2,752 | $ 2,398 | $ 2,220
Segment depreciation and amortization |  |  |  |  |  |  |  |  | 156 | 141 | 127
Segment operating income (loss) |  |  |  |  |  |  |  |  | 606 | 587 | 613
Segment assets | 5,257 |  |  |  | 4,281 |  |  |  | 5,257 | 4,281 | 3,688
Segment capital expenditures |  |  |  |  |  |  |  |  | 310 | 260 | 143
Eliminations [Member] |  |  |  |  |  |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |  |  |  |  |  |
Segment revenues |  |  |  |  |  |  |  |  | (8) | (30) |
Segment depreciation and amortization |  |  |  |  |  |  |  |  | (3) | (1) |
Segment operating income (loss) |  |  |  |  |  |  |  |  | 2 | (16) |
Segment assets | (11) |  |  |  | (66) |  |  |  | (11) | (66) | (1)
Operating Segments [Member] | Core Illumina [Member] |  |  |  |  |  |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |  |  |  |  |  |
Segment revenues |  |  |  |  |  |  |  |  | 2,754 | 2,428 | 2,220
Segment depreciation and amortization |  |  |  |  |  |  |  |  | 153 | 138 | 127
Segment operating income (loss) |  |  |  |  |  |  |  |  | 696 | 684 | 621
Segment assets | 5,223 |  |  |  | 4,167 |  |  |  | 5,223 | 4,167 | 3,658
Segment capital expenditures |  |  |  |  |  |  |  |  | 306 | 238 | 142
Operating Segments [Member] | Consolidated VIEs [Member] |  |  |  |  |  |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |  |  |  |  |  |
Segment revenues |  |  |  |  |  |  |  |  | 6 |  |
Segment depreciation and amortization |  |  |  |  |  |  |  |  | 6 | 4 |
Segment operating income (loss) |  |  |  |  |  |  |  |  | (92) | (81) | (8)
Segment assets | $ 45 |  |  |  | $ 180 |  |  |  | 45 | 180 | 31
Segment capital expenditures |  |  |  |  |  |  |  |  | $ 4 | $ 22 | $ 1

X
- Definition Segment Capital Expenditures + References No definition available. + Details
Name: | ilmn_SegmentCapitalExpenditures
Namespace Prefix: | ilmn_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(12)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(11)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 + Details
Name: | us-gaap_Assets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The aggregate expense recognized in the current period that allocates the cost of tangible assets, intangible assets, or depleting assets to periods that benefit from use of the assets. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585 + Details
Name: | us-gaap_DepreciationDepletionAndAmortization
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The net result for the period of deducting operating expenses from operating revenues. + References No definition available. + Details
Name: | us-gaap_OperatingIncomeLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Total revenue from sale of goods and services rendered during the reporting period, in the normal course of business, reduced by sales returns and allowances, and sales discounts. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.1) -URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688 + Details
Name: | us-gaap_SalesRevenueNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
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
Name: | us-gaap_SegmentReportingInformationLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=us-gaap_IntersegmentEliminationMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ConsolidationItemsAxis=us-gaap_OperatingSegmentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=ilmn_CoreIlluminaMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=ilmn_ConsolidatedVariableInterestEntitiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |