v3.8.0.1

Organization and Summary of Significant Accounting Policies - Narrative - Warranties (Details) | 12 Months Ended
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Dec. 31, 2017
Instruments [Member] |
Product Warranty Liability [Line Items] |
Warranty period | 1 year
Consumables [Member] | Minimum [Member] |
Product Warranty Liability [Line Items] |
Warranty period | 6 months
Consumables [Member] | Maximum [Member] |
Product Warranty Liability [Line Items] |
Warranty period | 12 months

X
- Definition Describes the approximate term of the product warranty. + References No definition available. + Details
Name: | ilmn_StandardProductWarrantyDescriptionTerm
Namespace Prefix: | ilmn_
Data Type: | xbrli:durationItemType
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
Name: | us-gaap_ProductWarrantyLiabilityLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_ProductOrServiceAxis=ilmn_InstrumentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ProductOrServiceAxis=ilmn_ConsumablesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |