v3.8.0.1

Organization and Summary of Significant Accounting Policies - Narrative - Warranties (Details)	12 Months Ended
	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: