Document and Entity Information Document - USD ($) shares in Millions, $ in Billions	12 Months Ended
	Jan. 01, 2017	Feb. 03, 2017	Jul. 03, 2016
Document and Entity Information [Abstract]
Entity Registrant Name	Illumina Inc
Entity Central Index Key	0001110803
Current Fiscal Year End Date	--01-01
Entity Filer Category	Large Accelerated Filer
Document Type	10-K
Document Period End Date	Jan. 01, 2017
Document Fiscal Year Focus	2016
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Common Stock, Shares Outstanding		146.3
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 17.9