v3.8.0.1
Document and Entity Information Document - USD ($)
shares in Millions, $ in Billions
12 Months Ended
Dec. 31, 2017
Feb. 09, 2018
Jul. 02, 2017
Document and Entity Information [Abstract]      
Entity Registrant Name Illumina Inc    
Entity Central Index Key 0001110803    
Current Fiscal Year End Date --12-31    
Entity Filer Category Large Accelerated Filer    
Document Type 10-K    
Document Period End Date Dec. 31, 2017    
Document Fiscal Year Focus 2017    
Document Fiscal Period Focus FY    
Amendment Flag false    
Entity Common Stock, Shares Outstanding   147  
Entity Well-known Seasoned Issuer Yes    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Public Float     $ 22.0