| Cover Page Document | Jan. 02, 2020 |
| Cover Page [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Jan. 2, 2020 |
| Entity Registrant Name | Illumina, Inc. |
| Entity File Number | 001-35406 |
| Entity Incorporation, State or Country Code | DE |
| Entity Tax Identification Number | 33-0804655 |
| Entity Address, Address Line One | 5200 Illumina Way |
| Entity Address, City or Town | San Diego |
| Entity Address, State or Province | CA |
| Entity Address, Postal Zip Code | 92122 |
| City Area Code | 858 |
| Local Phone Number | 202-4500 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock, $0.01 par value |
| Trading Symbol | ILMN |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
| Entity Central Index Key | 0001110803 |
| Amendment Flag | false |
