| Document and Entity Information | Mar. 12, 2021 |
| Cover [Abstract] | |
| Security Exchange Name | NASDAQ |
| Amendment Flag | false |
| Entity Central Index Key | 0001110803 |
| Document Type | 8-K |
| Document Period End Date | Mar. 12, 2021 |
| Entity Registrant Name | Illumina, Inc. |
| Entity File Number | 001-35406 |
| Entity Incorporation State 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 | true |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Security 12b Title | Common Stock, $0.01 par value |
| Trading Symbol | ILMN |
| Entity Emerging Growth Company | false |
