| Document and Entity Information | Aug. 18, 2021 |
| Cover [Abstract] | |
| Amendment Flag | true |
| Entity Central Index Key | 0001110803 |
| Document Type | 8-K/A |
| Document Period End Date | Aug. 18, 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 | false |
| 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 |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
| Amendment Description | On August 18, 2021, Illumina, Inc., a Delaware corporation (“Illumina”), filed a Current Report on Form 8-K (the “Original 8-K”) to report the consummation of the transactions contemplated by the Agreement and Plan of Merger, dated as of September 20, 2020 (the “Original Merger Agreement”) (such transactions, the “Transaction”), as amended on February 4, 2021 by the Amendment to the Agreement and Plan of Merger (the “Merger Agreement Amendment” and the Original Merger Agreement as amended by the Merger Agreement Amendment, the “Merger Agreement”), by and among Illumina, GRAIL, Inc., a Delaware corporation (“GRAIL”), SDG Ops, Inc., a Delaware corporation and a direct, wholly owned subsidiary of Illumina (“First Merger Sub”), SDG Ops, LLC, a Delaware limited liability company and a direct, wholly owned subsidiary of Illumina (“Second Merger Sub” and now known as GRAIL, LLC). Pursuant to the Merger Agreement, First Merger Sub merged with and into GRAIL, with GRAIL continuing as the surviving entity and as a direct, wholly owned subsidiary of Illumina (the “First Merger”). Immediately following the First Merger and as part of the same overall transaction as the First Merger, GRAIL merged with and into Second Merger Sub, with Second Merger Sub being renamed GRAIL, LLC and continuing as the surviving entity and as a direct, wholly owned subsidiary of Illumina. This Current Report on Form 8-K/A (this “Amended 8-K”) amends and supplements the Original 8-K filed by Illumina, and is being filed to provide the historical statements and the pro forma financial information required pursuant to Items 9.01(a) and 9.01(b) of Form 8-K, respectively. In accordance with the requirements of Items 9.01(a)(3) and 9.01(b)(2) of Form 8-K, this Amended 8-K is being filed within 71 calendar days of the date that the Original 8-K was required to be filed with respect to the above referenced transaction. |
