| Document and Entity Information | May 05, 2020 |
| Cover [Abstract] | |
| Entity Registrant Name | LAM RESEARCH CORP |
| Amendment Flag | false |
| Entity Central Index Key | 0000707549 |
| Document Type | 8-K |
| Document Period End Date | May 5, 2020 |
| Entity Incorporation State Country Code | DE |
| Entity File Number | 0-12933 |
| Entity Tax Identification Number | 94-2634797 |
| Entity Address, Address Line One | 4650 Cushing Parkway |
| Entity Address, City or Town | Fremont |
| Entity Address, State or Province | CA |
| Entity Address, Postal Zip Code | 94538 |
| City Area Code | (510) |
| Local Phone Number | 572-0200 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Security 12b Title | Common Stock, Par Value $0.001 Per Share |
| Trading Symbol | LRCX |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
