Document and Entity Information - USD ($)
12 Months Ended
Jun. 24, 2018
Aug. 09, 2018
Dec. 24, 2017
Document And Entity Information [Abstract]      
Document Type 10-K    
Amendment Flag false    
Document Period End Date Jun. 24, 2018    
Document Fiscal Year Focus 2018    
Document Fiscal Period Focus FY    
Trading Symbol LRCX    
Entity Registrant Name LAM RESEARCH CORP    
Entity Central Index Key 0000707549    
Current Fiscal Year End Date --06-24    
Entity Well-known Seasoned Issuer Yes    
Entity Current Reporting Status Yes    
Entity Voluntary Filers No    
Entity Filer Category Large Accelerated Filer    
Entity Common Stock, Shares Outstanding   157,579,984  
Entity Public Float     $ 24,908,278,746