v3.8.0.1
Document and Entity Information - shares
3 Months Ended
Sep. 29, 2017
Oct. 31, 2017
Document And Entity Information [Abstract]    
Entity Registrant Name WESTERN DIGITAL CORP  
Entity Central Index Key 0000106040  
Current Fiscal Year End Date --06-29  
Entity Filer Category Large Accelerated Filer  
Document Type 10-Q  
Document Period End Date Sep. 29, 2017  
Document Fiscal Year Focus 2018  
Document Fiscal Period Focus Q1  
Amendment Flag false  
Entity Common Stock, Shares Outstanding (in shares)   295,786,618
Entity Well-known Seasoned Issuer Yes  
Entity Voluntary Filers No  
Entity Current Reporting Status Yes