Document and Entity Information - shares
9 Months Ended
Mar. 29, 2019
Apr. 30, 2019
Document And Entity Information [Abstract]    
Entity Registrant Name WESTERN DIGITAL CORP  
Entity Central Index Key 0000106040  
Current Fiscal Year End Date --06-28  
Entity Filer Category Large Accelerated Filer  
Entity Small Business false  
Entity Emerging Growth Company false  
Document Type 10-Q  
Document Period End Date Mar. 29, 2019  
Document Fiscal Year Focus 2019  
Document Fiscal Period Focus Q3  
Amendment Flag false  
Entity Common Stock, Shares Outstanding (in shares)   292,997,704
Entity Current Reporting Status Yes