| Document and Entity Information | Mar. 04, 2020 |
| Cover [Abstract] | |
| Entity Registrant Name | WESTERN DIGITAL CORP |
| Amendment Flag | false |
| Entity Central Index Key | 0000106040 |
| Document Type | 8-K |
| Document Period End Date | Mar. 4, 2020 |
| Entity Incorporation State Country Code | DE |
| Entity File Number | 001-08703 |
| Entity Tax Identification Number | 33-0956711 |
| Entity Address, Address Line One | 5601 Great Oaks Parkway |
| Entity Address, City or Town | San Jose |
| Entity Address, State or Province | CA |
| Entity Address, Postal Zip Code | 95119 |
| City Area Code | (408) |
| Local Phone Number | 717-6000 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Security 12b Title | Common Stock, $.01 Par Value Per Share |
| Trading Symbol | WDC |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
