| Document and Entity Information | Jan. 03, 2020 |
| Document and Entity Information [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Jan. 3, 2020 |
| Entity File Number | 1-37830 |
| Entity Registrant Name | Lamb Weston Holdings, Inc. |
| Entity Incorporation, State or Country Code | DE |
| Entity Tax Identification Number | 61-1797411 |
| Entity Address, Address Line One | 599 S. Rivershore Lane |
| Entity Address, City or Town | Eagle |
| Entity Address, State or Province | ID |
| Entity Address, Postal Zip Code | 83616 |
| City Area Code | 208 |
| Local Phone Number | 938-1047 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock, $1.00 par value |
| Trading Symbol | LW |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
| Entity Central Index Key | 0001679273 |
| Amendment Flag | false |
