| Document and Entity Information | Jan. 07, 2021 |
| Document And Entity Information [Line Items] | |
| Entity Registrant Name | General Mills, Inc. |
| Amendment Flag | false |
| Entity Central Index Key | 0000040704 |
| Document Type | 8-K |
| Document Period End Date | Jan. 7, 2021 |
| Entity Incorporation State Country Code | DE |
| Entity File Number | 001-01185 |
| Entity Tax Identification Number | 41-0274440 |
| Entity Address, Address Line One | Number One General Mills Boulevard |
| Entity Address, City or Town | Minneapolis |
| Entity Address, State or Province | MN |
| Entity Address, Postal Zip Code | 55426 |
| City Area Code | (763) |
| Local Phone Number | 764-7600 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
| Common Stock [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | Common Stock, $.10 par value |
| Trading Symbol | GIS |
| Security Exchange Name | NYSE |
| One Point Zero Zero Zero Percent Notes Due 2023 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 1.000% Notes due 2023 |
| Trading Symbol | GIS23A |
| Security Exchange Name | NYSE |
| Zero Point Four Five Zero Percent Notes Due 2026 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 0.450% Notes due 2026 |
| Trading Symbol | GIS26 |
| Security Exchange Name | NYSE |
| One Point Five Zero Zero Percent Notes Due 2027 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 1.500% Notes due 2027 |
| Trading Symbol | GIS27 |
| Security Exchange Name | NYSE |
