| Document and Entity Information | Jun. 30, 2020 |
| Cover [Abstract] | |
| Entity Registrant Name | CONAGRA BRANDS INC. |
| Amendment Flag | false |
| Entity Central Index Key | 0000023217 |
| Document Type | 8-K |
| Document Period End Date | Jun. 30, 2020 |
| Entity Incorporation State Country Code | DE |
| Entity File Number | 1-7275 |
| Entity Tax Identification Number | 47-0248710 |
| Entity Address, Address Line One | 222 Merchandise Mart |
| Entity Address, Address Line Two | Plaza |
| Entity Address, Address Line Three | Suite 1300 |
| Entity Address, City or Town | Chicago |
| Entity Address, State or Province | IL |
| Entity Address, Postal Zip Code | 60654 |
| City Area Code | (312) |
| Local Phone Number | 549-5000 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Security 12b Title | Common Stock, $5.00 par value |
| Trading Symbol | CAG |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
