| Document and Entity Information | Jan. 28, 2022 |
| Cover [Abstract] | |
| Entity Registrant Name | COMMERCIAL METALS Co |
| Amendment Flag | false |
| Entity Central Index Key | 0000022444 |
| Document Type | 8-K |
| Document Period End Date | Jan. 28, 2022 |
| Entity Incorporation State Country Code | DE |
| Entity File Number | 1-4304 |
| Entity Tax Identification Number | 75-0725338 |
| Entity Address, Address Line One | 6565 N. MacArthur Blvd. |
| Entity Address, City or Town | Irving |
| Entity Address, State or Province | TX |
| Entity Address, Postal Zip Code | 75039 |
| City Area Code | (214) |
| Local Phone Number | 689-4300 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Security 12b Title | Common stock, $0.01 par value |
| Trading Symbol | CMC |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
