| Cover | Sep. 09, 2020 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Sep. 9, 2020 |
| Entity File Number | 1-14315 |
| Entity Registrant Name | Cornerstone Building Brands, Inc. |
| Entity Central Index Key | 0000883902 |
| Entity Tax Identification Number | 76-0127701 |
| Entity Incorporation, State or Country Code | DE |
| Entity Address, Address Line One | 5020 Weston Parkway |
| Entity Address, Address Line Two | Suite 400 |
| Entity Address, City or Town | Cary |
| Entity Address, State or Province | NC |
| Entity Address, Postal Zip Code | 27513 |
| City Area Code | 866 |
| Local Phone Number | 419-0042 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock $.01 par value per share |
| Trading Symbol | CNR |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
