| Document and Entity Information | Dec. 17, 2020 |
| Cover [Abstract] | |
| Entity Registrant Name | NUCOR CORP |
| Amendment Flag | false |
| Entity Central Index Key | 0000073309 |
| Document Type | 8-K |
| Document Period End Date | Dec. 17, 2020 |
| Entity Incorporation State Country Code | DE |
| Entity File Number | 1-4119 |
| Entity Tax Identification Number | 13-1860817 |
| Entity Address, Address Line One | 1915 Rexford Road |
| Entity Address, City or Town | Charlotte |
| Entity Address, State or Province | NC |
| Entity Address, Postal Zip Code | 28211 |
| City Area Code | (704) |
| Local Phone Number | 366-7000 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Security 12b Title | Common Stock, par value $0.40 per share |
| Trading Symbol | NUE |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
