| Cover | Feb. 21, 2020 |
| Cover page. | |
| Document Type | 8-K |
| Document Period End Date | Feb. 21, 2020 |
| Entity Registrant Name | MUELLER INDUSTRIES INC |
| Entity Central Index Key | 0000089439 |
| Amendment Flag | false |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 1-6770 |
| Entity Tax Identification Number | 25-0790410 |
| Entity Address, Address Line One | 150 Schilling Boulevard |
| Entity Address, Address Line Two | Suite 100 |
| Entity Address, City or Town | Collierville |
| Entity Address, State or Province | TN |
| Entity Address, Postal Zip Code | 38017 |
| City Area Code | (901) |
| Local Phone Number | 753-3200 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock |
| Trading Symbol | MLI |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
