| Document and Entity Information | Feb. 08, 2021 |
| Cover [Abstract] | |
| Entity Registrant Name | LEGGETT & PLATT INC |
| Amendment Flag | false |
| Entity Central Index Key | 0000058492 |
| Document Type | 8-K |
| Document Period End Date | Feb. 8, 2021 |
| Entity Incorporation State Country Code | MO |
| Entity File Number | 001-07845 |
| Entity Tax Identification Number | 44-0324630 |
| Entity Address, Address Line One | No. 1 Leggett Road |
| Entity Address, City or Town | Carthage |
| Entity Address, State or Province | MO |
| Entity Address, Postal Zip Code | 64836 |
| City Area Code | 417 |
| Local Phone Number | 358-8131 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Security 12b Title | Common Stock, $.01 par value |
| Trading Symbol | LEG |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
