| Document and Entity Information | Jul. 08, 2021 |
| Cover [Abstract] | |
| Entity Registrant Name | LENNOX INTERNATIONAL INC |
| Amendment Flag | false |
| Entity Central Index Key | 0001069202 |
| Document Type | 8-K |
| Document Period End Date | Jul. 8, 2021 |
| Entity Incorporation State Country Code | DE |
| Entity File Number | 001-15149 |
| Entity Tax Identification Number | 42-0991521 |
| Entity Address, Address Line One | 2140 Lake Park Blvd. |
| Entity Address, City or Town | Richardson |
| Entity Address, State or Province | TX |
| Entity Address, Postal Zip Code | 75080 |
| City Area Code | (972) |
| Local Phone Number | 497-5000 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Security 12b Title | Common Stock, par value $0.01 per share |
| Trading Symbol | LII |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
