| Document and Entity Information Document | Jul. 23, 2020 |
| Entity Information [Line Items] | |
| Entity Central Index Key | 0000092380 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Amendment Flag | false |
| Entity Emerging Growth Company | false |
| City Area Code | 214 |
| Local Phone Number | 792-4000 |
| Entity Registrant Name | SOUTHWEST AIRLINES CO. |
| Entity Address, Address Line One | P. O. Box 36611 |
| Entity Address, Postal Zip Code | 75235-1611 |
| Entity Incorporation, State or Country Code | TX |
| Document Type | 8-K |
| Document Period End Date | Jul. 23, 2020 |
| Entity Registrant Name | SOUTHWEST AIRLINES CO. |
| Entity File Number | 1-7259 |
| Entity Tax Identification Number | 74-1563240 |
| Entity Address, City or Town | Dallas, |
| Entity Address, State or Province | TX |
| NEW YORK STOCK EXCHANGE, INC. [Member] | |
| Entity Information [Line Items] | |
| Title of 12(b) Security | Common Stock ($1.00 par value) |
| Trading Symbol | LUV |
| Security Exchange Name | NYSE |
