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FINANCING ACTIVITIES - Narrative (Details) |  |  | 3 Months Ended | 12 Months Ended |  |  |  |  |  |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Jan. 09, 2023 | Feb. 28, 1997 USD ($) | Dec. 31, 2022 USD ($) aircraft | Dec. 31, 2022 USD ($) aircraft | Dec. 31, 2021 USD ($) $ / shares | Dec. 31, 2020 USD ($) | Jan. 01, 2022 USD ($) | Jul. 31, 2020 USD ($) | Jun. 08, 2020 USD ($) | May 04, 2020 USD ($) | May 01, 2020 USD ($) $ / shares | Feb. 29, 2020 USD ($) | Dec. 31, 2019 USD ($) | Nov. 30, 2017 USD ($) | Nov. 30, 2016 USD ($) | Oct. 03, 2007 USD ($) Mortgages
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Initial conversion price (in USD per share) | $ / shares |  |  |  |  | $ 38.48 |  |  |  |  |  |  |  |  |  |  |
Loss on extinguishment of debt |  |  |  | $ 193,000,000 | $ 28,000,000 | $ 0 |  |  |  |  |  |  |  |  |  |
Equity feature of partial extinguishment of convertible notes |  |  |  |  | (92,000,000) |  |  |  |  |  |  |  |  |  |  |
Long-term debt |  |  | $ 8,097,000,000 | 8,097,000,000 |  |  |  |  |  |  |  |  |  |  |  |
Decrease in AOCI |  |  | (10,687,000,000) | (10,687,000,000) | (10,414,000,000) | (8,876,000,000) |  |  |  |  |  |  | $ (9,832,000,000) |  |  |
Payments of long-term debt and finance lease obligations |  |  |  | 2,437,000,000 | 612,000,000 | 839,000,000 |  |  |  |  |  |  |  |  |  |
Minimum level of liquidity required |  |  | 1,500,000,000 | 1,500,000,000 |  |  |  |  |  |  |  |  |  |  |  |
Outstanding letters of credit |  |  | 162,000,000 | 162,000,000 |  |  |  |  |  |  |  |  |  |  |  |
Net book value of assets pledged as collateral for the Company's secured borrowings, primarily aircraft and engines |  |  | 2,000,000,000 | 2,000,000,000 |  |  |  |  |  |  |  |  |  |  |  |
Aircraft |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net book value of assets pledged as collateral for the Company's secured borrowings, primarily aircraft and engines |  |  | 296,000,000 | 296,000,000 |  |  |  |  |  |  |  |  |  |  |  |
Capital in excess of par value |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Equity feature of partial extinguishment of convertible notes |  |  |  |  | (92,000,000) |  |  |  |  |  |  |  |  |  |  |
Decrease in AOCI |  |  | (4,037,000,000) | (4,037,000,000) | (4,224,000,000) | (4,191,000,000) |  |  |  |  |  |  | $ (1,581,000,000) |  |  |
Cumulative Effect, Period of Adoption, Adjustment |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Decrease in AOCI |  |  |  |  | 245,000,000 | 0 |  |  |  |  |  |  |  |  |  |
Cumulative Effect, Period of Adoption, Adjustment | Capital in excess of par value |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Decrease in AOCI |  |  |  |  | 300,000,000 |  |  |  |  |  |  |  |  |  |  |
Revolving Credit Facility |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Credit outstanding |  |  | 0 | 0 | 0 |  |  |  |  |  |  |  |  |  |  |
Maximum borrowing capacity |  |  | $ 1,500,000,000 | $ 1,500,000,000 |  |  |  |  |  |  |  |  |  |  |  |
Convertible Notes |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Term (in years) |  |  |  | 5 years |  |  |  |  |  |  |  |  |  |  |  |
Effective interest rate (as a percent) |  |  | 1.90% | 1.90% |  |  |  |  |  |  |  |  |  |  |  |
Accrued Interest |  |  |  | $ 34,000,000 | 110,000,000 |  |  |  |  |  |  |  |  |  |  |
Non-cash amortization of the debt discount |  |  |  | 0 | 73,000,000 |  |  |  |  |  |  |  |  |  |  |
Non-cash amortization of debt issuance costs |  |  |  | 12,000,000 | 9,000,000 |  |  |  |  |  |  |  |  |  |  |
Convertible Notes | Accounting Standards Update 2020-06 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  |  |  | $ 300,000,000 |  |  |  |  |  |  |  |  |
Convertible Notes | Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2020-06 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Interest rate stated in the debt agreement (as a percent) |  |  |  |  |  |  | 1.25% |  |  |  |  |  |  |  |  |
Convertible Notes | Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2020-06 | Capital in excess of par value |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Decrease in AOCI |  |  |  |  |  |  | $ 300,000,000 |  |  |  |  |  |  |  |  |
Convertible Debt And Unsecured Debt |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accrued Interest |  |  |  | 28,000,000 |  |  |  |  |  |  |  |  |  |  |  |
Payments of long-term debt and finance lease obligations |  |  |  | 3,100,000,000 | 905,000,000 |  |  |  |  |  |  |  |  |  |  |
Principal repayment |  |  |  | 2,256,000,000 |  |  |  |  |  |  |  |  |  |  |  |
Line of Credit |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Maximum borrowing capacity |  |  | $ 1,000,000,000 | $ 1,000,000,000 |  |  |  |  |  |  |  |  |  |  |  |
Total 5.125 Notes due 2027 | Unsecured Debt |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Principal amount |  |  |  |  |  | $ 2,000,000,000 |  |  |  |  |  |  |  |  |  |
5.125 Unsecured Notes due 2027 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Face amount of debt |  |  |  |  |  |  |  |  | $ 1,300,000,000 |  |  |  |  |  |  |
Term (in years) |  |  |  |  |  | 364 days |  |  |  |  |  |  |  |  |  |
5.125% Notes due 2027 | Unsecured Debt |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Interest rate stated in the debt agreement (as a percent) |  |  | 5.125% | 5.125% |  | 5.125% |  |  |  |  |  |  |  |  |  |
Principal amount |  |  | $ 1,727,000,000 | $ 1,727,000,000 | 2,000,000,000 |  |  | $ 700,000,000 |  |  |  |  |  |  |  |
Accrued Interest |  |  |  | 4,000,000 |  |  |  |  |  |  |  |  |  |  |  |
Principal repayment |  |  |  | $ 272,000,000 |  |  |  |  |  |  |  |  |  |  |  |
5.25% Notes due 2025 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Face amount of debt |  |  |  |  |  | $ 1,550,000,000 |  |  |  | $ 1,250,000,000 |  |  |  |  |  |
Term (in years) |  |  |  |  |  | 364 days |  |  |  |  |  |  |  |  |  |
5.25% Notes due 2025 | Unsecured Debt |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Interest rate stated in the debt agreement (as a percent) |  |  | 5.25% | 5.25% |  | 5.25% |  |  |  |  |  |  |  |  |  |
Principal amount |  |  | $ 1,302,000,000 | $ 1,302,000,000 | 1,550,000,000 |  |  | $ 300,000,000 |  |  |  |  |  |  |  |
Accrued Interest |  |  |  | 4,000,000 |  |  |  |  |  |  |  |  |  |  |  |
Principal repayment |  |  |  | $ 248,000,000 |  |  |  |  |  |  |  |  |  |  |  |
4.75% Notes due 2023 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Face amount of debt |  |  |  |  |  | $ 1,250,000,000 |  |  | $ 500,000,000 | $ 750,000,000 |  |  |  |  |  |
Interest rate stated in the debt agreement (as a percent) |  |  |  |  |  |  |  |  |  | 4.75% |  |  |  |  |  |
Term (in years) |  |  |  |  |  | 364 days |  |  |  |  |  |  |  |  |  |
4.75% Notes due 2023 | Unsecured Debt |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Interest rate stated in the debt agreement (as a percent) |  |  | 4.75% | 4.75% |  |  |  |  |  |  |  |  |  |  |  |
Principal amount |  |  | $ 0 | $ 0 | 1,250,000,000 |  |  |  |  |  |  |  |  |  |  |
Accrued Interest |  |  |  | 19,000,000 |  |  |  |  |  |  |  |  |  |  |  |
Principal repayment |  |  |  | $ 1,250,000,000 |  |  |  |  |  |  |  |  |  |  |  |
Amended 364-Day Term Loan Credit Facility |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Aircrafts secured to debt transactions | aircraft |  |  | 83 | 83 |  |  |  |  |  |  |  |  |  |  |  |
Amended 364-Day Term Loan Credit Facility | LIBOR |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Interest rate stated in the debt agreement (as a percent) |  |  | 100.00% | 100.00% |  |  |  |  |  |  |  |  |  |  |  |
Amended 364-Day Term Loan Credit Facility | LIBOR | Minimum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Interest rate stated in the debt agreement (as a percent) |  |  | 100.00% | 100.00% |  |  |  |  |  |  |  |  |  |  |  |
Amended 364-Day Term Loan Credit Facility | New York Fed Bank Rate |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Interest rate stated in the debt agreement (as a percent) |  |  | 50.00% | 50.00% |  |  |  |  |  |  |  |  |  |  |  |
Amended 364-Day Term Loan Credit Facility | Base Rate | Minimum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Interest rate stated in the debt agreement (as a percent) |  |  | 100.00% | 100.00% |  |  |  |  |  |  |  |  |  |  |  |
Amended 364-Day Term Loan Credit Facility | Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Interest rate stated in the debt agreement (as a percent) |  |  | 10.00% | 10.00% |  |  |  |  |  |  |  |  |  |  |  |
2.625% Notes due 2030 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Face amount of debt |  |  |  |  |  |  |  |  |  |  |  | $ 500,000,000 |  |  |  |
2.625% Notes due 2030 | Unsecured Debt |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Interest rate stated in the debt agreement (as a percent) |  |  |  |  |  |  |  |  |  |  |  | 2.625% |  |  |  |
Principal amount |  |  | $ 500,000,000 | $ 500,000,000 | 500,000,000 |  |  |  |  |  |  |  |  |  |  |
2.75% Notes due 2022 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Face amount of debt |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 300,000,000 |  |
Interest rate stated in the debt agreement (as a percent) |  |  |  |  |  |  |  |  |  |  |  |  |  | 2.75% |  |
2.75% Notes due 2022 | Unsecured Debt |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Interest rate stated in the debt agreement (as a percent) |  |  | 2.75% | 2.75% |  |  |  |  |  |  |  |  |  |  |  |
Principal amount |  |  | $ 0 | $ 0 | 300,000,000 |  |  |  |  |  |  |  |  |  |  |
Pass Through Certificates due 2022 - 6.24% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Face amount of debt |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 500,000,000
Number of mortgages on secured aircraft | Mortgages |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 16
Pass Through Certificates Series A |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Face amount of debt |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 412,000,000
Interest rate stated in the debt agreement (as a percent) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 6.15%
Pass Through Certificates Series B |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Face amount of debt |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 88,000,000
Interest rate stated in the debt agreement (as a percent) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 6.65%
7.375% Debentures due 2027 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Face amount of debt |  | $ 100,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Interest rate stated in the debt agreement (as a percent) |  | 7.375% |  |  |  |  |  |  |  |  |  |  |  |  |  |
7.375% Debentures due 2027 | Unsecured Debt |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Interest rate stated in the debt agreement (as a percent) |  |  | 7.375% | 7.375% |  |  |  |  |  |  |  |  |  |  |  |
Principal amount |  |  | $ 114,000,000 | $ 114,000,000 | 116,000,000 |  |  |  |  |  |  |  |  |  |  |
1.25% Convertible Notes due 2025 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Conversion ratio (in shares) |  |  | 0.0259909 |  |  |  |  |  |  |  |  |  |  |  |  |
Initial conversion price (in USD per share) | $ / shares |  |  |  |  |  |  |  |  |  |  | $ 38.48 |  |  |  |  |
If-converted value exceeded principal amount |  |  |  | $ 201,000,000 |  |  |  |  |  |  |  |  |  |  |  |
1.25% Convertible Notes due 2025 | Subsequent Event |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Conversion ratio (in shares) | 0.0261250 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
1.25% Convertible Notes due 2025 | Unsecured Debt |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Interest rate stated in the debt agreement (as a percent) |  |  | 1.25% | 1.25% |  |  |  |  |  |  |  |  |  |  |  |
1.25% Convertible Notes due 2025 | Convertible Notes |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Face amount of debt |  |  |  |  |  |  |  |  |  |  | $ 2,300,000,000 |  |  |  |  |
Interest rate stated in the debt agreement (as a percent) |  |  |  |  |  |  |  |  |  |  | 1.25% |  |  |  |  |
Principal amount |  |  | $ 1,611,000,000 | $ 1,611,000,000 | 1,842,000,000 |  |  |  |  |  |  |  |  |  |  |
Accrued Interest |  |  |  | 1,000,000 | 92,000,000 |  |  |  |  |  |  |  |  |  |  |
Principal repayment |  |  |  | $ 486,000,000 | 203,000,000 |  |  |  |  |  |  |  |  |  |  |
Unsecured Senior Notes Due 2027 - 3.45% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Face amount of debt |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 300,000,000 |  |
Interest rate stated in the debt agreement (as a percent) |  |  |  |  |  |  |  |  |  |  |  |  |  | 3.45% |  |
Unsecured Senior Notes Due 2027 - 3.45% | Treasury Rate |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Spread on variable rate (as a percent) |  | 0.20% |  |  |  |  |  |  |  |  |  |  |  |  |  |
3.00% Notes due 2026 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Face amount of debt |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 300,000,000 |
Interest rate stated in the debt agreement (as a percent) |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 3.00% |
3.00% Notes due 2026 | Unsecured Debt |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Interest rate stated in the debt agreement (as a percent) |  |  | 3.00% | 3.00% |  |  |  |  |  |  |  |  |  |  |  |
Principal amount |  |  | $ 300,000,000 | $ 300,000,000 | $ 300,000,000 |  |  |  |  |  |  |  |  |  |  |

X
- Definition Aircraft Subject to Secure Debt Transactions + References No definition available. + Details
Name: | luv_AircraftSubjectToSecureDebtTransactions
Namespace Prefix: | luv_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number of Mortgages on Secured Aircraft + References No definition available. + Details
Name: | luv_NumberofMortgagesonSecuredAircraft
Namespace Prefix: | luv_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

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- Definition Repayments Of Other Long-Term Debt And Finance Lease Obligations + References No definition available. + Details
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