XML 12 R39.htm IDEA: XBRL DOCUMENT v2.4.1.9
Fair Value Measurements - Measured on Recurring Basis (Details) (USD $)
In Millions, unless otherwise specified
3 Months Ended
Mar. 31, 2015
Dec. 31, 2012
Dec. 31, 2014
Fuel derivatives:      
Derivative Asset, Fair Value, Gross Asset $ 1,244us-gaap_DerivativeFairValueOfDerivativeAsset [1]   $ 1,360us-gaap_DerivativeFairValueOfDerivativeAsset [1]
Fuel derivatives:      
Derivative Liability, Fair Value, Gross Liability (2,367)us-gaap_DerivativeFairValueOfDerivativeLiability [1]   (2,409)us-gaap_DerivativeFairValueOfDerivativeLiability [1]
Fair Value, Assets, Level 1 to Level 2 Transfers, Amount 0us-gaap_FairValueAssetsLevel1ToLevel2TransfersAmount   0us-gaap_FairValueAssetsLevel1ToLevel2TransfersAmount
Fair Value, Liabilities, Level 1 to Level 2 Transfers, Amount 0us-gaap_FairValueLiabilitiesLevel1ToLevel2TransfersAmount   0us-gaap_FairValueLiabilitiesLevel1ToLevel2TransfersAmount
Fair Value, Assets, Level 2 to Level 1 Transfers, Amount 0us-gaap_FairValueAssetsLevel2ToLevel1TransfersAmount   0us-gaap_FairValueAssetsLevel2ToLevel1TransfersAmount
Fair Value, Liabilities, Level 2 to Level 1 Transfers, Amount 0us-gaap_FairValueLiabilitiesLevel2ToLevel1TransfersAmount   0us-gaap_FairValueLiabilitiesLevel2ToLevel1TransfersAmount
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers, Net 0us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersNet 0us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersNet  
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Transfers, Net 0us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityTransfersNet 0us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityTransfersNet  
Fair Value, Measurements, Recurring | Period end date      
Assets      
Treasury bills 1,150us-gaap_FinancialInstrumentsOwnedUSGovernmentAndAgencyObligationsAtFairValue
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
  1,450us-gaap_FinancialInstrumentsOwnedUSGovernmentAndAgencyObligationsAtFairValue
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
Interest rate derivatives 4us-gaap_InterestRateDerivativeAssetsAtFairValue
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
  13us-gaap_InterestRateDerivativeAssetsAtFairValue
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
Other available for sale securities 61us-gaap_OtherAssetsFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
  68us-gaap_OtherAssetsFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
Total assets 4,770us-gaap_AssetsFairValueDisclosureRecurring
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
  4,443us-gaap_AssetsFairValueDisclosureRecurring
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
Liabilities      
Interest rate derivatives (61)us-gaap_InterestRateDerivativeLiabilitiesAtFairValue
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
  (61)us-gaap_InterestRateDerivativeLiabilitiesAtFairValue
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
Total Liabilities (2,367)us-gaap_LiabilitiesFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
  (2,409)us-gaap_LiabilitiesFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
Fair Value, Measurements, Recurring | Quoted prices in active markets for identical assets (Level 1)      
Assets      
Treasury bills 1,150us-gaap_FinancialInstrumentsOwnedUSGovernmentAndAgencyObligationsAtFairValue
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
  1,450us-gaap_FinancialInstrumentsOwnedUSGovernmentAndAgencyObligationsAtFairValue
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
Interest rate derivatives 0us-gaap_InterestRateDerivativeAssetsAtFairValue
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
  0us-gaap_InterestRateDerivativeAssetsAtFairValue
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
Other available for sale securities 61us-gaap_OtherAssetsFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
  63us-gaap_OtherAssetsFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
Total assets 3,102us-gaap_AssetsFairValueDisclosureRecurring
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
  2,623us-gaap_AssetsFairValueDisclosureRecurring
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
Liabilities      
Interest rate derivatives 0us-gaap_InterestRateDerivativeLiabilitiesAtFairValue
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
  0us-gaap_InterestRateDerivativeLiabilitiesAtFairValue
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
Total Liabilities 0us-gaap_LiabilitiesFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
  0us-gaap_LiabilitiesFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
Fair Value, Measurements, Recurring | Significant other observable inputs (Level 2)      
Assets      
Treasury bills 0us-gaap_FinancialInstrumentsOwnedUSGovernmentAndAgencyObligationsAtFairValue
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
  0us-gaap_FinancialInstrumentsOwnedUSGovernmentAndAgencyObligationsAtFairValue
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
Interest rate derivatives 4us-gaap_InterestRateDerivativeAssetsAtFairValue
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
  13us-gaap_InterestRateDerivativeAssetsAtFairValue
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
Other available for sale securities 0us-gaap_OtherAssetsFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
  0us-gaap_OtherAssetsFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
Total assets 916us-gaap_AssetsFairValueDisclosureRecurring
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
  896us-gaap_AssetsFairValueDisclosureRecurring
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
Liabilities      
Interest rate derivatives (61)us-gaap_InterestRateDerivativeLiabilitiesAtFairValue
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
  (61)us-gaap_InterestRateDerivativeLiabilitiesAtFairValue
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
Total Liabilities (397)us-gaap_LiabilitiesFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
  (426)us-gaap_LiabilitiesFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
Fair Value, Measurements, Recurring | Significant unobservable inputs (Level 3)      
Assets      
Treasury bills 0us-gaap_FinancialInstrumentsOwnedUSGovernmentAndAgencyObligationsAtFairValue
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
  0us-gaap_FinancialInstrumentsOwnedUSGovernmentAndAgencyObligationsAtFairValue
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
Interest rate derivatives 0us-gaap_InterestRateDerivativeAssetsAtFairValue
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
  0us-gaap_InterestRateDerivativeAssetsAtFairValue
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
Other available for sale securities 0us-gaap_OtherAssetsFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
  5us-gaap_OtherAssetsFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
Total assets 752us-gaap_AssetsFairValueDisclosureRecurring
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
  924us-gaap_AssetsFairValueDisclosureRecurring
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
Liabilities      
Interest rate derivatives 0us-gaap_InterestRateDerivativeLiabilitiesAtFairValue
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
  0us-gaap_InterestRateDerivativeLiabilitiesAtFairValue
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
Total Liabilities (1,970)us-gaap_LiabilitiesFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
  (1,983)us-gaap_LiabilitiesFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
Cash Equivalents | Fair Value, Measurements, Recurring | Period end date      
Assets      
Cash equivalents 1,891us-gaap_CashAndCashEquivalentsFairValueDisclosure
/ luv_FairValueByFairValueAssetDescriptionAxis
= us-gaap_CashEquivalentsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
[2]   1,110us-gaap_CashAndCashEquivalentsFairValueDisclosure
/ luv_FairValueByFairValueAssetDescriptionAxis
= us-gaap_CashEquivalentsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
[2]
Cash Equivalents | Fair Value, Measurements, Recurring | Quoted prices in active markets for identical assets (Level 1)      
Assets      
Cash equivalents 1,891us-gaap_CashAndCashEquivalentsFairValueDisclosure
/ luv_FairValueByFairValueAssetDescriptionAxis
= us-gaap_CashEquivalentsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
[2]   1,110us-gaap_CashAndCashEquivalentsFairValueDisclosure
/ luv_FairValueByFairValueAssetDescriptionAxis
= us-gaap_CashEquivalentsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
[2]
Cash Equivalents | Fair Value, Measurements, Recurring | Significant other observable inputs (Level 2)      
Assets      
Cash equivalents 0us-gaap_CashAndCashEquivalentsFairValueDisclosure
/ luv_FairValueByFairValueAssetDescriptionAxis
= us-gaap_CashEquivalentsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
[2]   0us-gaap_CashAndCashEquivalentsFairValueDisclosure
/ luv_FairValueByFairValueAssetDescriptionAxis
= us-gaap_CashEquivalentsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
[2]
Cash Equivalents | Fair Value, Measurements, Recurring | Significant unobservable inputs (Level 3)      
Assets      
Cash equivalents 0us-gaap_CashAndCashEquivalentsFairValueDisclosure
/ luv_FairValueByFairValueAssetDescriptionAxis
= us-gaap_CashEquivalentsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
[2]   0us-gaap_CashAndCashEquivalentsFairValueDisclosure
/ luv_FairValueByFairValueAssetDescriptionAxis
= us-gaap_CashEquivalentsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
[2]
Commercial paper | Fair Value, Measurements, Recurring | Period end date      
Assets      
Cash equivalents     70us-gaap_CashAndCashEquivalentsFairValueDisclosure
/ luv_FairValueByFairValueAssetDescriptionAxis
= us-gaap_CommercialPaperMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
Commercial paper | Fair Value, Measurements, Recurring | Quoted prices in active markets for identical assets (Level 1)      
Assets      
Cash equivalents     0us-gaap_CashAndCashEquivalentsFairValueDisclosure
/ luv_FairValueByFairValueAssetDescriptionAxis
= us-gaap_CommercialPaperMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
Commercial paper | Fair Value, Measurements, Recurring | Significant other observable inputs (Level 2)      
Assets      
Cash equivalents     70us-gaap_CashAndCashEquivalentsFairValueDisclosure
/ luv_FairValueByFairValueAssetDescriptionAxis
= us-gaap_CommercialPaperMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
Commercial paper | Fair Value, Measurements, Recurring | Significant unobservable inputs (Level 3)      
Assets      
Cash equivalents     0us-gaap_CashAndCashEquivalentsFairValueDisclosure
/ luv_FairValueByFairValueAssetDescriptionAxis
= us-gaap_CommercialPaperMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
Certificates of deposit | Fair Value, Measurements, Recurring | Period end date      
Assets      
Cash equivalents 18us-gaap_CashAndCashEquivalentsFairValueDisclosure
/ luv_FairValueByFairValueAssetDescriptionAxis
= us-gaap_CertificatesOfDepositMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
  4us-gaap_CashAndCashEquivalentsFairValueDisclosure
/ luv_FairValueByFairValueAssetDescriptionAxis
= us-gaap_CertificatesOfDepositMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
Certificates of deposit | Fair Value, Measurements, Recurring | Quoted prices in active markets for identical assets (Level 1)      
Assets      
Cash equivalents 0us-gaap_CashAndCashEquivalentsFairValueDisclosure
/ luv_FairValueByFairValueAssetDescriptionAxis
= us-gaap_CertificatesOfDepositMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
  0us-gaap_CashAndCashEquivalentsFairValueDisclosure
/ luv_FairValueByFairValueAssetDescriptionAxis
= us-gaap_CertificatesOfDepositMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
Certificates of deposit | Fair Value, Measurements, Recurring | Significant other observable inputs (Level 2)      
Assets      
Cash equivalents 18us-gaap_CashAndCashEquivalentsFairValueDisclosure
/ luv_FairValueByFairValueAssetDescriptionAxis
= us-gaap_CertificatesOfDepositMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
  4us-gaap_CashAndCashEquivalentsFairValueDisclosure
/ luv_FairValueByFairValueAssetDescriptionAxis
= us-gaap_CertificatesOfDepositMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
Certificates of deposit | Fair Value, Measurements, Recurring | Significant unobservable inputs (Level 3)      
Assets      
Cash equivalents 0us-gaap_CashAndCashEquivalentsFairValueDisclosure
/ luv_FairValueByFairValueAssetDescriptionAxis
= us-gaap_CertificatesOfDepositMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
  0us-gaap_CashAndCashEquivalentsFairValueDisclosure
/ luv_FairValueByFairValueAssetDescriptionAxis
= us-gaap_CertificatesOfDepositMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
Eurodollar time deposits | Fair Value, Measurements, Recurring | Period end date      
Assets      
Cash equivalents 116us-gaap_CashAndCashEquivalentsFairValueDisclosure
/ luv_FairValueByFairValueAssetDescriptionAxis
= us-gaap_EuroDollarCertificatesOfDepositMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
  98us-gaap_CashAndCashEquivalentsFairValueDisclosure
/ luv_FairValueByFairValueAssetDescriptionAxis
= us-gaap_EuroDollarCertificatesOfDepositMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
Eurodollar time deposits | Fair Value, Measurements, Recurring | Quoted prices in active markets for identical assets (Level 1)      
Assets      
Cash equivalents 0us-gaap_CashAndCashEquivalentsFairValueDisclosure
/ luv_FairValueByFairValueAssetDescriptionAxis
= us-gaap_EuroDollarCertificatesOfDepositMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
  0us-gaap_CashAndCashEquivalentsFairValueDisclosure
/ luv_FairValueByFairValueAssetDescriptionAxis
= us-gaap_EuroDollarCertificatesOfDepositMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
Eurodollar time deposits | Fair Value, Measurements, Recurring | Significant other observable inputs (Level 2)      
Assets      
Cash equivalents 116us-gaap_CashAndCashEquivalentsFairValueDisclosure
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Eurodollar time deposits | Fair Value, Measurements, Recurring | Significant unobservable inputs (Level 3)      
Assets      
Cash equivalents 0us-gaap_CashAndCashEquivalentsFairValueDisclosure
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Assets      
Investments 263us-gaap_InvestmentsFairValueDisclosure
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Certificates of deposit | Fair Value, Measurements, Recurring | Quoted prices in active markets for identical assets (Level 1)      
Assets      
Investments 0us-gaap_InvestmentsFairValueDisclosure
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Certificates of deposit | Fair Value, Measurements, Recurring | Significant other observable inputs (Level 2)      
Assets      
Investments 263us-gaap_InvestmentsFairValueDisclosure
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Certificates of deposit | Fair Value, Measurements, Recurring | Significant unobservable inputs (Level 3)      
Assets      
Investments 0us-gaap_InvestmentsFairValueDisclosure
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Assets      
Investments 27us-gaap_InvestmentsFairValueDisclosure
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Assets      
Investments 0us-gaap_InvestmentsFairValueDisclosure
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Auction rate securities | Fair Value, Measurements, Recurring | Significant other observable inputs (Level 2)      
Assets      
Investments 0us-gaap_InvestmentsFairValueDisclosure
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Auction rate securities | Fair Value, Measurements, Recurring | Significant unobservable inputs (Level 3)      
Assets      
Investments 27us-gaap_InvestmentsFairValueDisclosure
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[3]
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Fuel derivatives:      
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[4]
Fuel derivatives:      
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[4]
Swap | Fair Value, Measurements, Recurring | Quoted prices in active markets for identical assets (Level 1)      
Fuel derivatives:      
Derivative Asset, Fair Value, Gross Asset 0us-gaap_DerivativeFairValueOfDerivativeAsset
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[4]
Fuel derivatives:      
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[4]
Swap | Fair Value, Measurements, Recurring | Significant other observable inputs (Level 2)      
Fuel derivatives:      
Derivative Asset, Fair Value, Gross Asset 515us-gaap_DerivativeFairValueOfDerivativeAsset
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[4]
Fuel derivatives:      
Derivative Asset, Fair Value, Gross Liability (336)us-gaap_DerivativeAssetFairValueGrossLiability
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[4]
Swap | Fair Value, Measurements, Recurring | Significant unobservable inputs (Level 3)      
Fuel derivatives:      
Derivative Asset, Fair Value, Gross Asset 0us-gaap_DerivativeFairValueOfDerivativeAsset
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[4]
Fuel derivatives:      
Derivative Asset, Fair Value, Gross Liability 0us-gaap_DerivativeAssetFairValueGrossLiability
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[4]
Options Held | Fair Value, Measurements, Recurring | Period end date      
Fuel derivatives:      
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[4]
Fuel derivatives:      
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[4]
Options Held | Fair Value, Measurements, Recurring | Quoted prices in active markets for identical assets (Level 1)      
Fuel derivatives:      
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[4]
Fuel derivatives:      
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[4]
Options Held | Fair Value, Measurements, Recurring | Significant other observable inputs (Level 2)      
Fuel derivatives:      
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[4]
Fuel derivatives:      
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[4]
Options Held | Fair Value, Measurements, Recurring | Significant unobservable inputs (Level 3)      
Fuel derivatives:      
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[4]
Fuel derivatives:      
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[4]
[1] Represents the position of each trade before consideration of offsetting positions with each counterparty and does not include the impact of cash collateral deposits provided to or received from counterparties. See discussion of credit risk and collateral following in this Note.
[2] Cash equivalents are primarily composed of money market investments.
[3] Noncurrent investments are included in Other assets in the unaudited Condensed Consolidated Balance Sheet.
[4] In the unaudited Condensed Consolidated Balance Sheet amounts are presented as a net liability.