XML 20 R57.htm IDEA: XBRL DOCUMENT
v3.19.3

Fair Value Measurements - Quantitative Information about Level 3 Fair Value (Details) - Significant unobservable inputs (Level 3) - Fuel derivatives - Measurement Input, Option Volatility | Sep. 30, 2019
--- | ---
Minimum | Fourth quarter 2019 |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |
Derivative Asset, Measurement Input | 0.22
Minimum | 2020 |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |
Derivative Asset, Measurement Input | 0.24
Minimum | 2021 |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |
Derivative Asset, Measurement Input | 0.20
Minimum | 2022 |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |
Derivative Asset, Measurement Input | 0.19
Maximum | Fourth quarter 2019 |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |
Derivative Asset, Measurement Input | 0.38
Maximum | 2020 |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |
Derivative Asset, Measurement Input | 0.42
Maximum | 2021 |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |
Derivative Asset, Measurement Input | 0.29
Maximum | 2022 |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |
Derivative Asset, Measurement Input | 0.21

X
- Definition Value of input used to measure derivative asset. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (bbb)(2) -URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258 + Details
Name: | us-gaap_DerivativeAssetMeasurementInput
Namespace Prefix: | us-gaap_
Data Type: | xbrli:decimalItemType
Balance Type: | na
Period Type: | instant

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | srt_RangeAxis=srt_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=us-gaap_CommodityContractMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputOptionVolatilityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | luv_PeriodAxis=luv_FourthQuarterCYMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | luv_PeriodAxis=luv_NextYearMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | luv_PeriodAxis=luv_YearTwoMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | luv_PeriodAxis=luv_YearThreeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |