XML 62 R47.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Fair Value Measurements - Measured on Recurring Basis (Details) - USD ($) $ in Millions | Mar. 31, 2018 | Dec. 31, 2017
--- | --- | ---
Fuel derivatives: |  |  |  |  |
Derivative Asset, Fair Value, Gross Asset | [1] | $ 363 |  | $ 283 |
Fuel derivatives: |  |  |  |  |
Derivative Liability, Fair Value, Gross Liability | [1] | (48) |  | (57) |
Fair Value, Measurements, Recurring | Quoted prices in active markets for identical assets (Level 1) |  |  |  |  |
Assets |  |  |  |  |
Treasury bills |  | 1,144 |  | 1,491 |
Fuel derivatives: |  |  |  |  |
Other available for sale securities |  | 122 |  | 107 |
Total assets |  | 2,766 |  | 2,731 |
Liabilities |  |  |  |  |
Interest rate derivatives (see Note 3) |  | 0 |  | 0 |
Total Liabilities |  | 0 |  | 0 |
Fair Value, Measurements, Recurring | Significant other observable inputs (Level 2) |  |  |  |  |
Assets |  |  |  |  |
Treasury bills |  | 0 |  | 0 |
Fuel derivatives: |  |  |  |  |
Other available for sale securities |  | 0 |  | 0 |
Total assets |  | 599 |  | 649 |
Liabilities |  |  |  |  |
Interest rate derivatives (see Note 3) |  | (25) |  | (22) |
Total Liabilities |  | (25) |  | (22) |
Fair Value, Measurements, Recurring | Significant unobservable inputs (Level 3) |  |  |  |  |
Assets |  |  |  |  |
Treasury bills |  | 0 |  | 0 |
Fuel derivatives: |  |  |  |  |
Other available for sale securities |  | 0 |  | 0 |
Total assets |  | 363 |  | 283 |
Liabilities |  |  |  |  |
Interest rate derivatives (see Note 3) |  | 0 |  | 0 |
Total Liabilities |  | (23) |  | (35) |
Cash Equivalents | Fair Value, Measurements, Recurring | Quoted prices in active markets for identical assets (Level 1) |  |  |  |  |
Assets |  |  |  |  |
Cash equivalents |  | 1,500 | [2] | 1,133 | [3]
Cash Equivalents | Fair Value, Measurements, Recurring | Significant other observable inputs (Level 2) |  |  |  |  |
Assets |  |  |  |  |
Cash equivalents |  | 0 | [2] | 0 | [3]
Cash Equivalents | Fair Value, Measurements, Recurring | Significant unobservable inputs (Level 3) |  |  |  |  |
Assets |  |  |  |  |
Cash equivalents |  | 0 | [2] | 0 | [3]
Commercial paper | Fair Value, Measurements, Recurring | Quoted prices in active markets for identical assets (Level 1) |  |  |  |  |
Assets |  |  |  |  |
Cash equivalents |  | 0 |  | 0 |
Commercial paper | Fair Value, Measurements, Recurring | Significant other observable inputs (Level 2) |  |  |  |  |
Assets |  |  |  |  |
Cash equivalents |  | 285 |  | 350 |
Commercial paper | Fair Value, Measurements, Recurring | Significant unobservable inputs (Level 3) |  |  |  |  |
Assets |  |  |  |  |
Cash equivalents |  | 0 |  | 0 |
Certificates of deposit | Fair Value, Measurements, Recurring | Quoted prices in active markets for identical assets (Level 1) |  |  |  |  |
Assets |  |  |  |  |
Cash equivalents |  | 0 |  | 0 |
Investments |  | 0 |  | 0 |
Certificates of deposit | Fair Value, Measurements, Recurring | Significant other observable inputs (Level 2) |  |  |  |  |
Assets |  |  |  |  |
Cash equivalents |  | 12 |  | 12 |
Investments |  | 277 |  | 287 |
Certificates of deposit | Fair Value, Measurements, Recurring | Significant unobservable inputs (Level 3) |  |  |  |  |
Assets |  |  |  |  |
Cash equivalents |  | 0 |  | 0 |
Investments |  | 0 |  | 0 |
Time Deposits | Fair Value, Measurements, Recurring | Quoted prices in active markets for identical assets (Level 1) |  |  |  |  |
Assets |  |  |  |  |
Cash equivalents |  | 0 |  |  |
Time Deposits | Fair Value, Measurements, Recurring | Significant other observable inputs (Level 2) |  |  |  |  |
Assets |  |  |  |  |
Cash equivalents |  | 25 |  |  |
Time Deposits | Fair Value, Measurements, Recurring | Significant unobservable inputs (Level 3) |  |  |  |  |
Assets |  |  |  |  |
Cash equivalents |  | 0 |  |  |
Options Held | Fair Value, Measurements, Recurring | Quoted prices in active markets for identical assets (Level 1) |  |  |  |  |
Fuel derivatives: |  |  |  |  |
Derivative Asset, Fair Value, Gross Asset |  | 0 | [4] | 0 | [5]
Fuel derivatives: |  |  |  |  |
Derivative Asset, Fair Value, Gross Liability |  | 0 | [4] | 0 | [5]
Options Held | Fair Value, Measurements, Recurring | Significant other observable inputs (Level 2) |  |  |  |  |
Fuel derivatives: |  |  |  |  |
Derivative Asset, Fair Value, Gross Asset |  | 0 | [4] | 0 | [5]
Fuel derivatives: |  |  |  |  |
Derivative Asset, Fair Value, Gross Liability |  | 0 | [4] | 0 | [5]
Options Held | Fair Value, Measurements, Recurring | Significant unobservable inputs (Level 3) |  |  |  |  |
Fuel derivatives: |  |  |  |  |
Derivative Asset, Fair Value, Gross Asset |  | 363 | [4] | 283 | [5]
Fuel derivatives: |  |  |  |  |
Derivative Asset, Fair Value, Gross Liability |  | (23) | [4] | (35) | [5]
Estimate of Fair Value Measurement [Member] | Fair Value, Measurements, Recurring |  |  |  |  |
Assets |  |  |  |  |
Treasury bills |  | 1,144 |  | 1,491 |
Fuel derivatives: |  |  |  |  |
Other available for sale securities |  | 122 |  | 107 |
Total assets |  | 3,728 |  | 3,663 |
Liabilities |  |  |  |  |
Interest rate derivatives (see Note 3) |  | (25) |  | (22) |
Total Liabilities |  | (48) |  | (57) |
Estimate of Fair Value Measurement [Member] | Cash Equivalents | Fair Value, Measurements, Recurring |  |  |  |  |
Assets |  |  |  |  |
Cash equivalents |  | 1,500 | [2] | 1,133 | [3]
Estimate of Fair Value Measurement [Member] | Commercial paper | Fair Value, Measurements, Recurring |  |  |  |  |
Assets |  |  |  |  |
Cash equivalents |  | 285 |  | 350 |
Estimate of Fair Value Measurement [Member] | Certificates of deposit | Fair Value, Measurements, Recurring |  |  |  |  |
Assets |  |  |  |  |
Cash equivalents |  | 12 |  | 12 |
Investments |  | 277 |  | 287 |
Estimate of Fair Value Measurement [Member] | Time Deposits | Fair Value, Measurements, Recurring |  |  |  |  |
Assets |  |  |  |  |
Cash equivalents |  | 25 |  |  |
Estimate of Fair Value Measurement [Member] | Options Held | Fair Value, Measurements, Recurring |  |  |  |  |
Fuel derivatives: |  |  |  |  |
Derivative Asset, Fair Value, Gross Asset |  | 363 | [4] | 283 | [5]
Fuel derivatives: |  |  |  |  |
Derivative Asset, Fair Value, Gross Liability |  | $ (23) | [4] | $ (35) | [5]
[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] | Cash equivalents are primarily composed of money market investments.
[4] | In the unaudited Condensed Consolidated Balance Sheet amounts are presented as a net asset. See Note 3.
[5] | In the unaudited Condensed Consolidated Balance Sheet amounts are presented as a net asset. See Note 3.

X
- Definition -- None. No documentation exists for this element. -- + References No definition available. + Details
Name: | luv_FuelDerivativeAssetsAbstract
Namespace Prefix: | luv_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition -- None. No documentation exists for this element. -- + References No definition available. + Details
Name: | luv_FuelDerivativeLiabilityAbstract
Namespace Prefix: | luv_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_AssetsAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition This element represents the aggregate of the assets reported on the balance sheet at period end measured at fair value on a recurring basis by the entity. This element is intended to be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. + References No definition available. + Details
Name: | us-gaap_AssetsFairValueDisclosureRecurring
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. + References No definition available. + Details
Name: | us-gaap_CashAndCashEquivalentsFairValueDisclosure
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair value of liability associated with financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 55 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=82849420&loc=SL20226003-175313 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4B -Subparagraph (a),(c) -URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5624163-113959 + Details
Name: | us-gaap_DerivativeAssetFairValueGrossLiability
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Fair value, before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4B -Subparagraph (a),(c) -URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5624163-113959 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 55 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=82849420&loc=SL20226000-175313 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 20 -Section 50 -Paragraph 4D -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=82924980&loc=SL51823488-111719 + Details
Name: | us-gaap_DerivativeFairValueOfDerivativeAsset
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair value, before effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 20 -Section 50 -Paragraph 4D -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=82924980&loc=SL51823488-111719 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4B -Subparagraph (a),(c) -URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5624163-113959 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 55 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=82849420&loc=SL20226000-175313 + Details
Name: | us-gaap_DerivativeFairValueOfDerivativeLiability
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The fair value as of the balance sheet date of firm holdings in debt obligations issued by the US government including short-term Treasury bills, medium-term Treasury notes, and long-term Treasury bonds, as well as debt issued by agencies. Includes both pledged (to counterparties as collateral for financing transactions) and unpledged holdings. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 940 -SubTopic 320 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=35711157&loc=d3e42546-110969 + Details
Name: | us-gaap_FinancialInstrumentsOwnedUSGovernmentAndAgencyObligationsAtFairValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair value as of the balance sheet date of interest rate derivative liabilities, which includes all such derivative instruments in hedging and nonhedging relationships that are recognized as liabilities. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 10 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=77997519&loc=d3e13433-108611 + Details
Name: | us-gaap_InterestRateDerivativeLiabilitiesAtFairValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(12)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(5)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 35 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=82895926&loc=d3e24584-111560 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(6)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(2)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 25 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=75030427&loc=d3e22054-111558 Reference 7: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(1)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 + Details
Name: | us-gaap_InvestmentsFairValueDisclosure
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- References No definition available. + Details
Name: | us-gaap_LiabilitiesAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Fair value of financial and nonfinancial obligations. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258 + Details
Name: | us-gaap_LiabilitiesFairValueDisclosure
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Fair value portion of other assets. + References No definition available. + Details
Name: | us-gaap_OtherAssetsFairValueDisclosure
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_FairValueByMeasurementFrequencyAxis=us-gaap_FairValueMeasurementsRecurringMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel1Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel2Member
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: | luv_FairValueByFairValueAssetDescriptionAxis=us-gaap_CashEquivalentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | luv_FairValueByFairValueAssetDescriptionAxis=us-gaap_CommercialPaperMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | luv_FairValueByFairValueAssetDescriptionAxis=us-gaap_CertificatesOfDepositMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | luv_FairValueByFairValueAssetDescriptionAxis=us-gaap_BankTimeDepositsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

X
- Details
Name: | us-gaap_FairValueByMeasurementBasisAxis=us-gaap_EstimateOfFairValueFairValueDisclosureMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |