Name:	luv_CapitalCommitmentsFrom2019ShiftingIntoFuturePeriodsAssociatedWithContractualObligationsThatDidNotTakePlaceIn2019Or2020
Namespace Prefix:	luv_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Capital Commitments from 2020 Shifting into Future Periods, Associated with Contractual Obligations that Did Not Take Place in 2019 or 2020

No definition available.

Name:	luv_CapitalCommitmentsFrom2020ShiftingIntoFuturePeriodsAssociatedWithContractualObligationsThatDidNotTakePlaceIn2019Or2020
Namespace Prefix:	luv_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

The amount the company has an option to purchase within the contractual purchase commitment.

No definition available.

Name:	luv_LongTermPurchaseCommitmentsOptions737Mx
Namespace Prefix:	luv_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

Number of Aircraft Grounded Under Emergency Order on March 13, 2019

No definition available.

Name:	luv_NumberOfAircraftGroundedUnderEmergencyOrderOnMarch132019
Namespace Prefix:	luv_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

Property, Plant and Equipment, Maximum Number of Purchased Aircraft Expected to be Delivered through December 31, 2021, based on the Memorandum of Understanding Reached in December 2020

No definition available.

Name:	luv_PropertyPlantAndEquipmentMaximumNumberOfPurchasedAircraftExpectedToBeDeliveredThroughDecember312021BasedOnTheMemorandumOfUnderstandingReachedInDecember2020
Namespace Prefix:	luv_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

Property, Plant and Equipment, Number of Aircraft Expected to be Leased in 2021

No definition available.

Name:	luv_PropertyPlantAndEquipmentNumberOfAircraftExpectedToBeLeasedIn2021
Namespace Prefix:	luv_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Property, Plant and Equipment, Number of Aircraft Leased

No definition available.

Name:	luv_PropertyPlantAndEquipmentNumberOfAircraftLeased
Namespace Prefix:	luv_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Property, Plant and Equipment, Total Number of Aircraft Expected to be Delivered in 4Q20 and 2021

No definition available.

Name:	luv_PropertyPlantAndEquipmentTotalNumberOfAircraftExpectedToBeDeliveredIn2020And2021
Namespace Prefix:	luv_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Property, Plant and Equipment, Total Number of Aircraft Expected to be Leased in 4Q20 and 2021

No definition available.

Name:	luv_PropertyPlantAndEquipmentTotalNumberOfAircraftExpectedToBeLeasedIn4Q20And2021
Namespace Prefix:	luv_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

Total Capital Commitments Shifting Into Future Periods, Associated with Contractual Obligations that Did Not Take Place in 2019 or 2020

No definition available.

Name:	luv_TotalCapitalCommitmentsShiftingIntoFuturePeriodsAssociatedWithContractualObligationsThatDidNotTakePlaceIn2019Or2020
Namespace Prefix:	luv_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

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.

No definition available.

Name:	us-gaap_LongTermPurchaseCommitmentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Number of units of goods that must be purchased within the specified time period of the agreement to avoid penalties or unfavorable effects on pricing, among other adverse consequences.

No definition available.

Name:	us-gaap_LongTermPurchaseCommitmentMinimumQuantityRequired
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Amount of fixed and determinable portion of unrecorded unconditional purchase obligation to be paid in fifth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 440
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121559207&loc=d3e25336-109308

Name:	us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFifthAnniversary
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Amount of fixed and determinable portion of unrecorded unconditional purchase obligation to be paid in next fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

Name:	us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFirstAnniversary
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Amount of fixed and determinable portion of unrecorded unconditional purchase obligation to be paid in fourth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

Name:	us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFourthAnniversary
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Amount of fixed and determinable portion of unrecorded unconditional purchase obligation to be paid in second fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

Name:	us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnSecondAnniversary
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Amount of fixed and determinable portion of unrecorded unconditional purchase obligation to be paid in third fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

Name:	us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnThirdAnniversary
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Name:	us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis=luv_AircraftMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	srt_AircraftTypeAxis=srt_B737MaxMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	srt_AircraftTypeAxis=luv_B7378MaxDomain
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	srt_AircraftTypeAxis=luv_B7377MaxDomain
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	srt_AircraftTypeAxis=luv_B7378MAXMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: