Commitments and Contingencies - Capital Commitments (Details) $ in Billions	3 Months Ended	6 Months Ended
Jun. 30, 2025 USD ($) aircraft	Jun. 30, 2025 USD ($) aircraft
-8 Firm Orders
Unrecorded Unconditional Purchase Obligation [Line Items]
Number of aircraft deliveries \| aircraft	17	28
Aircraft
Unrecorded Unconditional Purchase Obligation [Line Items]
2025	$ 2.9	$ 2.9
2026	2.4	2.4
2027	2.5	2.5
2028	2.8	2.8
2029	2.5	2.5
2030 and thereafter	2.8	2.8
Total	15.9	15.9
Aircraft \| Year 2025 \| MAX
Unrecorded Unconditional Purchase Obligation [Line Items]
2025	1.6	$ 1.6
Number of aircraft deliveries \| aircraft		73
Aircraft \| Year 2024 \| MAX
Unrecorded Unconditional Purchase Obligation [Line Items]
2026	$ 1.3	$ 1.3
Number of aircraft deliveries \| aircraft		63
Aircraft \| Year 2024 \| -7 Firm Orders
Unrecorded Unconditional Purchase Obligation [Line Items]
Number of aircraft deliveries \| aircraft		27
Aircraft \| Year 2024 \| -8 Firm Orders
Unrecorded Unconditional Purchase Obligation [Line Items]
Number of aircraft deliveries \| aircraft		36

Long-Term Purchase Commitment, Aircraft Deliveries

No definition available.

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

- Definition

Unrecorded Unconditional Purchase Obligation, to be Paid, after Year Four

+ References

No definition available.

+ Details

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

- Definition

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). Includes, but is not limited to, lease not yet commenced.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 440
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482648/440-10-50-4

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478964/842-20-50-3

+ Details

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

- Definition

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). Includes, but is not limited to, lease not yet commenced.

+ References

+ Details

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

- Definition

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). Includes, but is not limited to, lease not yet commenced.

+ References

+ Details

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

- Definition

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). Includes, but is not limited to, lease not yet commenced.

+ References

+ Details

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

- Definition

Amount of unrecorded obligation to transfer funds in future for fixed or minimum amount or quantity of product and service at fixed or minimum price. Includes, but is not limited to, lease not yet commenced and take-or-pay and throughput contracts.

+ References

+ Details

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

- Definition

Amount of fixed and determinable portion of unrecorded unconditional purchase obligation to be paid in remainder of current fiscal year.

+ References

No definition available.

+ Details

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

- 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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 440
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482648/440-10-50-4

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 440
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482648/440-10-50-4

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 440
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482648/440-10-50-4

+ Details

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

- Details

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

- Details

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

- Details

Name:	luv_DeliveryAxis=luv_Year2025Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	luv_DeliveryAxis=luv_Year2024Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_AircraftTypeAxis=luv_B7377MaxMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: