XML 63 R51.htm IDEA: XBRL DOCUMENT
v3.21.2

Fair Value Measurements - Narrative (Details) | 3 Months Ended | 9 Months Ended |  |
--- | --- | --- | --- | ---
Sep. 30, 2021 USD ($) $ / shares | Sep. 30, 2020 USD ($) | Sep. 30, 2021 USD ($) $ / shares | Sep. 30, 2020 USD ($) | Dec. 31, 2020 USD ($) | May 01, 2020 USD ($) $ / shares
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |  |
Initial conversion price (in USD per share) | $ / shares | $ 38.48 |  | $ 38.48 |  |  |
Other (gains) losses, net | $ (29,000,000) | $ (35,000,000) | $ 32,000,000 | $ (95,000,000) |  |
Capital in excess of par value | 4,251,000,000 |  | 4,251,000,000 |  | $ 4,191,000,000 |
Loss on repurchase of debt instrument | (12,000,000) | $ 0 | $ (12,000,000) | $ 0 |  |
Equity feature of partial extinguishment of convertible notes | $ (42,000,000) |  |  |  |  |
Amortization period (in years) | 5 years |  |  |  |  |
1.250 Convertible Senior Notes due 2025 | Convertible Debt |  |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |  |
Principal amount |  |  |  |  |  | $ 2,300,000,000
Stated interest rate | 1.25% |  | 1.25% |  |  | 1.25%
Initial conversion ratio | 0.0259909 |  |  |  |  |
Initial conversion price (in USD per share) | $ / shares |  |  |  |  |  | $ 38.48
Effective interest rate | 5.20% |  | 5.20% |  |  |
Interest expense | $ 40,000,000 |  | $ 96,000,000 |  |  |
Unamortized debt discount | (289,000,000) |  | (289,000,000) |  | $ (355,000,000) |
If-converted value in excess of principal amount | 748,000,000 |  |  |  |  |
1.250 Convertible Senior Notes due 2025 | Convertible Debt | September 2021 |  |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |  |
Principal amount of debt repurchased | 80,000,000 |  | 80,000,000 |  |  |
Cash paid for repurchased debt | 121,000,000 |  | 121,000,000 |  |  |
Loss on repurchase of debt instrument | 12,000,000 |  |  |  |  |
Unamortized debt discount | (12,000,000) |  | (12,000,000) |  |  |
Equity feature of partial extinguishment of convertible notes |  |  | 42,000,000 |  |  |
1.250 Convertible Senior Notes due 2025 | Convertible Debt | Non-Cash Amortization of Debt Discount |  |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |  |
Interest expense | 29,000,000 |  | 66,000,000 |  |  |
1.250 Convertible Senior Notes due 2025 | Convertible Debt | Non-Cash Amortization of Debt Issuance Costs |  |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |  |
Interest expense | 4,000,000 |  | 8,000,000 |  |  |
1.250 Convertible Senior Notes due 2025 | Convertible Debt | Contractual Coupon Interest Expense |  |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |  |
Interest expense | $ 7,000,000 |  | $ 22,000,000 |  |  |

X
- Definition Value received from shareholders in common stock-related transactions that are in excess of par value or stated value and amounts received from other stock-related transactions. Includes only common stock transactions (excludes preferred stock transactions). May be called contributed capital, capital in excess of par, capital surplus, or paid-in capital. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(30)(a)(1)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_AdditionalPaidInCapitalCommonStock
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The amount of subsequent adjustments to additional paid in capital for convertible financial instruments where a component of equity and a component of debt are recognized. + References No definition available. + Details
Name: | us-gaap_AdjustmentsToAdditionalPaidInCapitalEquityComponentOfConvertibleDebtSubsequentAdjustments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The price per share of the conversion feature embedded in the debt instrument. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 50 -Paragraph 5 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=123466204&loc=SL6031898-161870 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 50 -Paragraph 1B -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611 + Details
Name: | us-gaap_DebtInstrumentConvertibleConversionPrice1
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:perShareItemType
Balance Type: | na
Period Type: | instant

X
- Definition Ratio applied to the conversion of debt instrument into equity with equity shares divided by debt principal amount. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 50 -Paragraph 1B -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=123467817&loc=d3e21521-112644 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 6 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=123467817&loc=d3e21506-112644 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(5)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=123467817&loc=d3e21475-112644 + Details
Name: | us-gaap_DebtInstrumentConvertibleConversionRatio1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:pureItemType
Balance Type: | na
Period Type: | duration

X
- Definition The amount by which the convertible debt's if-converted value exceeds its principle amount at the balance sheet date, regardless of whether the instrument is currently convertible. This element applies to public companies only. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 50 -Paragraph 5 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=123466204&loc=SL6031898-161870 + Details
Name: | us-gaap_DebtInstrumentConvertibleIfConvertedValueInExcessOfPrincipal
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Remaining amortization period for discount on the liability component of convertible debt which may be settled in cash upon conversion, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 50 -Paragraph 5 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=123466204&loc=SL6031898-161870 + Details
Name: | us-gaap_DebtInstrumentConvertibleRemainingDiscountAmortizationPeriod1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Face (par) amount of debt instrument at time of issuance. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 50 -Paragraph 1B -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=124435984&loc=d3e28551-108399 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 55 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=124429444&loc=SL124452920-239629 Reference 5: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 55 -Paragraph 69C -URI http://asc.fasb.org/extlink&oid=123466577&loc=SL123495737-112612 Reference 6: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 55 -Paragraph 69B -URI http://asc.fasb.org/extlink&oid=123466577&loc=SL123495735-112612 + Details
Name: | us-gaap_DebtInstrumentFaceAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 50 -Paragraph 6 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=123466204&loc=SL6036836-161870 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=124435984&loc=d3e28551-108399 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=124429444&loc=SL124452920-239629 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(1)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_DebtInstrumentInterestRateEffectivePercentage
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Contractual interest rate for funds borrowed, under the debt agreement. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 50 -Paragraph 1B -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(1)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Fair value amount of debt instrument that was repurchased. + References No definition available. + Details
Name: | us-gaap_DebtInstrumentRepurchaseAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Face (par) amount of the original debt instrument that was repurchased. + References No definition available. + Details
Name: | us-gaap_DebtInstrumentRepurchasedFaceAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of unamortized debt discount (premium) and debt issuance costs. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 55 -Paragraph 69C -URI http://asc.fasb.org/extlink&oid=123466577&loc=SL123495737-112612 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (b)(2) -URI http://asc.fasb.org/extlink&oid=123466204&loc=SL6031897-161870 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 50 -Paragraph 1D -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495340-112611 Reference 4: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 55 -Paragraph 69B -URI http://asc.fasb.org/extlink&oid=123466577&loc=SL123495735-112612 Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=124435984&loc=d3e28555-108399 + Details
Name: | us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
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_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of gain (loss) from the difference between the repurchase price of a debt instrument initially issued by the entity and the net carrying amount of the debt at the time of its repurchase. + References No definition available. + Details
Name: | us-gaap_GainLossOnRepurchaseOfDebtInstrument
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of the cost of borrowed funds accounted for as interest expense for debt. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 50 -Paragraph 6 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=123466204&loc=SL6036836-161870 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.8) -URI http://asc.fasb.org/extlink&oid=123367319&loc=SL114868664-224227 Reference 3: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 55 -Paragraph 69F -URI http://asc.fasb.org/extlink&oid=123466577&loc=SL123495745-112612 Reference 4: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 55 -Paragraph 69E -URI http://asc.fasb.org/extlink&oid=123466577&loc=SL123495743-112612 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 50 -Paragraph 1F -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495355-112611 + Details
Name: | us-gaap_InterestExpenseDebt
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of income (expense) related to nonoperating activities, classified as other. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.9) -URI http://asc.fasb.org/extlink&oid=123367319&loc=SL114868664-224227 + Details
Name: | us-gaap_OtherNonoperatingIncomeExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | us-gaap_DebtInstrumentAxis=luv_A1250ConvertibleSeniorNotesDue2025Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=us-gaap_ConvertibleDebtMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentRedemptionPeriodAxis=us-gaap_DebtInstrumentRedemptionPeriodOneMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | luv_NatureOfInterestExpenseAxis=luv_NonCashAmortizationOfDebtDiscountMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | luv_NatureOfInterestExpenseAxis=luv_NonCashAmortizationOfDebtIssuanceCostsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | luv_NatureOfInterestExpenseAxis=luv_ContractualCouponInterestExpenseMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |