Basis of Presentation (Policies)	9 Months Ended
Basis of Presentation (Policies)	Sep. 30, 2015
Accounting Policies [Abstract]
Basis of Presentation	The unaudited Condensed Consolidated Financial Statements for the interim periods ended September 30, 2015 and 2014 include all adjustments which are, in the opinion of management, necessary for a fair presentation of the results for the interim periods. This includes all normal and recurring adjustments and elimination of significant intercompany transactions. Financial results for the Company and airlines in general can be seasonal in nature. In many years, the Company's revenues, as well as its operating income and net income, have been better in its second and third fiscal quarters than in its first and fourth fiscal quarters. Air travel is also significantly impacted by general economic conditions, the amount of disposable income available to consumers, unemployment levels, corporate travel budgets, and other factors beyond the Company's control. These and other factors, such as the price of jet fuel in some periods, the nature of the Company's fuel hedging program, the periodic volatility of commodities used by the Company for hedging jet fuel, and the requirements related to hedge accounting, have created, and may continue to create, significant volatility in the Company's financial results. See Note 3 for further information on fuel and the Company's hedging program. Operating results for the three and nine months ended September 30, 2015, are not necessarily indicative of the results that may be expected for future quarters or for the year ended December 31, 2015. For further information, refer to the Consolidated Financial Statements and footnotes thereto included in the Southwest Airlines Co. Annual Report on Form 10-K for the year ended December 31, 2014.
Derivatives	The Company is party to certain interest rate swap agreements that are accounted for as either fair value hedges or cash flow hedges, as defined in the applicable accounting guidance for derivative instruments and hedging. Two of the Company's interest rate swap agreements qualify for the “shortcut” method of accounting for hedges, which dictates that the hedges are assumed to be perfectly effective, and, thus, there is no ineffectiveness to be recorded in earnings. For the Company’s interest rate swap agreements that do not qualify for the "shortcut" method of accounting, ineffectiveness is required to be measured at each reporting period. Upon proper qualification, the Company accounts for its fuel derivative instruments as cash flow hedges. Generally, utilizing hedge accounting, all periodic changes in fair value of the derivatives designated as hedges that are considered to be effective are recorded in Accumulated other comprehensive income (loss) ("AOCI") until the underlying jet fuel is consumed. See Note 4. The Company’s results are subject to the possibility that periodic changes will not be effective, as defined, or that the derivatives will no longer qualify for hedge accounting. Ineffectiveness results when the change in the fair value of the derivative instrument exceeds the change in the value of the Company’s expected future cash outlay to purchase and consume jet fuel. To the extent that the periodic changes in the fair value of the derivatives are ineffective, the ineffective portion is recorded to Other (gains) losses, net, in the unaudited Condensed Consolidated Statement of Comprehensive Income. Likewise, if a hedge ceases to qualify for hedge accounting, any change in the fair value of derivative instruments since the last reporting period is recorded to Other (gains) losses, net, in the unaudited Condensed Consolidated Statement of Comprehensive Income in the period of the change; however, any amounts previously recorded to AOCI would remain there until such time as the original forecasted transaction occurs, at which time these amounts would be reclassified to Fuel and oil expense. When the Company has sold derivative positions in order to effectively “close” or offset a derivative already held as part of its fuel derivative instrument portfolio, any subsequent changes in fair value of those positions are marked to market through earnings. Likewise, any changes in fair value of those positions that were offset by entering into the sold positions and were de-designated as hedges are concurrently marked to market through earnings. However, any changes in value related to hedges that were deferred as part of AOCI while designated as a hedge would remain until the originally forecasted transaction occurs. In a situation where it becomes probable that a fuel hedged forecasted transaction will not occur, any gains and/or losses that have been recorded to AOCI would be required to be immediately reclassified into earnings. The Company did not have any such situations occur during 2014, or during the nine months ended September 30, 2015. In some situations, an entire commodity type used in hedging may cease to qualify for special hedge accounting treatment.
Fair Value of Financial Instruments	Accounting standards pertaining to fair value measurements establish a three-tier fair value hierarchy, which prioritizes the inputs used in measuring fair value. These tiers include: Level 1, defined as observable inputs such as quoted prices in active markets; Level 2, defined as inputs other than quoted prices in active markets that are either directly or indirectly observable; and Level 3, defined as unobservable inputs in which little or no market data exists, therefore requiring an entity to develop its own assumptions. As of September 30, 2015, the Company held certain items that are required to be measured at fair value on a recurring basis. These included cash equivalents, short-term investments (primarily treasury bills and certificates of deposit), certain noncurrent investments, interest rate derivative contracts, fuel derivative contracts, and available-for-sale securities. The majority of the Company’s short-term investments consist of instruments classified as Level 1. However, the Company has certificates of deposit, commercial paper, and Eurodollar time deposits that are classified as Level 2, due to the fact that the fair value for these instruments is determined utilizing observable inputs in non-active markets. Noncurrent investments consist of certain auction rate securities, primarily those collateralized by student loan portfolios, which are guaranteed by the U.S. Government. Other available-for-sale securities primarily consist of investments associated with the Company’s excess benefit plan. The Company’s fuel and interest rate derivative instruments consist of over-the-counter contracts, which are not traded on a public exchange. Fuel derivative instruments include swaps, as well as different types of option contracts, whereas interest rate derivatives consist solely of swap agreements. See Note 3 for further information on the Company’s derivative instruments and hedging activities. The fair values of swap contracts are determined based on inputs that are readily available in public markets or can be derived from information available in publicly quoted markets. Therefore, the Company has categorized these swap contracts as Level 2. The Company’s Treasury Department, which reports to the Chief Financial Officer, determines the value of option contracts utilizing an option pricing model based on inputs that are either readily available in public markets, can be derived from information available in publicly quoted markets, or are provided by financial institutions that trade these contracts. The option pricing model used by the Company is an industry standard model for valuing options and is the same model used by the broker/dealer community (i.e., the Company’s counterparties). The inputs to this option pricing model are the option strike price, underlying price, risk free rate of interest, time to expiration, and volatility. Because certain inputs used to determine the fair value of option contracts are unobservable (principally implied volatility), the Company has categorized these option contracts as Level 3. Volatility information is obtained from external sources, but is analyzed by the Company for reasonableness and compared to similar information received from other external sources. The fair value of option contracts considers both the intrinsic value and any remaining time value associated with those derivatives that have not yet settled. The Company also considers counterparty credit risk and its own credit risk in its determination of all estimated fair values. To validate the reasonableness of the Company’s option pricing model, on a monthly basis, the Company compares its option valuations to third party valuations. If any significant differences were to be noted, they would be researched in order to determine the reason. However, historically, no significant differences have been noted. The Company has consistently applied these valuation techniques in all periods presented and believes it has obtained the most accurate information available for the types of derivative contracts it holds.
Revenue Recognition, Multiple-deliverable Arrangements, Description	During July 2015, the Company executed an amended co-branded credit card agreement (“Agreement”) with Chase Bank USA, N.A. (“Chase”), through which the Company sells loyalty points and other items to Chase. The Company's Rapid Rewards program members ("Members") are able to accrue loyalty points based on purchases using the Chase co-branded Southwest Visa credit card. The Agreement materially modifies the previously existing agreement between Chase and the Company. Consideration received as part of this Agreement is subject to ASU 2009-13, "Multiple-Deliverable Revenue Arrangements - a consensus of the FASB Emerging Issues Task Force".

Disclosure of accounting policy for revenue recognition for multiple-deliverable arrangements including, at a minimum (as applicable): (1) the nature of such arrangements, (2) the significant deliverables within the arrangements, (3) the general timing of delivery or performance of service for the deliverables within the arrangements, (4) performance-, cancellation-, termination- or refund-type provisions, (5) a discussion of the significant factors, inputs, assumptions, and methods used to determine selling price (whether vendor-specific objective evidence, third-party evidence, or estimated selling price) for the significant deliverables, (6) whether the significant deliverables in the arrangements qualify as separate units of accounting and the reasons that they do not qualify as separate units of accounting, if applicable, and (7) the general timing of revenue recognition for significant units of accounting. This element is applicable to all multiple-deliverable arrangements, including software arrangements (for example, software products, upgrades or enhancements, postcontract customer support, or services).