SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

Basis of Presentation

Southwest Airlines Co. (the "Company") operates Southwest Airlines, a major domestic airline. The Consolidated Financial Statements include the accounts of the Company and its wholly owned subsidiaries, which include AirTran Holdings, LLC, the successor to AirTran Holdings, Inc. ("AirTran Holdings"), the former parent company of AirTran Airways, Inc. ("AirTran Airways"). The accompanying Consolidated Financial Statements include the results of operations and cash flows for all periods presented and all significant inter-entity balances and transactions have been eliminated. The preparation of financial statements in conformity with generally accepted accounting principles in the United States ("GAAP") requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Actual results could differ from these estimates.

Effective as of January 1, 2018, the Company adopted Accounting Standards Update ("ASU") No. 2014-09, Revenue from Contracts with Customers (the "New Revenue Standard"), ASU No. 2017-07, Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost (the "New Retirement Standard"), and ASU No. 2017-12, Targeted Improvements to Accounting for Hedging Activities (the "New Hedging Standard"). All amounts and disclosures set forth in this Form 10-K reflect the adoption of these ASUs. See Note 2 for further information.

The Company reclassified $198 million and $229 million from Aircraft rentals to Other operating expenses in the Consolidated Statement of Income for the years ended December 31, 2017 and 2016, respectively, to be comparative with the current period's presentation. Aircraft rentals expense included in Other operating expenses for the year ended December 31, 2018, was $161 million. This reclassification had no impact on Operating income, Net income, the Consolidated Balance Sheet, or the Consolidated Statement of Cash Flows.

Cash and Cash Equivalents

Cash in excess of that necessary for operating requirements is invested in short-term, highly liquid, income-producing investments. Investments with original maturities of three months or less when purchased are classified as cash and cash equivalents, which primarily consist of certificates of deposit, money market funds, and investment grade commercial paper issued by major corporations and financial institutions. Cash and cash equivalents are stated at cost, which approximates fair value.

As of December 31, 2018, no cash collateral deposits were provided by or held by the Company from its fuel hedge counterparties, and no cash collateral deposits were held by or provided by the Company to its interest rate hedge counterparties. As of December 31, 2017, $15 million in cash collateral deposits were held by the Company from its fuel hedge counterparties, and no cash collateral deposits were held by or provided by the Company to its interest rate hedge counterparties. Cash collateral amounts provided or held associated with fuel and interest rate derivative instruments are not restricted in any way and earn interest income at an agreed upon rate that approximates the rates earned on short-term securities issued by the U.S. Government. Depending on the fair value of the Company’s fuel and interest rate derivative instruments, the amounts of collateral deposits held or provided at any point in time can fluctuate significantly. See Note 10 for further information on these collateral deposits and fuel derivative instruments.

Short-term and Noncurrent Investments

Short-term investments consist of investments with original maturities of greater than three months but less than twelve months when purchased. These are primarily short-term securities issued by the U.S. Government and certificates of deposit issued by domestic banks. All of these investments are classified as available-for-sale securities and are stated at fair value, which approximates cost. For all short-term investments, at each reset period or upon reinvestment, the Company accounts for the transaction as Proceeds from sales of short-term investments for the security relinquished, and Purchases of short-investments for the security purchased, in the accompanying Consolidated Statement of Cash Flows. Unrealized gains and losses, net of tax, if any, are recognized in Accumulated other comprehensive income (loss) ("AOCI") in the accompanying Consolidated Balance Sheet. Realized net gains and losses on specific investments, if any, are reflected in Interest income in the accompanying Consolidated Statement of Income. Both unrealized and realized gains and/or losses associated with investments were immaterial for all years presented.

Noncurrent investments consist of investments with maturities of greater than twelve months. Noncurrent investments are included as a component of Other assets in the Consolidated Balance Sheet.

Accounts and Other Receivables

Accounts and other receivables are carried at cost. They primarily consist of amounts due from credit card companies associated with sales of tickets for future travel, and amounts due from business partners in the Company’s loyalty program. The allowance for doubtful accounts was immaterial at December 31, 2018 and 2017. In addition, the provision for doubtful accounts and write-offs for 2018, 2017, and 2016 were each immaterial.

Inventories

Inventories primarily consist of aircraft fuel, flight equipment expendable parts, materials, and supplies. All of these items are carried at average cost, less an allowance for obsolescence. These items are generally charged to expense when issued for use. The reserve for obsolescence was $2 million and $45 million at December 31, 2018, and 2017, respectively. In addition, the Company’s provision for obsolescence and write-offs for 2018, 2017, and 2016 were each immaterial.

Property and Equipment

Property and equipment is stated at cost. Capital expenditures include payments made for aircraft, other flight equipment, purchase deposits related to future aircraft deliveries, airport and other facility construction projects, and ground and other property and equipment. Depreciation is provided by the straight-line method to estimated residual values over periods of approximately 25 years for flight equipment, 5 to 30 years for ground property and equipment, and 5 to 30 years, or the expected term of the Company's lease if shorter, for Assets constructed for others, once the asset is placed in service. Residual values estimated for aircraft are approximately 15 percent, for ground property and equipment generally range from 0 to 10 percent, and for Assets constructed for others range from 17 to 75 percent. Property under capital leases and related obligations are initially recorded at an amount equal to the present value of future minimum lease payments computed on the basis of the Company’s incremental borrowing rate or, when known, the interest rate implicit in the lease. Amortization of property under capital leases is on a straight-line basis over the lease term and is included in Depreciation and amortization expense. Leasehold improvements generally are amortized on a straight-line basis over the shorter of the estimated useful life of the improvement or the remaining term of the lease. Assets constructed for others consists of airport improvement projects in which the Company is considered the accounting owner of the facilities. See Note 4 for further information.

During first quarter 2016, the Company made the decision to further simplify its operations and accelerate the retirement of its less-efficient Boeing 737-300 ("Classic") fleet. In September 2017, the Company retired the remaining 61 Classic aircraft as part of this accelerated retirement schedule. This change in retirement dates was considered a change in estimate and was accounted for on a prospective basis as of the dates the decisions were finalized. Therefore, the Company recorded accelerated depreciation expense over the remainder of the useful lives for each Classic aircraft and related parts. See Note 7 for further information regarding the Company's aircraft fleet.

The impacts on expense and earnings from the accelerated depreciation were as follows:



(in millions, except per share amounts)	Year ended December 31, 2017			Year ended December 31, 2016
Depreciation and amortization expense	$	21		$	123
Net income *	$	(19	)	$	(66	)
Net income per basic share	$	(0.03	)	$	(0.11	)
Net income per diluted share	$	(0.03	)	$	(0.10	)

* net of profitsharing benefit and income taxes

The Company evaluates its long-lived assets used in operations for impairment when events and circumstances indicate that the undiscounted cash flows to be generated by that asset are less than the carrying amounts of the asset and may not be recoverable. Factors that would indicate potential impairment include, but are not limited to, significant decreases in the market value of the long-lived asset(s), a significant change in the long-lived asset’s physical condition, and operating or cash flow losses associated with the use of the long-lived asset. If an asset is deemed to be impaired, an impairment loss is recorded for the excess of the asset book value in relation to its estimated fair value.

Aircraft and Engine Maintenance

The cost of scheduled inspections and repairs and routine maintenance costs for all aircraft and engines are charged to Maintenance materials and repairs expense within the accompanying Consolidated Statement of Income as incurred. The Company has maintenance agreements related to certain of its aircraft engines with external service providers, including a "power-by-the-hour" agreement associated with its Boeing 737-700 fleet. Under these agreements, which the Company has determined effectively transfer the risk and create an obligation associated with the maintenance on such engines to the counterparty, expense is recorded commensurate with each hour flown on an engine. In situations where the payments to the counterparty do not sufficiently match the level of services received during the period, expense is recorded on a straight-line basis over the term of the agreement based on the Company's best estimate of expected future aircraft utilization. For its engine maintenance contracts that do not transfer risk to the service provider, the Company records expense on a time and materials basis when an engine repair event takes place. Modifications that significantly enhance the operating performance or extend the useful lives of aircraft or engines are capitalized and amortized over the remaining life of the asset.

Goodwill and Intangible Assets

The Company applies a fair value based impairment test to the carrying value of goodwill and indefinite-lived intangible assets annually on October 1st, or more frequently if certain events or circumstances indicate that an impairment loss may have been incurred. The Company assesses the value of goodwill and indefinite-lived assets under either a qualitative or quantitative approach. Under a qualitative approach, the Company considers various market factors, including applicable key assumptions listed below. These factors are analyzed to determine if events and circumstances could reasonably have affected the fair value of goodwill and indefinite-lived intangible assets. If the Company determines that it is more likely than not that an indefinite-lived intangible asset is impaired, the quantitative approach is used to assess the asset’s implied fair value and the amount of the impairment. Under a quantitative approach, the implied fair value of the Company's identifiable assets and liabilities is calculated based on key assumptions. If the Company assets' carrying value exceeds the fair value calculated using the quantitative approach, an impairment charge is recorded for the difference in fair value and carrying value. During 2016, the Company recorded a $21 million impairment charge associated with leased slots at Newark Liberty International Airport as a result of the FAA announcement, in April 2016, that this airport was being changed to a Level 2 schedule-facilitated airport from its previous designation as Level 3. This impairment loss was reflected in Other operating expenses within the accompanying Consolidated Statement of Income. The Company does not believe this FAA decision is indicative of a similar decision being made at the Company's other slot-controlled airports, Washington Reagan and New York LaGuardia.

The following table is a summary of the Company’s intangible assets, which are included as a component of Other assets in the Company's Consolidated Balance Sheet, as of December 31, 2018 and 2017:



		Year ended December 31, 2018				Year ended December 31, 2017
(in millions)	Weighted-average useful life (in years)	Gross carrying amount		Accumulated amortization		Gross carrying amount		Accumulated Amortization
Customer relationships/marketing agreements	10	$	27	$	25	$	27	$	23
Owned domestic slots (a)	Indefinite	295		n/a		295		n/a
Gate leasehold rights (a)	15	180		78		180		66
Total	14	$	502	$	103	$	502	$	89

(a) Intangible assets primarily consist of acquired leasehold rights to certain airport owned gates, takeoff and landing slots (a "slot" is the right of an air carrier, pursuant to regulations of the FAA, to operate a takeoff or landing at a specific time at certain airports) at certain domestic slot-controlled airports, and certain intangible assets acquired.

The Company's definite lived assets are amortized on a straight-line basis over the useful life of the asset. The aggregate amortization expense for 2018, 2017, and 2016 was $16 million, $13 million, and $17 million, respectively. Estimated aggregate amortization expense for the five succeeding years and thereafter is as follows: 2019 – $13 million, 2020 – $12 million, 2021 – $12 million, 2022 – $12 million, 2023 – $12 million, and thereafter – $45 million.

Revenue Recognition

Tickets sold are initially deferred as Air traffic liability. Passenger revenue is recognized and Air traffic liability is reduced when transportation is provided. Air traffic liability primarily represents tickets sold for future travel dates and funds that are past flight date and remain unused as well as a portion of the Company's liability associated with its loyalty program. The majority of the Company’s tickets sold are nonrefundable. Refundable tickets that are sold but not flown on the travel date can be reused for another flight, up to a year from the date of sale, or refunded, subject to certain conditions. Based on the Company's revenue recognition policy, revenue is recorded at the flight date for a Customer who does not change his/her itinerary and loses his/her funds as the Company has then fulfilled its performance obligation. Amounts collected from passengers for ancillary service fees are also recognized when the service is provided, which is typically the flight date.

Revenue from the estimated spoilage of tickets (including partial tickets) is recorded once the flight date has passed in proportion to the pattern of flights taken by the Customer, which approximates the average period over which the population of Rapid Reward Members redeem their points. Initial spoilage estimates are routinely adjusted and ultimately finalized once the tickets expire, which is typically twelve months after the original purchase date. See Note 5 for further information.

Approximately $566 million, approximately $489 million, and approximately $383 million of the Company's Operating revenues in 2018, 2017, and 2016, respectively, were attributable to foreign operations. The remainder of the Company's Operating revenues, approximately $21.4 billion, approximately $20.7 billion, and approximately $20.0 billion in 2018, 2017, and 2016, respectively, were attributable to domestic operations.

Loyalty Program

The Company records a liability for the relative fair value of providing free travel under its loyalty program for all points earned from flight activity or sold to companies participating in the Company’s Rapid Rewards loyalty program as business partners that are expected to be redeemed for future travel. The loyalty liability represents performance obligations that will be satisfied when a Rapid Rewards loyalty member redeems points for travel or other goods and services, or upon spoilage of the points. Points earned from flight activity are valued at their relative standalone selling price by applying fair value based on historical redemption patterns. Points earned from business partner activity, which primarily consist of points sold, along with related services, to companies participating in the Rapid Rewards loyalty program, are valued using a relative fair value methodology based on the contractual rate which partners pay to Southwest to award Rapid Rewards points to the business partner’s customers. For points that are expected to expire unused, the Company recognizes spoilage in proportion to the pattern of points used by the Customer, which approximates the average period over which the population of Rapid Reward Members redeem their points. The Company records passenger revenue related to air transportation when the transportation is delivered. The marketing elements are recognized as Other - net revenue when earned. See Note 5 for further information.

Advertising

Advertising costs are charged to expense as incurred. Advertising and promotions expense for the years ended December 31, 2018, 2017, and 2016 was $215 million, $224 million, and $232 million, respectively, and is included as a component of Other operating expense in the accompanying Consolidated Statement of Income.

Share-based Employee Compensation

The Company has share-based compensation plans covering certain Employees, including a plan that also covers the Company’s Board of Directors. The Company accounts for share-based compensation based on its grant date fair value. See Note 9 for further information.

Financial Derivative Instruments

The Company accounts for financial derivative instruments at fair value and applies hedge accounting rules where appropriate. The Company utilizes various derivative instruments, including jet fuel, crude oil, unleaded gasoline, and heating oil-based derivatives, to attempt to reduce the risk of its exposure to jet fuel price increases. These instruments are accounted for as cash flow hedges upon proper qualification. The Company also has interest rate swap agreements to convert a portion of its fixed-rate debt to floating rates and has swap agreements that convert certain floating-rate debt to a fixed-rate. The majority of these interest rate hedges are appropriately designated as either fair value hedges or as cash flow hedges.

Since the majority of the Company’s financial derivative instruments are not traded on a market exchange, the Company estimates their fair values. Depending on the type of instrument, the values are determined by the use of present value methods or option value models with assumptions about commodity prices based on those observed in underlying markets.

The Company adopted the New Hedging Standard as of January 1, 2018. See Note 2 for further information on this adoption.

All cash flows associated with purchasing and selling derivatives are classified as operating cash flows in the Consolidated Statement of Cash Flows, within Changes in certain assets and liabilities. The Company classifies its cash collateral provided to or held from counterparties in a "net" presentation on the Consolidated Balance Sheet against the fair value of the derivative positions with those counterparties. See Note 10 for further information.

Software Capitalization

The Company capitalizes certain internal and external costs related to the acquisition and development of internal use software during the application development stages of projects. The Company amortizes these costs using the straight-line method over the estimated useful life of the software, which is typically five to fifteen years. Costs incurred during the preliminary project or the post-implementation/operation stages of the project are expensed as incurred. Capitalized computer software, included as a component of Ground property and equipment in the accompanying Consolidated Balance Sheet, net of accumulated depreciation, was $674 million and $654 million at December 31, 2018, and 2017, respectively. Computer software depreciation expense was $155 million, $168 million, and $111 million for the years ended December 31, 2018, 2017, and 2016, respectively, and is included as a component of Depreciation and amortization expense in the accompanying Consolidated Statement of Income. The Company evaluates internal use software for impairment on a quarterly basis; if it is determined the value of an asset was not recoverable or it qualifies for impairment, a charge will be recorded to write down the software to the lower of its carrying value or fair value. The Company had no significant impairments during 2018, 2017, or 2016.

Income Taxes

The Company accounts for deferred income taxes utilizing an asset and liability method, whereby deferred tax assets and liabilities are recognized based on the tax effect of temporary differences between the financial statements and the tax basis of assets and liabilities, as measured by current enacted tax rates. The Company also evaluates the need for a valuation allowance to reduce deferred tax assets to estimated recoverable amounts.

The Company’s policy for recording interest and penalties associated with uncertain tax positions is to record such items as a component of income before income taxes. Penalties are recorded in Other (gains) losses, net, and interest paid or received is recorded in Interest expense or Interest income, respectively, in the accompanying Consolidated Statement of Income. There were no material amounts recorded for penalties and interest related to uncertain tax positions for all years presented. See Note 14 for further information.

Concentration Risk

Approximately 83 percent of the Company’s full-time equivalent Employees are unionized and are covered by collective-bargaining agreements. A percentage of the Company's unionized Employees, including its Flight Attendants, Customer Service Agents, Mechanics, Flight Simulator Technicians, and Material Specialists, are in discussions on labor agreements. Those unionized Employee groups in discussions represent approximately 43 percent of the Company’s full-time equivalent Employees as of December 31, 2018.

The Company attempts to minimize its concentration risk with regards to its cash, cash equivalents, and its investment portfolio. This is accomplished by diversifying and limiting amounts among different counterparties, the type of investment, and the amount invested in any individual security or money market fund.

To manage risk associated with financial derivative instruments held, the Company selects and will periodically review counterparties based on credit ratings, limits its exposure to a single counterparty, and monitors the market position of the program and its relative market position with each counterparty. The Company also has agreements with counterparties containing early termination rights and/or bilateral collateral provisions whereby security is required if market risk exposure exceeds a specified threshold amount or credit ratings fall below certain levels. Collateral deposits provided to or held from counterparties serve to decrease, but not totally eliminate, the credit risk associated with the Company’s hedging program. See Note 10 for further information.

As of December 31, 2018, the Company operated an all-Boeing fleet, all of which are variations of the Boeing 737. If the Company were unable to acquire additional aircraft or associated aircraft parts from Boeing, or Boeing were unable or unwilling to make timely deliveries of aircraft or associated parts, or to provide adequate support for its products, the Company’s operations would be materially adversely impacted. In addition, the Company would be materially adversely impacted in the event of a mechanical or regulatory issue associated with the Boeing 737 aircraft type, whether as a result of downtime for part or all of the Company’s fleet, increased maintenance costs, or because of a negative perception by the flying public. The Company is also dependent on sole or limited suppliers for aircraft engines and certain other aircraft parts and services and would, therefore, also be materially adversely impacted in the event of the unavailability of, inadequate support for, or a mechanical or regulatory issue associated with, engines and other parts.

The Company has historically entered into agreements with some of its co-brand, payment, and loyalty partners that contain exclusivity aspects which place certain confidential restrictions on the Company from entering into certain arrangements with other payment and loyalty partners. These arrangements generally extend for the terms of the agreements, which typically are for five to seven years, but none of which are more than 10 years in length. Some of these agreements automatically renew on an annual basis, unless either party objects to such extension. The Company believes the financial benefits generated by the exclusivity aspects of these arrangements outweigh the risks involved with such agreements.