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Summary of Significant Accounting Policies (Policies) | 12 Months Ended
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Dec. 31, 2014
Accounting Policies [Abstract] |
Basis of Presentation | 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. On May 2, 2011 (the “acquisition date”), the Company acquired all of the outstanding equity of AirTran Holdings, Inc. (“AirTran Holdings”), the former parent company of AirTran Airways, Inc. (“AirTran Airways”). Throughout these Notes, the Company makes reference to AirTran, which is meant to be inclusive of the following: (i) for periods prior to the acquisition date, AirTran Holdings and its subsidiaries, including, among others, AirTran Airways; and (ii) for periods on and after the acquisition date, AirTran Holdings, LLC, the successor to AirTran Holdings, and its subsidiaries, including among others, 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. Certain prior period amounts have been reclassified to conform to the current presentation. In the Consolidated Statement of Cash Flows for the year ended December 31, 2013, the Company has reclassified $14 million from Capital expenditures to Assets constructed for others. See Note 4 for further information.
Cash and cash equivalents | 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, 2014, $266 million in cash collateral deposits were provided by the Company to 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, 2013, the Company had no cash collateral deposits held by or provided by the Company to its fuel hedge counterparties and the Company had provided cash collateral deposits totaling $32 million 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 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. At December 31, 2014, these primarily consisted of the Company’s auction rate security instruments that it expects will not be redeemed during 2015. See Note 11 for further information. Noncurrent investments are included as a component of Other assets in the Consolidated Balance Sheet.
Accounts and other receivables | 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, amounts due from business partners in the Company’s frequent flyer program, and amounts due from counterparties associated with fuel derivative instruments that have settled. The allowance for doubtful accounts was immaterial at December 31, 2014 and 2013. In addition, the provision for doubtful accounts and write-offs for 2014 and 2013 were each immaterial.
Inventories | Inventories Inventories consist primarily 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 $46 million and $36 million at December 31, 2014, and 2013, respectively. In addition, the Company’s provision for obsolescence and write-offs for 2014, 2013, and 2012 were each immaterial.
Property and equipment | Property and equipment Property and equipment is stated at cost. Capital expenditures includes payments made for aircraft, other flight equipment, purchase deposits related to future aircraft deliveries, and ground and other property and equipment. Depreciation is provided by the straight-line method to estimated residual values over periods generally ranging from 23 to 25 years for flight equipment and 5 to 30 years for ground property and equipment once the asset is placed in service. Residual values estimated for aircraft generally range from 2 to 20 percent and for ground property and equipment generally range from 0 to 10 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 primarily consists of airport improvement projects, once placed into service, in which the Company is considered the accounting owner of the facilities, and such assets are amortized to estimated residual value over the term of the Company's lease or the expected life of the asset. See Note 4 for further information. 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. During first quarter 2012 the Company changed the estimated retirement dates of several 737-300 and 737-500 aircraft based on revisions in the Company’s fleet plan. This change, which was accounted for on a prospective basis, resulted in an acceleration of depreciation expense, since the majority of these aircraft had previously been expected to retire in periods beyond 2012, but were subsequently expected to be retired during 2012. The impact of this change on the year ended December 31, 2012 was an increase to Depreciation expense of $12 million. Excluding the impact of Profitsharing and income taxes, the change resulted a $6 million decrease to Net income and a $0.01 decrease to Basic and Diluted Net income per share for the year ended December 31, 2012. During third quarter 2012 the Company changed the estimated residual values of its entire fleet of owned 737-300 and 737-500 aircraft. This change was based on an agreement entered into during July 2012, pursuant to which the Company will lease or sublease certain aircraft to Delta Air Lines, Inc., and the resulting impact this transaction will have on how the Company manages the ultimate retirement of its owned 737-300 and 737-500 aircraft. See Note 7 for further information on the lease/sublease transaction. Based on the expected retirement dates and then current and expected future market conditions related to its owned 737-300 and 737-500 aircraft, the Company reduced the residual values of these aircraft from approximately ten percent of original cost to approximately two percent of original cost. As this reduction in residual value was considered a change in estimate, it was accounted for on a prospective basis, and thus the Company will record additional depreciation expense over the remainder of the useful lives for each aircraft. The impact of this change on the year ended December 31, 2012 was an increase to Depreciation expense of $34 million. Excluding the impact of Profitsharing and income taxes, the change resulted an $18 million decrease to Net income and a $0.02 decrease to Basic and Diluted Net income per share for the year ended December 31, 2012.
Aircraft and engine maintenance | 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 as incurred. The Company also has “power-by-the-hour” agreements related to certain of its aircraft engines with external service providers. Under these agreements, which the Company has determined effectively transfers the risk and creates 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 our 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 | Goodwill and intangible assets The Company applies a fair value based impairment test to the carrying value of goodwill and indefinite-lived intangible assets on an annual basis (as of October 1), or more frequently if certain events or circumstances indicate that an impairment loss may have been incurred. The FASB standard “Testing Indefinite-Lived Intangible Assets for Impairment” gives companies the option to perform a qualitative assessment to determine whether it is more likely than not that an indefinite-lived intangible asset is impaired rather than calculating the fair value of the indefinite-lived intangible asset. The Company adopted this standard and has applied the provisions to its annual indefinite-lived intangible asset impairment test for 2014. The Company first utilizes a qualitative approach and analyzes various factors to determine if events and circumstances have affected the fair value of the goodwill and indefinite-lived intangible assets. If the Company determines it is more likely than not that the asset value may be impaired, the Company then uses the quantitative approach to assess the asset’s fair value and amount of impairment. As a result of the Company’s qualitative analyses performed during 2014 the Company concluded it was more likely than not that the fair values of its Goodwill and Indefinite-lived intangible assets was greater than the carrying value and; therefore, a quantitative assessment was not necessary. Intangible assets primarily consist of acquired leasehold rights to certain airport owned gates at Chicago’s Midway International Airport, take-off and landing slots at certain domestic slot-controlled airports, and certain intangible assets recognized from the AirTran acquisition. 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, 2014 and 2013:
|  |  | Year ended December 31, 2014 |  | Year ended December 31, 2013
(in millions) | Weighted-average useful life (in years) |  | Gross carrying amount |  | Accumulated amortization |  | Gross carrying amount |  | Accumulated Amortization
Customer relationships/marketing agreements | 9 |  | $ | 38 |  |  | $ | 26 |  |  | $ | 39 |  |  | $ | 23 |
Trademarks/trade names | 6 |  | 36 |  |  | 30 |  |  | 36 |  |  | 25 |
Owned domestic slots | Indefinite |  | 303 |  |  | n/a |  |  | 93 |  |  | n/a |
Leased domestic slots (a) | 39 |  | 19 |  |  | 5 |  |  | 19 |  |  | 4 |
Non-compete agreements | 2 |  | 5 |  |  | 5 |  |  | 5 |  |  | 5 |
Gate leasehold rights | 19 |  | 60 |  |  | 32 |  |  | 60 |  |  | 29 |
Total | 15 |  | $ | 461 |  |  | $ | 98 |  |  | $ | 252 |  |  | $ | 86 |
(a) Useful life of leased slots is based on the stated lease term. During fourth quarter 2013, following the Company’s acquisition of additional slots at New York’s LaGuardia Airport, the Company made the determination that all of its owned domestic slots should be assigned an indefinite life and would thus not be subject to further amortization, including those that are owned but leased to other carriers. In addition, during first quarter 2014, the Company acquired additional slots at Washington’s Ronald Reagan National Airport which were also assigned an indefinite life. Among other factors, the determination that all of the Company's owned domestic slots should be assigned an indefinite life was due to the Company’s reassessment of the current size and importance of its operations at New York’s LaGuardia Airport and Washington’s Ronald Reagan National Airport versus when the Company first began service to these airports in recent years. The impact of this prospective change in accounting estimate is immaterial. The aggregate amortization expense for 2014, 2013, and 2012 was $13 million, $19 million, and $25 million, respectively. Estimated aggregate amortization expense for the five succeeding years and thereafter is as follows: 2015 – $11 million, 2016 – $8 million, 2017 – $5 million, 2018 – $5 million, 2019 – $4 million, and thereafter – $27 million.
Revenue recognition | Revenue recognition Tickets sold are initially deferred as Air traffic liability. Passenger revenue is recognized when transportation is provided. Air traffic liability primarily represents tickets sold for future travel dates and estimated refunds and exchanges of tickets sold for past travel dates. 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. A small percentage of tickets (or partial tickets) expire unused. The Company estimates the amount of tickets that expire unused and recognizes such amounts in Passenger revenue using the redemption method based on scheduled flight date. Prior to September 13, 2013, funds associated with tickets in which a passenger did not show up for a flight without canceling were able to be reused on another flight for up to twelve months. On September 13, 2013, Southwest implemented a No Show policy that applies to nonrefundable fares that are not canceled or changed by a Customer at least ten minutes prior to a flight's scheduled departure. Based on the Company's revenue recognition policy, revenue is now recorded at the flight date for a Customer who does not change his/her itinerary and loses his/her funds. Amounts collected from passengers for ancillary services such as baggage and other fees are generally recognized as Other revenue when the service is provided, which is typically the flight date. The Company's policy is to record revenue for the estimated spoilage of tickets (including partial tickets) once the flight date has passed, under the redemption method. Initial spoilage estimates are routinely adjusted and ultimately finalized once the tickets expire, which is typically twelve months after the original purchase date. Spoilage estimates are based on the Customers' historical travel behavior as well as assumptions about the Customers' future travel behavior. Assumptions used to generate spoilage estimates can be impacted by several factors including, but not limited to: fare increases, fare sales, changes to the Company's ticketing policies, changes to the Company’s refund, exchange and unused funds policies, or economic factors. The Company is also required to collect certain taxes and fees from Customers on behalf of government agencies and remit these back to the applicable governmental entity on a periodic basis. These taxes and fees include U.S. federal transportation taxes, federal security charges, and airport passenger facility charges. These items are collected from Customers at the time they purchase their tickets, but are not included in Passenger revenue. The Company records a liability upon collection from the Customer and relieves the liability when payments are remitted to the applicable governmental agency.
Frequent flyer program | Frequent flyer program The Company records a liability for the estimated incremental cost of providing free travel under its frequent flyer program for all amounts earned from flight activity that are expected to be redeemed for future travel. The estimated incremental cost includes direct passenger costs such as fuel, food, and other operational costs, but does not include any contribution to fixed overhead costs or profit. Southwest also sells frequent flyer points and related services to companies participating in its frequent flyer program. Funds received from the sale of these points are accounted for using the residual method. Under this method, the Company determined the portion of funds received that relate to free travel were currently estimated to be 100 percent of the amount received under the Company's Rapid Reward program as of December 31, 2014. These amounts are deferred and recognized as Passenger revenue when the ultimate free travel awards are flown. For all points sold to business partners that are expected to expire unused, the Company recognizes spoilage in accordance with the redemption method. The Company's consolidated liability associated with the sale of frequent flyer points and/or flight credits, was approximately $1.3 billion and $1.1 billion as of December 31, 2014, and 2013, respectively. This liability is included as part of Air Traffic liability in the Company’s Consolidated Balance Sheet. During fourth quarter 2014, the Company increased the amount of spoilage recorded associated with frequent flyer points sold to business partners as a result of continued monitoring of Member redemption activity and behavior under its Rapid Rewards program. Based on a sufficient amount of historical data and Member attributes observed since the new program was launched in 2011, the Company developed a predictive statistical model to analyze the amount of spoilage expected. In estimating spoilage, the Company takes into account the Member’s past behavior, as well as several factors that are expected to be indicative of the likelihood of future point redemption. These factors include, but are not limited to, tenure with program, points accrued in the program, and whether or not the customer has a co-branded credit card. This change in estimate, which was recorded on a prospective basis, effective October 1, 2014, increased Passenger revenues by approximately $55 million for the quarter and the year ended December 31, 2014. After consideration of profitsharing and taxes, the impact of this change to net income was an increase of $29 million, or $.04 per Basic and Diluted share, for the year ended December 31, 2014. The higher spoilage rate is expected to continue in 2015; however, the precise revenue impact will not be determinable until the actual number of point redemptions for the period is known.
Advertising | Advertising Advertising costs are charged to expense as incurred. Advertising and promotions expense for the years ended December 31, 2014, 2013, and 2012 was $207 million, $208 million, and $223 million, respectively, and is included as a component of Other operating expense in the accompanying Consolidated Statement of Income.
Share-based Employee compensation | Share-based Employee compensation The Company has share-based compensation plans covering certain Employees, including plans covering 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. The fair value of RSUs and PBRSUs is based on the closing price of the Company’s common stock on the date of grant. Outstanding RSUs vest over three years, subject generally to the individual’s continued employment or service. The PBRSUs vest on May 14, 2017, subject to the Company’s performance with respect to a three-year simple average of Return on Invested Capital, before taxes and excluding special items ("ROIC"), for the period beginning on January 1, 2014 and ending on December 31, 2016, and the individual’s continued employment or service. The number of PBRSUs vesting on the vesting date will be interpolated based on the average ROIC for the defined performance period, and ranges from zero PBRSUs at an average ROIC of 12 percent or lower to 200 percent of granted PBRSUs at an average ROIC of 20 percent or higher. The Company recognizes all expense on a straight-line basis over the vesting period, with any changes in expense due to the number of PBRSUs expected to vest being modified on a prospective basis. The Company accounts for share-based compensation utilizing fair value. A portion of the Company’s granted options qualify as incentive stock options for income tax purposes. As such, a tax benefit is not recorded at the time the compensation cost related to the options is recorded for book purposes due to the fact that an incentive stock option does not ordinarily result in a tax benefit unless there is a disqualifying disposition. Grants of non-qualified stock options result in the creation of a deferred tax asset, which is a temporary difference, until the time that the option is exercised. Due to the treatment of incentive stock options for tax purposes, the Company’s effective tax rate from year to year is subject to variability. The Black-Scholes option valuation model was developed for use in estimating the fair value of short-term traded options that have no vesting restrictions and are fully transferable. In addition, option valuation models require the input of subjective assumptions including expected stock price volatility. The Company estimates expected stock price volatility via observations of both historical volatility trends as well as implied future volatility observations as determined by independent third parties.
Fair Value of Financial Instruments | 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 consist primarily of purchased call options, collar structures, call spreads, put spreads, and fixed price swap agreements, and upon proper qualification are accounted for as cash-flow hedges. 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. 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. Also, since there is not a reliable forward market for jet fuel, the Company must estimate the future prices of jet fuel in order to measure the effectiveness of the hedging instruments in offsetting changes to those prices. Forward jet fuel prices are estimated through utilization of a statistical-based regression equation with data from market forward prices of like commodities. This equation is then adjusted for certain items, such as transportation costs, that are stated in the Company’s fuel purchasing contracts with its vendors. For the effective portion of settled fuel hedges, the Company records the associated gains or losses as a component of Fuel and oil expense in the Consolidated Statement of Income. For amounts representing ineffectiveness, as defined, or changes in fair value of derivative instruments for which hedge accounting is not applied, the Company records any gains or losses as a component of Other (gains) losses, net, in the Consolidated Statement of Income. Amounts that are paid or received in connection with the purchase or sale of financial derivative instruments (i.e., premium costs of option contracts) are classified as a component of Other (gains) losses, net, in the Consolidated Statement of Income in the period in which the instrument settles or expires. 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. See Note 10 for further information on hedge accounting and financial derivative instruments. 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. 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 December 31, 2014, 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, commercial paper, 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 10 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.
Software capitalization | 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 typically ranges from 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 $403 million and $357 million at December 31, 2014, and 2013, respectively. Computer software depreciation expense was $122 million, $90 million, and $59 million for the years ended December 31, 2014, 2013, and 2012, respectively, and is included as a component of Depreciation and amortization expense in the accompanying Consolidated Statement of Income.
Income taxes | 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 Consolidated Statement of Income. Amounts recorded for penalties and interest related to uncertain tax positions were immaterial for all years presented.
Concentration risk | Concentration risk Approximately 83 percent of the Company’s full-time equivalent Employees are unionized and are covered by collective bargaining agreements. The Company manages this risk by maintaining positive relationships with its Employees and its Employees’ Representatives. The majority of the Company's unionized Employees, including its Pilots, Mechanics, Ramp, Operations, Provisioning and Freight Agents, Flight Attendants, Material Specialists, Dispatchers, Flight Crew Training Instructors, Flight Simulator Technicians, and Facilities Maintenance Technicians are in discussions on labor agreements or have labor agreements which will become amendable within one year. These Employee groups represent approximately 70 percent of the Company’s full-time equivalent Employees as of December 31, 2014. 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, 2014, the Company operates an all-Boeing fleet, all of which are variations of the Boeing 737. Following the 2011 acquisition of AirTran, the Company also operated a fleet of Boeing 717's, but these aircraft were removed from the Company's operations prior to the end of 2014. See Note 7 for further information. 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 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 or because of a negative perception by the flying public. The Company is also dependent on sole suppliers for aircraft engines and certain other aircraft parts and would, therefore, also be materially adversely impacted in the event of the unavailability of, 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 partnerships, none of which currently extend beyond May 2017. The Company believes the financial benefits generated by the exclusivity aspects of these arrangements outweigh the risks involved with such agreements.
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. Several 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 12. 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 Consolidated Statement of 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 Consolidated Statement of 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 2012, 2013, or 2014. In some situations, an entire commodity type used in hedging may cease to qualify for special hedge accounting treatment Ineffectiveness is inherent in hedging jet fuel with derivative positions based in other crude oil related commodities. Due to the volatility in markets for crude oil and related products, the Company is unable to predict the amount of ineffectiveness each period, including the loss of hedge accounting, which could be determined on a derivative by derivative basis or in the aggregate for a specific commodity. This may result, and has resulted, in increased volatility in the Company’s financial results. Factors that have and may continue to lead to ineffectiveness and unrealized gains and losses on derivative contracts include: significant fluctuation in energy prices, the number of derivative positions the Company holds, significant weather events affecting refinery capacity and the production of refined products, and the volatility of the different types of products the Company uses in hedging. However, even though derivatives may not qualify for hedge accounting, the Company continues to hold the instruments as management believes derivative instruments continue to afford the Company the opportunity to stabilize jet fuel costs. Accounting pronouncements pertaining to derivative instruments and hedging are complex with stringent requirements, including the documentation of a Company hedging strategy, statistical analysis to qualify a commodity for hedge accounting both on a historical and a prospective basis, and strict contemporaneous documentation that is required at the time each hedge is designated by the Company. The Company also examines the effectiveness of each individual hedge and its entire hedging program on a quarterly basis utilizing statistical analysis. This analysis involves utilizing regression and other statistical analyses that compare changes in the price of jet fuel to changes in the prices of the commodities used for hedging purposes All of the Company's fuel derivative instruments and interest rate swaps are subject to agreements that follow the netting guidance in the applicable accounting for derivatives and hedging. The types of derivative instruments the Company has determined are subject to netting requirements in the accompanying Consolidated Balance Sheet are those in which the Company pays or receives cash for transactions with the same counterparty and in the same currency via one net payment or receipt. For cash collateral held by the Company or provided to counterparties, the Company nets such amounts against the fair value of the Company's derivative portfolio by each counterparty. The Company has elected to utilize netting for both its fuel derivative instruments and interest rate swap agreements and also classifies such amounts as either current or noncurrent, based on the net fair value position with each of the Company's counterparties in the Consolidated Balance Sheet. The Company's application of its netting policy associated with cash collateral differs depending on whether its derivative instruments are in a net asset position or a net liability position. If its fuel derivative instruments are in a net asset position with a counterparty, cash collateral amounts held are first netted against current outstanding derivative amounts associated with that counterparty until that balance is zero, and then any remainder is applied against the fair value of noncurrent outstanding derivative instruments. If the Company's fuel derivative instruments are in a net liability position with the counterparty, cash collateral amounts provided are first netted against noncurrent outstanding derivative amounts associated with that counterparty until that balance is zero, and then any remainder is applied against the fair value of current outstanding derivative instruments
Compensation Related Costs | A portion of the Company’s granted options qualify as incentive stock options for income tax purposes. As such, a tax benefit is not recorded at the time the compensation cost related to the options is recorded for book purposes due to the fact that an incentive stock option does not ordinarily result in a tax benefit unless there is a disqualifying disposition. Grants of non-qualified stock options result in the creation of a deferred tax asset, which is a temporary difference, until the time that the option is exercised. Due to the treatment of incentive stock options for tax purposes, the Company’s effective tax rate from year to year is subject to variability.
Employee Retirement Plans | Unrecognized prior service cost is expensed using a straight-line amortization of the cost over the average future service of Employees expected to receive benefits under the plans. Actuarial gains are amortized utilizing the minimum amortization method. The following actuarial assumptions were used to account for the Company’s postretirement benefit plans at December 31, 2014, 2013, and 2012:
|  | 2014 |  | 2013 |  | 2012
Weighted-average discount rate |  | 4.10 | % |  | 5.05 | % |  | 2.90 | %
Assumed healthcare cost trend rate (1) |  | 6.88 | % |  | 7.50 | % |  | 8.00 | %
(1) | The assumed healthcare cost trend rate is assumed to remain at 6.88% for 2015, then decline gradually to 5.00% by 2025 and remain level thereafter.
The assumed healthcare cost trend rates have a significant effect on the amounts reported for the consolidated postretirement plans. A one percent change in all healthcare cost trend rates used in measuring the APBO at December 31, 2014, would have the following effects:
(in millions) |  | 1% increase |  | 1% decrease
Increase (decrease) in total service and interest costs |  | $ | 3 |  |  | $ | (2 | )
Increase (decrease) in the APBO |  | $ | 24 |  |  | $ | (20 | )
The selection of a discount rate is made annually and is selected by the Company based upon comparison of the expected future cash flows associated with the Company’s future payments under its consolidated postretirement obligations to a yield curve created using high quality bonds that closely match those expected future cash flows. This rate decreased during 2014 due to market conditions. The assumed healthcare trend rate is also reviewed at least annually and is determined based upon both historical experience with the Company’s healthcare benefits paid and expectations of how those trends may or may not change in future years.

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- Definition Disclosure of accounting policy for trade and other accounts receivable, and finance, loan and lease receivables, including those classified as held for investment and held for sale. This disclosure may include (1) the basis at which such receivables are carried in the entity's statements of financial position (2) how the level of the valuation allowance for receivables is determined (3) when impairments, charge-offs or recoveries are recognized for such receivables (4) the treatment of origination fees and costs, including the amortization method for net deferred fees or costs (5) the treatment of any premiums or discounts or unearned income (6) the entity's income recognition policies for such receivables, including those that are impaired, past due or placed on nonaccrual status and (7) the treatment of foreclosures or repossessions (8) the nature and amount of any guarantees to repurchase receivables. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6367646&loc=d3e18780-107790 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6378556&loc=d3e10133-111534 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 3-5 -Article 5 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=35738203&loc=d3e4975-111524 + Details
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- Definition Disclosure of accounting policy for revenue recognition. If the entity has different policies for different types of revenue transactions, the policy for each material type of transaction is generally disclosed. If a sales transaction has multiple element arrangements (for example, delivery of multiple products, services or the rights to use assets) the disclosure may indicate the accounting policy for each unit of accounting as well as how units of accounting are determined and valued. The disclosure may encompass important judgment as to appropriateness of principles related to recognition of revenue. The disclosure also may indicate the entity's treatment of any unearned or deferred revenue that arises from the transaction. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6367646&loc=d3e18780-107790 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6367646&loc=d3e18726-107790 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 13 -Section B -Paragraph Question 1 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 605 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SAB TOPIC 13.B.Q1) -URI http://asc.fasb.org/extlink&oid=27012821&loc=d3e214044-122780 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=6367646&loc=d3e18823-107790 + Details
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- Definition Disclosure of accounting policy for stock option and stock incentive plans. This disclosure may include (1) the types of stock option or incentive plans sponsored by the entity (2) the groups that participate in (or are covered by) each plan (3) significant plan provisions and (4) how stock compensation is measured, and the methodologies and significant assumptions used to determine that measurement. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5047-113901 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6367646&loc=d3e18780-107790 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (b),(f) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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