Alaska Air (ALK) 10-Q 2 Nov 18 2018 Q3 Quarterly report Financial data

DOCUMENT AND ENTITY INFORMATION

DOCUMENT AND ENTITY INFORMATION - shares	9 Months Ended
	Sep. 30, 2018	Oct. 31, 2018
Document and Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q3
Entity Registrant Name	ALASKA AIR GROUP, INC.
Entity Central Index Key	766,421
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		123,299,895
Entity Small Business	false
Entity Emerging Growth Company	false

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Current Assets
Cash and cash equivalents	$ 174	$ 194
Marketable securities	1,223	1,427
Total cash and marketable securities	1,397	1,621
Receivables—net	422	341
Inventories and supplies—net	57	57
Prepaid expenses and other current assets	180	133
Total Current Assets	2,056	2,152
Property and Equipment
Aircraft and other flight equipment	7,911	7,559
Other property and equipment	1,322	1,222
Deposits for future flight equipment	429	494
Property and Equipment Total	9,662	9,275
Less accumulated depreciation and amortization	3,167	2,991
Total Property and Equipment—Net	6,495	6,284
Goodwill	1,943	1,943
Intangible assets	128	133
Other noncurrent assets	271	234
Other Assets	2,342	2,310
Total Assets	10,893	10,746
Current Liabilities
Accounts payable	114	120
Accrued wages, vacation and payroll taxes	334	418
Air traffic liability	950	806
Other accrued liabilities	452	400
Deferred revenue, current	693	635
Current portion of long-term debt	345	307
Total Current Liabilities	2,888	2,686
Long-Term Debt, Net of Current Portion	1,684	2,262
Other Liabilities and Credits
Deferred income taxes	494	370
Deferred revenue, noncurrent	1,138	1,090
Obligation for pension and postretirement medical benefits	470	453
Other liabilities	428	425
Other Liabilities and Credits Totals	2,530	2,338
Commitments and Contingencies
Shareholders' Equity
Preferred stock, $0.01 par value, Authorized: 5,000,000 shares, none issued or outstanding	0	0
Common stock, $0.01 par value, Authorized: 400,000,000 shares, Issued: 2018 - 130,786,648 shares; 2017 - 129,903,498 shares, Outstanding: 2018 - 123,360,846 shares; 2017 - 123,060,638 shares	1	1
Capital in excess of par value	224	164
Treasury stock (common), at cost: 2018 - 7,425,802 shares; 2017 - 6,842,860 shares	(556)	(518)
Accumulated other comprehensive loss	(428)	(380)
Retained earnings	4,550	4,193
Total Shareholders' Equity	3,791	3,460
Total Liabilities and Shareholders' Equity	$ 10,893	$ 10,746

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (PARENTHETICALS) - $ / shares	Sep. 30, 2018	Dec. 31, 2017
Stockholders' Equity:
Preferred Stock, par value (usd per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (shares)	5,000,000	5,000,000
Preferred stock, shares issued (shares)	0	0
Preferred stock, shares outstanding (shares)	0	0
Common stock, par value (usd per share)	$ 0.01	$ 0.01
Common stock, shares authorized (shares)	400,000,000	400,000,000
Common stock, shares issued (shares)	130,786,648	129,903,498
Common stock, shares outstanding (shares)	123,360,846	123,060,638
Treasury Stock, Shares (shares)	7,425,802	6,842,860

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Operating Revenues
Total Operating Revenues	$ 2,212	$ 2,110	$ 6,200	$ 5,952
Operating Expenses
Wages and benefits	549	477	1,629	1,397
Variable incentive pay	27	40	104	98
Aircraft fuel, including hedging gains and losses	513	368	1,397	1,051
Aircraft maintenance	107	88	320	271
Aircraft rent	82	70	233	204
Landing fees and other rentals	135	124	371	338
Contracted services	70	76	227	234
Selling expenses	79	92	245	277
Depreciation and amortization	99	95	290	275
Food and beverage service	53	50	158	145
Third-party regional carrier expense	38	30	114	84
Other	141	150	423	421
Special items—merger-related costs	22	23	67	86
Special items—other	0	0	25	0
Total Operating Expenses	1,915	1,683	5,603	4,881
Operating Income	297	427	597	1,071
Nonoperating Income (Expense)
Interest income	11	9	29	25
Interest expense	(22)	(26)	(71)	(77)
Interest capitalized	5	5	14	13
Other—net	(7)	2	(20)	1
Nonoperating Income (Expense) Total	(13)	(10)	(48)	(38)
Income Before Income Tax	284	417	549	1,033
Income tax expense	67	158	135	388
Net Income	$ 217	$ 259	$ 414	$ 645
Basic Earnings Per Share (usd per share)	$ 1.76	$ 2.10	$ 3.36	$ 5.22
Diluted Earnings Per Share (usd per share)	$ 1.75	$ 2.09	$ 3.34	$ 5.19
Shares used for computation:
Basic shares (shares)	123,224	123,467	123,216	123,501
Diluted shares (shares)	123,864	124,220	123,804	124,341
Cash dividend declared per share (usd per share)	$ 0.32	$ 0.3	$ 0.96	$ 0.90
Passenger Revenue [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	$ 2,043	$ 1,958	$ 5,725	$ 5,505
Passenger Revenue [Member] | Passenger [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	2,043	1,958	5,725	5,505
Mileage Plan Revenue [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	267	239	788	719
Mileage Plan Revenue [Member] | Passenger [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	153	134	459	405
Mileage Plan Revenue [Member] | Mileage plan other revenue [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	114	105	329	314
Cargo and Other Revenue [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	55	47	146	133
Cargo and Other Revenue [Member] | Cargo and Freight [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	$ 55	$ 47	$ 146	$ 133

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE OPERATIONS - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement of Comprehensive Income [Abstract]
Net Income	$ 217	$ 259	$ 414	$ 645
Related to marketable securities:
Unrealized holding gain (loss) arising during the period	(2)	1	(19)	5
Reclassification of (gain) loss into Other—net nonoperating income (expense)	2	(1)	5	0
Income tax effect	1	0	4	(2)
Total	1	0	(10)	3
Related to employee benefit plans:
Reclassification of net pension expense into Wages and benefits	7	5	21	16
Income tax effect	(2)	(2)	(5)	(5)
Total	5	3	16	11
Related to interest rate derivative instruments:
Unrealized holding gain (loss) arising during the period	0	0	8	(2)
Reclassification of (gain) loss into Aircraft rent	2	2	3	4
Income tax effect	(1)	(1)	(3)	(1)
Total	1	1	8	1
Other Comprehensive Income	7	4	14	15
Comprehensive Income	$ 224	$ 263	$ 428	$ 660

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Cash flows from operating activities:
Net Income	$ 414	$ 645
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	290	275
Stock-based compensation and other	34	43
Changes in certain assets and liabilities:
Changes in deferred tax provision	122	208
Increase in air traffic liability	144	223
Increase in deferred revenue	106	130
Other—net	(124)	(167)
Net cash provided by operating activities	986	1,357
Property and equipment additions:
Aircraft and aircraft purchase deposits	(349)	(679)
Other flight equipment	(76)	(70)
Other property and equipment	(129)	(92)
Total property and equipment additions, including capitalized interest	(554)	(841)
Purchases of marketable securities	(672)	(1,408)
Sales and maturities of marketable securities	857	1,069
Other investing activities	36	38
Net cash used in investing activities	(333)	(1,142)
Cash flows from financing activities:
Long-term debt payments	(544)	(265)
Common stock repurchases	(37)	(50)
Dividends paid	(118)	(111)
Other financing activities	33	27
Net cash used in financing activities	(666)	(399)
Net increase (decrease) in cash, cash equivalents, and restricted cash	(13)	(184)
Cash, cash equivalents, and restricted cash at beginning of year	197	328
Cash, cash equivalents, and restricted cash at end of the period	184	144
Cash paid during the period for:
Interest (net of amount capitalized)	60	68
Income taxes	$ 0	$ 129

CONDENSED CONSOLIDATED STATEM_4

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2018	Sep. 30, 2017
Statement of Cash Flows [Abstract]
Cash and cash equivalents	$ 174	$ 144
Restricted cash included in Prepaid expenses and other current assets	10	0
Total cash, cash equivalents, and restricted cash at end of the period	$ 184	$ 144

GENERAL AND SUMMARY OF SIGNIFIC

GENERAL AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	9 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
GENERAL AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	GENERAL AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Organization and Basis of Presentation The condensed consolidated financial statements include the accounts of Air Group, or the Company, and its primary subsidiaries, Alaska (including Virgin America) and Horizon. Our condensed consolidated financial statements also include McGee Air Services, a ground services subsidiary of Alaska. The Company conducts substantially all of its operations through these subsidiaries. All significant intercompany balances and transactions have been eliminated. These financial statements have been prepared in accordance with accounting principles generally accepted in the United States (GAAP) for interim financial information. Consistent with these requirements, this Form 10-Q does not include all the information required by GAAP for complete financial statements. It should be read in conjunction with the consolidated financial statements and accompanying notes in the Form 10-K for the year ended December 31, 2017 . In the opinion of management, all adjustments have been made that are necessary to fairly present the Company’s financial position as of September 30, 2018 and the results of operations for the three and nine months ended September 30, 2018 and 2017 . Such adjustments were of a normal recurring nature. Certain reclassifications have been made to prior year financial statements to conform to classifications used in the current year. In preparing these statements, the Company is required to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent liabilities, as well as the reported amounts of revenues and expenses. Due to seasonal variations in the demand for air travel, the volatility of aircraft fuel prices, changes in global economic conditions, changes in the competitive environment and other factors, operating results for the three and nine months ended September 30, 2018 are not necessarily indicative of operating results for the entire year. Recently Issued Accounting Pronouncements In February 2016, the FASB issued ASU 2016-02, "Leases (Topic 842)," which requires lessees to recognize assets and liabilities for leases currently classified as operating leases. Under the new standard, a lessee will recognize a liability on the balance sheet representing the lease payments owed, and a right-of-use asset representing its right to use the underlying asset for the lease term. For leases with a term of 12 months or less, a lessee is permitted to make an accounting policy election not to recognize lease assets and lease liabilities. In July 2018, the FASB issued ASU 2018-11, "Targeted Improvements - Leases (Topic 842)" which amended Topic 842 to provide companies an alternative transition method which would not require adjusting comparative period financial information. The Company plans to utilize this alternative transition method, and will record a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. The new standard is effective for the Company on January 1, 2019. The Company will not early adopt the standard. At this time, the Company believes the most significant impact to the financial statements from the new lease accounting standard will relate to the recording of a right-of-use asset and related liability associated with leased aircraft. The Company does not expect the new standard to have a material impact on the pattern or amount of expense recognized for aircraft leases on the income statement. Other leases, including airports and real estate, equipment, software and other miscellaneous leases continue to be assessed. In November 2016, the FASB issued ASU 2016-18, "Statement of Cash Flows—Restricted Cash (Topic 230)" related to the presentation of restricted cash on the statement of cash flows, and within the accompanying footnotes. The Company adopted the standard effective January 1, 2018. In August 2017, the FASB issued ASU 2017-12, "Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities." The ASU expands the activities that qualify for hedge accounting and simplifies the rules for reporting hedging relationships. The ASU is effective for the Company beginning January 1, 2019, and is required to be adopted using the modified retrospective approach. In February 2018, the FASB issued ASU 2018-02, "Income Statement—Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income." The standard allows a reclassification from accumulated other comprehensive income (AOCI) to retained earnings for stranded tax effects resulting from the Tax Cuts and Jobs Act. The amount of the reclassification is the difference between the amount initially recorded directly to other comprehensive income at the previously enacted U.S. federal corporate income tax rate that remains in AOCI and the amount that would have been recorded directly to other comprehensive income using the newly enacted U.S. federal income tax rate. The standard is effective for interim and annual reporting periods beginning after December 15, 2018, and early adoption is permitted. The Company elected to early adopt the standard effective January 1, 2018. As a result, retained earnings increased approximately $62 million in 2018 due to the reclassification of tax effects in AOCI recorded in prior periods at previously enacted tax rates.

RECENTLY ADOPTED ACCOUNTING PRO

RECENTLY ADOPTED ACCOUNTING PRONOUNCEMENTS	9 Months Ended
	Sep. 30, 2018
Accounting Changes and Error Corrections [Abstract]
RECENTLY ADOPTED ACCOUNTING PRONOUNCEMENTS	RECENTLY ADOPTED ACCOUNTING PRONOUNCEMENTS Revenue Recognition and Retirement Benefits Accounting Standards In May 2014, the FASB issued ASU 2014-09 , "Revenue from Contracts with Customers (Topic 606)." The Company adopted the new standard as of January 1, 2018, utilizing a full retrospective transition method. Adoption of the new standard resulted in changes to accounting policies for revenue recognition related to frequent flyer activity, certain ancillary revenues such as change fees, air traffic liabilities, and sales and marketing expenses. As a result of adoption, the Company also changed certain financial statement line item disclosure captions. See Note 3 for a discussion of the impact of this standard. Although less significant, in March 2017 the FASB issued ASU 2017-07, "Compensation - Retirement Benefits (Topic 715)," which requires the Company to present the service cost component of net periodic benefit cost as Wages and benefits in the statement of operations. The Company adopted the new standard as of January 1, 2018, utilizing a full retrospective transition method. Under this new standard, all components of net periodic benefit cost are presented in Nonoperating income (expense), except service cost, which remains in Wages and benefits. Certain line item captions on the balance sheet and statement of operations changed as a result of the newly implemented standards. Accordingly, historical financial information presented below as reported has been presented using the new captions. The cumulative impact to retained earnings at January 1, 2016 as a result of the new revenue recognition standard was $171 million . Below are the impacts of these newly adopted accounting standards to the financial statements. Condensed consolidated statement of operations for the three and nine months ended September 30, 2017 (in millions): Three Months Ended September 30, 2017 Nine Months Ended September 30, 2017 Adjustments Adjustments As Reported Revenue Recognition Retirement Benefits As Adjusted As Reported Revenue Recognition Retirement Benefits As Adjusted Operating Revenues Passenger Revenue $ 1,824 $ 134 $ — $ 1,958 $ 5,115 $ 390 $ — $ 5,505 Mileage plan other revenue 122 (17 ) — 105 369 (55 ) — 314 Cargo and other revenue 174 (127 ) — 47 487 (354 ) — 133 Total Operating Revenue 2,120 (10 ) — 2,110 5,971 (19 ) — 5,952 Operating Expenses Wages and benefits 475 — 2 477 1,392 — 5 1,397 Selling expenses 91 1 — 92 269 8 — 277 Special items—merger-related costs 24 (1 ) — 23 88 (2 ) — 86 All other operating expenses 1,091 — — 1,091 3,121 — — 3,121 Total Operating Expenses 1,681 — 2 1,683 4,870 6 5 4,881 Operating Income 439 (10 ) (2 ) 427 1,101 (25 ) (5 ) 1,071 Nonoperating Income (Expense) Other—net — — 2 2 (4 ) — 5 1 All other nonoperating income (expense) (12 ) — — (12 ) (39 ) — — (39 ) (12 ) — 2 (10 ) (43 ) — 5 (38 ) Income (loss) before income tax 427 (10 ) — 417 1,058 (25 ) — 1,033 Income tax expense (benefit) 161 (3 ) — 158 397 (9 ) — 388 Net Income (Loss) $ 266 $ (7 ) $ — $ 259 $ 661 $ (16 ) $ — $ 645 Condensed consolidated statement of cash flows for the nine months ended September 30, 2017 (in millions): Nine Months Ended September 30, 2017 As Reported Adjustments - Revenue Recognition As Adjusted Cash flows from operating activities: Net income $ 661 $ (16 ) $ 645 Adjustments to reconcile net income to net cash provided by operating activities: Depreciation and amortization 275 — 275 Stock-based compensation and other 43 — 43 Changes in certain assets and liabilities: Changes in deferred tax provision 217 (9 ) 208 Increase in air traffic liability 254 (31 ) 223 Increase in deferred revenue 46 84 130 Other—net (139 ) (28 ) (167 ) Net cash provided by operating activities 1,357 — 1,357 Net cash used in investing activities (1,142 ) — (1,142 ) Net cash used in financing activities (399 ) — (399 ) Net increase (decrease) in cash and cash equivalents (184 ) — (184 ) Cash and cash equivalents at beginning of year 328 — 328 Cash and cash equivalents at end of the period $ 144 $ — $ 144

REVENUE FROM CONTRACTS WITH CUS

REVENUE FROM CONTRACTS WITH CUSTOMERS	9 Months Ended
	Sep. 30, 2018
Revenue Recognition [Abstract]
REVENUE FROM CONTRACTS WITH CUSTOMERS	REVENUE Ticket revenue is recorded as Passenger revenue, and represents the primary source of the Company's revenue. Also included in Passenger revenue are passenger ancillary revenues such as bag fees, on-board food and beverage, ticket change fees, and certain revenue from the frequent flyer program. Mileage Plan™ other revenue includes brand and marketing revenue from our affinity credit card and other partners and certain interline frequent flyer revenue, net of commissions. Cargo and other revenue includes freight and mail revenue, and to a lesser extent, other ancillary revenue products such as lounge membership and certain commissions. The Company disaggregates revenue by segment in Note 9 . The level of detail within the Company’s statements of operations, segment disclosures, and in this footnote depict the nature, amount, timing and uncertainty of revenue and how cash flows are affected by economic and other factors. Passenger Ticket and Ancillary Services Revenue The primary performance obligation on a typical passenger ticket is to provide air travel to the Company’s passenger. Ticket revenue is collected in advance of travel and recorded as Air Traffic Liability (ATL) on the consolidated balance sheets. The Company satisfies its performance obligation and recognizes ticket revenue on each flight segment when the transportation is provided. Ancillary passenger revenues relate to items such as checked-bag fees, ticket change fees, and on-board food and beverage sales, all of which are provided at time of flight. As such, the obligation to perform these services is satisfied at the time of travel and is recorded with ticket revenue in Passenger revenue. Revenue is also recognized for tickets that are expected to expire unused, a concept referred to as “passenger ticket breakage.” Passenger ticket breakage is recorded at the flight date using estimates made at the time of sale based on the Company’s historical experience of expired tickets, and other facts such as program changes and modifications. In addition to selling tickets on its own marketed flights, the Company has interline agreements with partner airlines under which it sells multi-city tickets with one or more segments of the trip flown by a partner airline, or it operates a connecting flight sold by a partner airline. Each segment in a connecting flight represents a separate performance obligation. Revenue on segments sold and operated by the Company is recognized as Passenger revenue in the gross amount of the allocated ticket price when the travel occurs, while the commission paid to the partner airline is recognized as a selling expense when the related transportation is provided. Revenue on segments operated by a partner airline is deferred for the full amount of the consideration received at the time the ticket is sold and, once the segment has been flown the Company records the net amount, after compensating the partner airline, as Cargo and other revenue. A portion of revenue from the Mileage Plan™ program is recorded in Passenger revenue. As members are awarded mileage credits on flown tickets, these credits become a distinct performance obligation for the Company. The Company allocates the transaction price to each performance obligation identified in a passenger ticket contract on a relative standalone selling price basis. The standalone selling price for loyalty mileage credits issued is discussed in the Loyalty Mileage Credits section of this Note below. The amount allocated to the mileage credits is deferred on the balance sheet. Once a member travels using a travel award redeemed with mileage credits on one of the Company's airline carriers, the revenue associated with those mileage credits is recorded as Passenger revenue. Taxes collected from passengers, including transportation excise taxes, airport and security fees and other fees, are recorded on a net basis within passenger revenue in the consolidated statements of operations. Passenger revenue recognized in the condensed consolidated statements of operations (in millions): Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 Passenger ticket revenue, including ticket breakage and net of taxes and fees $ 1,744 $ 1,683 $ 4,865 $ 4,709 Passenger ancillary revenue 146 141 401 391 Mileage Plan TM passenger revenue 153 134 459 405 Total passenger revenue $ 2,043 $ 1,958 $ 5,725 $ 5,505 As passenger tickets and related ancillary services are primarily sold via credit cards, certain amounts due from credit card processors are recorded as airline traffic receivables. These credit card receivables and receivables from our affinity credit card partner represent the majority of the receivables balance on the Balance Sheet. For performance obligations with performance periods of less than one year, GAAP provides a practical expedient that allows the Company not to disclose the transaction price allocated to remaining performance obligations and the timing of related revenue recognition. As passenger tickets expire one year from ticketing, the Company elected to apply this practical expedient for tickets unused or not exchanged. Mileage Plan™ Loyalty Program Loyalty mileage credits The Company’s Mileage Plan™ loyalty program provides frequent flyer travel awards to program members based upon accumulated loyalty mileage credits. Mileage credits are earned through travel, purchases using the Mileage Plan™ co-branded credit card and purchases from other participating partners. The program has a 24-month expiration period for unused mileage credits from the month of last account activity. The Company offers redemption of mileage credits through free, discounted or upgraded air travel on Alaska flights or on one of its 15 airline partners, as well as redemption at partner hotels. The Company uses a relative standalone selling price allocation to allocate consideration to material performance obligations in contracts with customers that include loyalty mileage credits. As directly observable selling prices for mileage credits are not available, the Company determines the standalone selling price of mileage credits primarily using actual ticket purchase prices for similar tickets flown, adjusted for the likelihood of redemption, or breakage. In determining similar tickets flown, the Company considers current market prices, class of service, type of award, and other factors. For mileage credits accumulated through travel on partner airlines, the Company uses actual consideration received from the partners. Revenue related to air transportation is deferred in the amount of the relative standalone selling price allocated to the mileage credits as they are issued. The Company satisfies its performance obligation when the mileage credits are redeemed and the related air transportation is delivered. The Company estimates breakage for the portion of mileage credits not expected to be redeemed using a statistical analysis of historical data, including actual mileage credits expiring, slow-moving and low-credit accounts, among other factors. The breakage rate for the three and nine months ended September 30, 2018 and 2017 was 17.4% . The Company reviews the breakage rate used on an annual basis. Co-brand credit card agreement and other In addition to mileage credits, the co-brand credit card agreement, referred to herein as the Agreement, also includes performance obligations for waived bag fees, Companion Fare™ offers to purchase an additional ticket at a discount, marketing, and the use of intellectual property including the brand (unlimited access to the use of the Company’s brand and frequent flyer member lists), which is the predominant element in the Agreement. The affinity card bank partner is the customer for some elements, including the brand and marketing, while the Mileage Plan™ member is the customer for other elements such as mileage credits, bag waivers, and Companion Fares. At the inception of the Agreement, management estimated the selling price of each of the performance obligations. The objective was to determine the price at which a sale would be transacted if the product or service was sold on a stand-alone basis. The Company determined its best estimate of selling price for each element by considering multiple inputs and methods including, but not limited to, the estimated selling price of comparable travel, discounted cash flows, brand value, published selling prices, number of miles awarded and number of miles redeemed. The Company estimated the selling prices and volumes over the term of the Agreement in order to determine the allocation of proceeds to each of the multiple deliverables. The estimates of the standalone selling prices of each element do not change subsequent to the original valuation of the contract unless the contract is materially modified, but the allocation between elements may change based upon the actual and updated projected volumes of each element delivered during the term of the contract. Consideration received from the bank is variable and is primarily from consumer spend on the card, among other items. The Company allocates consideration to each of the performance obligations, including mileage credits, waived bag fees, Companion Fares, and brand and marketing, using their relative standalone selling price. Because the performance obligation related to providing use of intellectual property including the brand is satisfied over time, it is recognized in Mileage Plan TM other revenue in the period that those elements are sold. The Company records passenger revenue related to the air transportation and certificates for discounted companion travel when the transportation is delivered. In contracts with non-bank partners, the Company has identified two performance obligations in most cases - travel and brand. Revenue is recognized using the residual method, where the travel performance obligation is deferred until transportation is provided in the amount of the estimated standalone selling price of the ticket, less breakage. The residual amount, if any, is recognized as commission revenue when the brand element is sold. Mileage credit sales recorded under the residual approach are immaterial to the overall program. Interline loyalty The Company has interline arrangements with certain airlines whereby its members may earn and redeem Mileage Plan™ credits on those airlines, and members of a partner airline’s loyalty program may earn and redeem frequent flyer program credits on Alaska. When a Mileage Plan™ member earns credits on a partner airline, the partner airline remits a contractually-agreed upon fee to the Company which is deferred until credits are redeemed. When a Mileage Plan™ member redeems credits on a partner airline, the Company pays a contractually agreed upon fee to the other airline, which offsets the revenue recognized associated with the award travel. When a member of a partner airline redeems frequent flyer credits on Alaska, the partner airline remits a contractually-agreed upon amount to the Company, recognized as Passenger revenue upon travel. If the partner airline’s member earns frequent flyer program credits on an Alaska flight, the Company remits a contractually-agreed upon fee to the partner airline and records a commission expense. Mileage Plan™ revenue included in the condensed consolidated statements of operations (in millions): Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 Passenger revenue $ 153 $ 134 $ 459 $ 405 Mileage Plan TM other revenue 114 105 329 314 Total Mileage Plan™ revenue $ 267 $ 239 $ 788 $ 719 Mileage Plan™ other revenue is primarily brand and marketing revenue from our affinity card products. Cargo and Other The Company provides freight and mail services (cargo). The majority of cargo services are provided to commercial businesses and the United States Postal Service. The Company satisfies cargo service performance obligations and recognizes revenue when the shipment arrives at its final destination or is transferred to a third-party carrier for delivery. The Company also earns other revenue for lounge memberships, hotel and car commissions, and certain other immaterial items not intrinsically tied to providing air travel to passengers. Revenue is recognized when these services are rendered and recorded as Cargo and other revenue. The transaction price for Cargo and other revenue is the price paid by the customer. Cargo and other revenue included in the condensed consolidated statements of operations (in millions): Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 Cargo revenue $ 36 $ 32 $ 96 $ 88 Other revenue 19 15 50 45 Total Cargo and other revenue $ 55 $ 47 $ 146 $ 133 Air Traffic Liability and Deferred Revenue Passenger ticket and ancillary services liabilities Air traffic liability included on the condensed consolidated balance sheets represents the remaining obligation associated with passenger tickets and ancillary services. The air traffic liability balance fluctuates with seasonal travel patterns. The Company recognized Passenger revenue of $27 million and $23 million from the prior year-end air traffic liability balance for the three months ended September 30, 2018 and 2017 , and $540 million and $543 million for the nine months ended September 30, 2018 and 2017 . Mileage Plan TM liabilities The total deferred revenue liability included on the condensed consolidated balance sheets represents the remaining transaction price that has been allocated to Mileage Plan TM performance obligations not yet satisfied by the Company. In general, the current amounts will be recognized as revenue within 12 months and the long-term amounts will be recognized as revenue over, on average, a period of approximately three to four years. This period of time represents the average time that members have historically taken to earn and redeem miles. The Company records a receivable for amounts due from the bank partner and from other partners as mileage credits are sold until the payments are collected. The Company had $106 million of such receivables as of September 30, 2018 and $101 million as of December 31, 2017 . Mileage credits are combined in one homogeneous pool and are not specifically identifiable. As such, loyalty revenues disclosed earlier in this Note are comprised of miles that were part of the deferred revenue and liabilities balances at the beginning of the period and miles that were issued during the period. The table below presents a roll forward of the total frequent flyer liability (in millions): Nine Months Ended September 30, 2018 2017 Total Deferred Revenue balance at January 1 $ 1,725 $ 1,534 Travel miles and companion certificate redemption - Passenger revenue (459 ) (405 ) Miles redeemed on partner airlines - Other revenue (66 ) (54 ) Increase in liability for mileage credits issued 631 586 Total Deferred Revenue balance at September 30 $ 1,831 $ 1,661 Selling Costs Certain costs such as credit card fees, travel agency and other commissions paid, as well as Global Distribution Systems (GDS) booking fees are incurred when the Company sells passenger tickets and ancillary services in advance of the travel date. The Company defers such costs and recognizes them as expenses when the travel occurs. Prepaid expense recorded on the consolidated balance sheets for such costs was $27 million and $24 million as of September 30, 2018 and December 31, 2017 . The Company recorded related expense on the condensed consolidated statement of operations of $57 million and $61 million for the three months ended September 30, 2018 and 2017 , and $166 million and $183 million for the nine months ended September 30, 2018 and 2017 .

FAIR VALUE MEASUREMENTS

FAIR VALUE MEASUREMENTS	9 Months Ended
	Sep. 30, 2018
Fair Value Disclosures [Abstract]
FAIR VALUE MEASUREMENTS	FAIR VALUE MEASUREMENTS In determining fair value, there is a three-level hierarchy based on the reliability of the inputs used. Level 1 refers to fair values based on quoted prices in active markets for identical assets or liabilities. Level 2 refers to fair values estimated using significant other observable inputs and Level 3 refers to fair values estimated using significant unobservable inputs. Fair Value of Financial Instruments on a Recurring Basis As of September 30, 2018 , total cost basis for all marketable securities was $1.2 billion . There were no significant differences between the cost basis and fair value of any individual class of marketable securities. Fair values of financial instruments on the consolidated balance sheet (in millions): September 30, 2018 Level 1 Level 2 Total Assets Marketable securities U.S. government and agency securities $ 338 $ — $ 338 Foreign government bonds — 29 29 Asset-backed securities — 209 209 Mortgage-backed securities — 79 79 Corporate notes and bonds — 559 559 Municipal securities — 9 9 Total Marketable securities 338 885 1,223 Derivative instruments Fuel hedge—call options — 54 54 Interest rate swap agreements — 15 15 Total Assets $ 338 $ 954 $ 1,292 Liabilities Derivative instruments Interest rate swap agreements — (3 ) (3 ) Total Liabilities $ — $ (3 ) $ (3 ) December 31, 2017 Level 1 Level 2 Total Assets Marketable securities U.S. government and agency securities $ 328 $ — $ 328 Foreign government bonds — 43 43 Asset-backed securities — 209 209 Mortgage-backed securities — 99 99 Corporate notes and bonds — 726 726 Municipal securities — 22 22 Total Marketable securities 328 1,099 1,427 Derivative instruments Fuel hedge—call options — 22 22 Interest rate swap agreements — 9 9 Total Assets $ 328 $ 1,130 $ 1,458 Liabilities Derivative instruments Interest rate swap agreements — (8 ) (8 ) Total Liabilities $ — $ (8 ) $ (8 ) The Company uses both the market and income approach to determine the fair value of marketable securities. U.S. government securities are Level 1 as the fair value is based on quoted prices in active markets. Foreign government bonds, asset-backed securities, mortgage-backed securities, corporate notes and bonds, and municipal securities are Level 2 as the fair value is based on standard valuation models that are calculated based on observable inputs such as quoted interest rates, yield curves, credit ratings of the security and other observable market information. The Company uses the market approach and the income approach to determine the fair value of derivative instruments. The fair value for fuel hedge call options is determined utilizing an option pricing model based on inputs that are readily available in active markets or can be derived from information available in active markets. In addition, the fair value considers the exposure to credit losses in the event of non-performance by counterparties. Interest rate swap agreements are Level 2 as the fair value of these contracts is determined based on the difference between the fixed interest rate in the agreements and the observable LIBOR-based interest forward rates at period end multiplied by the total notional value. Activity and Maturities for Marketable Securities Unrealized losses from marketable securities are primarily attributable to changes in interest rates. Management does not believe any unrealized losses represent other-than-temporary impairments based on its evaluation of available information as of September 30, 2018 . Maturities for marketable securities (in millions): September 30, 2018 Cost Basis Fair Value Due in one year or less $ 126 $ 126 Due after one year through five years 1,094 1,072 Due after five years through 10 years 26 25 Total $ 1,246 $ 1,223 Fair Value of Other Financial Instruments The Company uses the following methods and assumptions to determine the fair value of financial instruments that are not recognized at fair value as described below. Cash, Cash Equivalents and Restricted Cash : Cash equivalents consist of highly liquid investments with original maturities of three months or less, such as money market funds, commercial paper and certificates of deposit. They are carried at cost, which approximates fair value. The Company's restricted cash balances are primarily used to guarantee various letters of credit, self-insurance programs or other contractual rights. Restricted cash consists of highly liquid securities with original maturities of three months or less. They are carried at cost, which approximates fair value. Debt : Debt assumed in the acquisition of Virgin America was subject to a non-recurring fair valuation adjustment as part of purchase price accounting. The adjustment is amortized over the life of the associated debt. All other fixed-rate debt is carried at cost. To estimate the fair value of all fixed-rate debt as of September 30, 2018 , the Company uses the income approach by discounting cash flows using borrowing rates for comparable debt over the remaining life of the outstanding debt. The estimated fair value of the fixed-rate debt is Level 3 as certain inputs used are unobservable. Fixed-rate debt on the consolidated balance sheet and the estimated fair value of long-term fixed-rate debt is as follows (in millions): September 30, 2018 December 31, 2017 Fixed-rate debt at cost $ 703 $ 956 Non-recurring purchase price accounting fair value adjustment 3 3 Total fixed-rate debt $ 706 $ 959 Estimated fair value $ 700 $ 959 Assets and Liabilities Measured at Fair Value on Nonrecurring Basis Certain assets and liabilities are recognized or disclosed at fair value on a nonrecurring basis, including property, plant and equipment, goodwill, and intangible assets. These assets are subject to fair valuation when there is evidence of impairment. No material impairment charges were taken in the three and nine months ended September 30, 2018 and September 30, 2017 .

LONG-TERM DEBT

LONG-TERM DEBT	9 Months Ended
	Sep. 30, 2018
Debt Disclosure [Abstract]
LONG-TERM DEBT	LONG-TERM DEBT Long-term debt obligations on the consolidated balance sheet (in millions): September 30, 2018 December 31, 2017 Fixed-rate notes payable due through 2028 $ 706 $ 959 Variable-rate notes payable due through 2028 1,335 1,625 Less debt issuance costs (12 ) (15 ) Total debt 2,029 2,569 Less current portion 345 307 Long-term debt, less current portion $ 1,684 $ 2,262 Weighted-average fixed-interest rate 4.1 % 4.2 % Weighted-average variable-interest rate 3.4 % 2.8 % During the nine months ended September 30, 2018 the Company made debt payments of $544 million , including the prepayment of $231 million of debt. At September 30, 2018 long-term debt principal payments for the next five years and thereafter are as follows (in millions): Total Remainder of 2018 $ 123 2019 267 2020 381 2021 363 2022 179 Thereafter 725 Total $ 2,038 Bank Lines of Credit The Company had three credit facilities totaling $516 million as of September 30, 2018 . All three facilities have variable interest rates based on LIBOR plus a specified margin. One credit facility for $250 million expires in June 2021 and is secured by aircraft. The second credit facility increased from $75 million to $116 million in July 2018 . It expires in July 2019 , with a mechanism for annual renewal, and is secured by aircraft. A third credit facility for $150 million expires in March 2022 and is secured by certain accounts receivable, spare engines, spare parts and ground service equipment. The Company has secured letters of credit against the $116 million facility, but has no plans to borrow using either of the two other facilities. All three credit facilities have a requirement to maintain a minimum unrestricted cash and marketable securities balance of $500 million . The Company was in compliance with this covenant at September 30, 2018 .

EMPLOYEE BENEFIT PLANS

EMPLOYEE BENEFIT PLANS	9 Months Ended
	Sep. 30, 2018
Retirement Benefits [Abstract]
EMPLOYEE BENEFIT PLANS	EMPLOYEE BENEFIT PLANS Net periodic benefit costs for qualified defined-benefit plans include the following (in millions): Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 Service cost $ 12 $ 10 $ 36 $ 30 Pension expense included in Wages and benefits 12 10 36 30 Interest cost 20 19 59 55 Expected return on assets (27 ) (27 ) (80 ) (80 ) Amortization of prior service cost (credit) (1 ) (1 ) (1 ) (1 ) Recognized actuarial loss (gain) 9 7 25 20 Pension expense (benefit) included in Nonoperating Income (Expense) $ 1 $ (2 ) $ 3 $ (6 )

COMMITMENTS

COMMITMENTS	9 Months Ended
	Sep. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS	COMMITMENTS AND CONTINGENCIES Future minimum payments for commitments as of September 30, 2018 (in millions): Aircraft Leases Facility Leases Aircraft Commitments (a) Capacity Purchase Agreements (b) Aircraft Maintenance Deposits Remainder of 2018 $ 88 $ 18 $ 378 $ 33 $ 16 2019 349 64 514 138 65 2020 324 56 525 145 68 2021 282 50 558 166 64 2022 265 35 302 174 52 Thereafter 1,070 149 140 1,205 38 Total $ 2,378 $ 372 $ 2,417 $ 1,861 $ 303 (a) Includes non-cancelable contractual commitments for aircraft and engines, buyer furnished equipment, and aircraft maintenance and parts management. (b) Includes all non-aircraft lease costs associated with capacity purchase agreements. Lease Commitments Aircraft lease commitments include future obligations for all of the Company's operating aircraft, as well as aircraft leases operated by third-parties. At September 30, 2018 , the Company had lease contracts for 10 Boeing 737 (B737) aircraft, 61 Airbus aircraft, 9 Bombardier Q400 aircraft, and 32 Embraer 175 (E175) aircraft with SkyWest Airlines, Inc. (SkyWest). The Company has an additional two scheduled lease deliveries of A321neo aircraft through 2019 , as well as three scheduled lease deliveries of E175 aircraft in 2021 to be operated by SkyWest. The Company does not intend to operate the three E175 aircraft currently scheduled for delivery in 2021 , and is working to remove those aircraft from the capacity purchase agreement. All lease contracts have remaining non-cancelable lease terms ranging from 2018 to 2033 . The Company has the option to increase capacity flown by SkyWest with eight additional E175 aircraft with deliveries from 2021 to 2022 . Options to lease are not reflected in the commitments table above. Facility lease commitments primarily include airport and terminal facilities and building leases. Total rent expense for aircraft and facility leases was $165 million and $145 million for the three months ended September 30, 2018 and 2017 , and $455 million and $406 million for the nine months ended September 30, 2018 and 2017 . Aircraft Commitments Aircraft purchase commitments include non-cancelable contractual commitments for aircraft and engines. As of September 30, 2018 , the Company had commitments to purchase 38 B737 aircraft ( 6 B737 NextGen aircraft and 32 B737 MAX aircraft), with deliveries in the remainder of 2018 through 2023 . In the first quarter of 2018 the Company entered into a supplemental agreement with Boeing to defer certain B737 deliveries and to convert 15 MAX8 aircraft orders to MAX9 aircraft orders. The Company also has commitments to purchase 17 E175 aircraft with deliveries in the remainder of 2018 through 2021 and has cancelable purchase commitments for 30 Airbus A320neo aircraft with deliveries from 2022 through 2024 . In addition, the Company has options to purchase 37 B737 aircraft from 2021 through 2024 and 30 E175 aircraft from 2021 through 2023 . The cancelable purchase commitments and option payments are not reflected in the table above. Contingencies The Company is a party to routine litigation matters incidental to its business and with respect to which no material liability is expected. Liabilities for litigation related contingencies are recorded when a loss is determined to be probable and estimable. In 2015, three flight attendants filed a class action lawsuit seeking to represent all Virgin America flight attendants for damages based on alleged violations of California and City of San Francisco wage and hour laws. Two thousand flight attendants were certified as a class in November 2016. The Company believes the claims in this case are without factual and legal merit. In July 2018, the Court granted in part Plaintiffs' motion for summary judgment, finding Virgin America responsible for various damages and penalties sought by the class members. Plaintiffs value these damages and penalties at $85 million , and as of November 1, 2018, moved the Court to enter judgment against Virgin America in that amount. Plaintiffs do not seek monetary or behavioral relief from Alaska Airlines. The Court will render its final judgment in March 2019. The Company will then seek an appellate court ruling that the California laws on which the judgment is based are invalid as applied to national airlines pursuant to the U.S. Constitution and federal law. The Company remains confident that a higher court will respect the federal preemption principles that were enacted to shield inter-state common carriers from a patchwork of state and local wage and hour regulations such as those at issue in this case. This forward-looking statement is based on management's current understanding of the relevant law and facts, and it is subject to various contingencies, including the potential costs and risks associated with litigation and the actions of judges and juries.

SHAREHOLDERS' EQUITY

SHAREHOLDERS' EQUITY	9 Months Ended
	Sep. 30, 2018
Equity [Abstract]
SHAREHOLDERS' EQUITY	SHAREHOLDERS' EQUITY Dividends During the three months ended September 30, 2018 , the Company declared and paid cash dividends of $0.32 per share, or $39 million . During the nine months ended September 30, 2018 , the Company declared and paid cash dividends of $0.96 per share, or $118 million . Common Stock Repurchase In August 2015 , the Board of Directors authorized a $1 billion share repurchase program. As of September 30, 2018 , the Company has repurchased 5.7 million shares for $426 million under this program. Share repurchase activity (in millions, except share amounts): Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 Shares Amount Shares Amount Shares Amount Shares Amount 2015 Repurchase Program—$1 billion 193,203 $ 12 355,415 $ 28 582,942 $ 37 612,095 $ 50 Accumulated Other Comprehensive Loss Components of accumulated other comprehensive loss, net of tax (in millions): September 30, 2018 December 31, 2017 Related to marketable securities $ (17 ) $ (5 ) Related to employee benefit plans (420 ) (376 ) Related to interest rate derivatives 9 1 Total $ (428 ) $ (380 ) The Company elected to early adopt ASU 2018-02 in the first quarter of 2018 . As a result, the Company reclassified approximately $62 million of tax effects in AOCI recorded in prior periods at previously enacted tax rates thus increasing Retained earnings. Earnings Per Share (EPS) Diluted EPS is calculated by dividing net income by the average number of common shares outstanding plus the number of additional common shares that would have been outstanding assuming the exercise of in-the-money stock options and restricted stock units, using the treasury-stock method. For the three and nine months ended September 30, 2018 and 2017 , anti-dilutive shares excluded from the calculation of EPS were not material.

OPERATING SEGMENT INFORMATION

OPERATING SEGMENT INFORMATION	9 Months Ended
	Sep. 30, 2018
Segment Reporting [Abstract]
OPERATING SEGMENT INFORMATION	OPERATING SEGMENT INFORMATION Alaska Air Group has two operating airlines—Alaska (including Virgin America after the single operating certificate was received in January 2018) and Horizon. Each is regulated by the U.S. Department of Transportation’s Federal Aviation Administration. Alaska has CPAs for regional capacity with Horizon, as well as with third-party carriers SkyWest and PenAir, under which Alaska receives all passenger revenues. Under U.S. GAAP, operating segments are defined as components of a business for which there is discrete financial information that is regularly assessed by the Chief Operating Decision Maker (CODM) in making resource allocation decisions. Financial performance for the operating airlines and CPAs is managed and reviewed by the Company's CODM as part of three reportable operating segments: • Mainline - includes scheduled air transportation on Alaska's Boeing or Airbus jet aircraft for passengers and cargo throughout the U.S., and in parts of Canada, Mexico, and Costa Rica. • Regional - includes Horizon's and other third-party carriers’ scheduled air transportation for passengers across a shorter distance network within the U.S. under CPAs. This segment includes the actual revenues and expenses associated with regional flying, as well as an allocation of corporate overhead incurred by Air Group on behalf of the regional operations. • Horizon - includes the capacity sold to Alaska under CPA. Expenses include those typically borne by regional airlines such as crew costs, ownership costs and maintenance costs. The CODM makes resource allocation decisions for these reporting segments based on flight profitability data, aircraft type, route economics and other financial information. The "Consolidating and Other" column reflects Air Group parent company activity, McGee Air Services, consolidating entries and other immaterial business units of the company. The “Air Group Adjusted” column represents a non-GAAP measure that is used by the Company's CODM to evaluate performance and allocate resources. Adjustments are further explained below in reconciling to consolidated GAAP results. Operating segment information is as follows (in millions): Three Months Ended September 30, 2018 Mainline Regional Horizon Consolidating & Other (a) Air Group Adjusted (b) Special Items (c) Consolidated Operating revenues Passenger revenues $ 1,727 $ 316 $ — $ — $ 2,043 $ — $ 2,043 CPA revenues — — 128 (128 ) — — — Mileage Plan other revenue 104 10 — — 114 — 114 Cargo and other 53 — 2 — 55 — 55 Total operating revenues 1,884 326 130 (128 ) 2,212 — 2,212 Operating expenses Operating expenses, excluding fuel 1,126 267 118 (131 ) 1,380 22 1,402 Economic fuel 438 70 — — 508 5 513 Total operating expenses 1,564 337 118 (131 ) 1,888 27 1,915 Nonoperating income (expense) Interest income 15 — — (4 ) 11 — 11 Interest expense (20 ) — (6 ) 4 (22 ) — (22 ) Interest capitalized 4 — 1 — 5 — 5 Other—net (5 ) (2 ) — — (7 ) — (7 ) Total Nonoperating income (expense) (6 ) (2 ) (5 ) — (13 ) — (13 ) Income (loss) before income tax $ 314 $ (13 ) $ 7 $ 3 $ 311 $ (27 ) $ 284 Three Months Ended September 30, 2017 (d) Mainline Regional Horizon Consolidating & Other (a) Air Group Adjusted (b) Special Items (c) Consolidated Operating revenues Passenger revenues $ 1,677 $ 281 $ — $ — $ 1,958 $ — $ 1,958 CPA revenues — — 112 (112 ) — — — Mileage Plan other revenue 97 8 — — 105 — 105 Cargo and other 46 — 1 — 47 — 47 Total operating revenues 1,820 289 113 (112 ) 2,110 — 2,110 Operating expenses Operating expenses, excluding fuel 1,081 219 104 (112 ) 1,292 23 1,315 Economic fuel 328 45 — — 373 (5 ) 368 Total operating expenses 1,409 264 104 (112 ) 1,665 18 1,683 Nonoperating income (expense) Interest income 12 — — (3 ) 9 — 9 Interest expense (25 ) — (4 ) 3 (26 ) — (26 ) Interest capitalized 5 — — — 5 — 5 Other—net 2 — — — 2 — 2 Total Nonoperating income (expense) (6 ) — (4 ) — (10 ) — (10 ) Income (loss) before income tax $ 405 $ 25 $ 5 $ — $ 435 $ (18 ) $ 417 Nine Months Ended September 30, 2018 (in millions) Mainline Regional Horizon Consolidating & Other (a) Air Group Adjusted (b) Special Items (c) Consolidated Operating revenues Passenger revenues $ 4,880 $ 845 $ — $ — $ 5,725 $ — $ 5,725 CPA revenues — — 375 (375 ) — — — Mileage Plan other revenue 301 28 — — 329 — 329 Cargo and other 141 1 4 — 146 — 146 Total operating revenues 5,322 874 379 (375 ) 6,200 — 6,200 Operating expenses Operating expenses, excluding fuel 3,392 755 345 (378 ) 4,114 92 4,206 Economic fuel 1,237 190 — — 1,427 (30 ) 1,397 Total operating expenses 4,629 945 345 (378 ) 5,541 62 5,603 Nonoperating income (expense) Interest income 39 — — (10 ) 29 — 29 Interest expense (64 ) — (16 ) 9 (71 ) — (71 ) Interest capitalized 12 — 2 — 14 — 14 Other (9 ) (11 ) — — (20 ) — (20 ) Total Nonoperating income (expense) (22 ) (11 ) (14 ) (1 ) (48 ) — (48 ) Income (loss) before income tax $ 671 $ (82 ) $ 20 $ 2 $ 611 $ (62 ) $ 549 Nine Months Ended September 30, 2017 (d) (in millions) Mainline Regional Horizon Consolidating & Other (a) Air Group Adjusted (b) Special Items (c) Consolidated Operating revenues Passenger revenues $ 4,729 $ 776 $ — $ — $ 5,505 $ — $ 5,505 CPA revenues — — 317 (317 ) — — — Mileage Plan other revenue 291 23 — — 314 — 314 Cargo and other 127 3 3 — 133 — 133 Total operating revenues 5,147 802 320 (317 ) 5,952 — 5,952 Operating expenses Operating expenses, excluding fuel 3,111 625 323 (315 ) 3,744 86 3,830 Economic fuel 924 120 — — 1,044 7 1,051 Total operating expenses 4,035 745 323 (315 ) 4,788 93 4,881 Nonoperating income (expense) Interest income 29 — — (4 ) 25 — 25 Interest expense (72 ) — (9 ) 4 (77 ) — (77 ) Interest capitalized 12 — 1 — 13 — 13 Other 1 — — — 1 — 1 Total Nonoperating income (expense) (30 ) — (8 ) — (38 ) — (38 ) Income (loss) before income tax $ 1,082 $ 57 $ (11 ) $ (2 ) $ 1,126 $ (93 ) $ 1,033 (a) Includes consolidating entries, Air Group parent company, McGee Air Services, and other immaterial business units. (b) The Air Group Adjusted column represents the financial information that is reviewed by management to assess performance of operations and determine capital allocations and does not include certain income and charges. (c) Includes merger-related costs, mark-to-market fuel-hedge accounting charges, and other special items. (d) Certain historical information has been adjusted to reflect the adoption of new accounting standards. Total assets were as follows (in millions): September 30, 2018 December 31, 2017 Mainline $ 14,725 $ 16,663 Horizon 1,037 929 Consolidating & Other (4,869 ) (6,846 ) Consolidated $ 10,893 $ 10,746

GENERAL AND SUMMARY OF SIGNIF_2

GENERAL AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	9 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Organization and Basis of Presentation	Organization and Basis of Presentation The condensed consolidated financial statements include the accounts of Air Group, or the Company, and its primary subsidiaries, Alaska (including Virgin America) and Horizon. Our condensed consolidated financial statements also include McGee Air Services, a ground services subsidiary of Alaska. The Company conducts substantially all of its operations through these subsidiaries. All significant intercompany balances and transactions have been eliminated. These financial statements have been prepared in accordance with accounting principles generally accepted in the United States (GAAP) for interim financial information. Consistent with these requirements, this Form 10-Q does not include all the information required by GAAP for complete financial statements. It should be read in conjunction with the consolidated financial statements and accompanying notes in the Form 10-K for the year ended December 31, 2017 . In the opinion of management, all adjustments have been made that are necessary to fairly present the Company’s financial position as of September 30, 2018 and the results of operations for the three and nine months ended September 30, 2018 and 2017 . Such adjustments were of a normal recurring nature. Certain reclassifications have been made to prior year financial statements to conform to classifications used in the current year. In preparing these statements, the Company is required to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent liabilities, as well as the reported amounts of revenues and expenses. Due to seasonal variations in the demand for air travel, the volatility of aircraft fuel prices, changes in global economic conditions, changes in the competitive environment and other factors, operating results for the three and nine months ended September 30, 2018 are not necessarily indicative of operating results for the entire year.
Recently Issued Accounting Pronouncements	Recently Issued Accounting Pronouncements In February 2016, the FASB issued ASU 2016-02, "Leases (Topic 842)," which requires lessees to recognize assets and liabilities for leases currently classified as operating leases. Under the new standard, a lessee will recognize a liability on the balance sheet representing the lease payments owed, and a right-of-use asset representing its right to use the underlying asset for the lease term. For leases with a term of 12 months or less, a lessee is permitted to make an accounting policy election not to recognize lease assets and lease liabilities. In July 2018, the FASB issued ASU 2018-11, "Targeted Improvements - Leases (Topic 842)" which amended Topic 842 to provide companies an alternative transition method which would not require adjusting comparative period financial information. The Company plans to utilize this alternative transition method, and will record a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. The new standard is effective for the Company on January 1, 2019. The Company will not early adopt the standard. At this time, the Company believes the most significant impact to the financial statements from the new lease accounting standard will relate to the recording of a right-of-use asset and related liability associated with leased aircraft. The Company does not expect the new standard to have a material impact on the pattern or amount of expense recognized for aircraft leases on the income statement. Other leases, including airports and real estate, equipment, software and other miscellaneous leases continue to be assessed. In November 2016, the FASB issued ASU 2016-18, "Statement of Cash Flows—Restricted Cash (Topic 230)" related to the presentation of restricted cash on the statement of cash flows, and within the accompanying footnotes. The Company adopted the standard effective January 1, 2018. In August 2017, the FASB issued ASU 2017-12, "Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities." The ASU expands the activities that qualify for hedge accounting and simplifies the rules for reporting hedging relationships. The ASU is effective for the Company beginning January 1, 2019, and is required to be adopted using the modified retrospective approach. In February 2018, the FASB issued ASU 2018-02, "Income Statement—Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income." The standard allows a reclassification from accumulated other comprehensive income (AOCI) to retained earnings for stranded tax effects resulting from the Tax Cuts and Jobs Act. The amount of the reclassification is the difference between the amount initially recorded directly to other comprehensive income at the previously enacted U.S. federal corporate income tax rate that remains in AOCI and the amount that would have been recorded directly to other comprehensive income using the newly enacted U.S. federal income tax rate. The standard is effective for interim and annual reporting periods beginning after December 15, 2018, and early adoption is permitted. The Company elected to early adopt the standard effective January 1, 2018. As a result, retained earnings increased approximately $62 million in 2018 due to the reclassification of tax effects in AOCI recorded in prior periods at previously enacted tax rates.

RECENTLY ADOPTED ACCOUNTING P_2

RECENTLY ADOPTED ACCOUNTING PRONOUNCEMENTS (Tables)	9 Months Ended
	Sep. 30, 2018
Accounting Changes and Error Corrections [Abstract]
Schedule of New Accounting Pronouncements Impact	Condensed consolidated statement of operations for the three and nine months ended September 30, 2017 (in millions): Three Months Ended September 30, 2017 Nine Months Ended September 30, 2017 Adjustments Adjustments As Reported Revenue Recognition Retirement Benefits As Adjusted As Reported Revenue Recognition Retirement Benefits As Adjusted Operating Revenues Passenger Revenue $ 1,824 $ 134 $ — $ 1,958 $ 5,115 $ 390 $ — $ 5,505 Mileage plan other revenue 122 (17 ) — 105 369 (55 ) — 314 Cargo and other revenue 174 (127 ) — 47 487 (354 ) — 133 Total Operating Revenue 2,120 (10 ) — 2,110 5,971 (19 ) — 5,952 Operating Expenses Wages and benefits 475 — 2 477 1,392 — 5 1,397 Selling expenses 91 1 — 92 269 8 — 277 Special items—merger-related costs 24 (1 ) — 23 88 (2 ) — 86 All other operating expenses 1,091 — — 1,091 3,121 — — 3,121 Total Operating Expenses 1,681 — 2 1,683 4,870 6 5 4,881 Operating Income 439 (10 ) (2 ) 427 1,101 (25 ) (5 ) 1,071 Nonoperating Income (Expense) Other—net — — 2 2 (4 ) — 5 1 All other nonoperating income (expense) (12 ) — — (12 ) (39 ) — — (39 ) (12 ) — 2 (10 ) (43 ) — 5 (38 ) Income (loss) before income tax 427 (10 ) — 417 1,058 (25 ) — 1,033 Income tax expense (benefit) 161 (3 ) — 158 397 (9 ) — 388 Net Income (Loss) $ 266 $ (7 ) $ — $ 259 $ 661 $ (16 ) $ — $ 645 Condensed consolidated statement of cash flows for the nine months ended September 30, 2017 (in millions): Nine Months Ended September 30, 2017 As Reported Adjustments - Revenue Recognition As Adjusted Cash flows from operating activities: Net income $ 661 $ (16 ) $ 645 Adjustments to reconcile net income to net cash provided by operating activities: Depreciation and amortization 275 — 275 Stock-based compensation and other 43 — 43 Changes in certain assets and liabilities: Changes in deferred tax provision 217 (9 ) 208 Increase in air traffic liability 254 (31 ) 223 Increase in deferred revenue 46 84 130 Other—net (139 ) (28 ) (167 ) Net cash provided by operating activities 1,357 — 1,357 Net cash used in investing activities (1,142 ) — (1,142 ) Net cash used in financing activities (399 ) — (399 ) Net increase (decrease) in cash and cash equivalents (184 ) — (184 ) Cash and cash equivalents at beginning of year 328 — 328 Cash and cash equivalents at end of the period $ 144 $ — $ 144

REVENUE FROM CONTRACTS WITH C_2

REVENUE FROM CONTRACTS WITH CUSTOMERS (Tables)	9 Months Ended
	Sep. 30, 2018
Revenue Recognition [Abstract]
Disaggregation of Revenue	Cargo and other revenue included in the condensed consolidated statements of operations (in millions): Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 Cargo revenue $ 36 $ 32 $ 96 $ 88 Other revenue 19 15 50 45 Total Cargo and other revenue $ 55 $ 47 $ 146 $ 133 Mileage Plan™ revenue included in the condensed consolidated statements of operations (in millions): Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 Passenger revenue $ 153 $ 134 $ 459 $ 405 Mileage Plan TM other revenue 114 105 329 314 Total Mileage Plan™ revenue $ 267 $ 239 $ 788 $ 719 Passenger revenue recognized in the condensed consolidated statements of operations (in millions): Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 Passenger ticket revenue, including ticket breakage and net of taxes and fees $ 1,744 $ 1,683 $ 4,865 $ 4,709 Passenger ancillary revenue 146 141 401 391 Mileage Plan TM passenger revenue 153 134 459 405 Total passenger revenue $ 2,043 $ 1,958 $ 5,725 $ 5,505
Contract with Customer Liabilities	The table below presents a roll forward of the total frequent flyer liability (in millions): Nine Months Ended September 30, 2018 2017 Total Deferred Revenue balance at January 1 $ 1,725 $ 1,534 Travel miles and companion certificate redemption - Passenger revenue (459 ) (405 ) Miles redeemed on partner airlines - Other revenue (66 ) (54 ) Increase in liability for mileage credits issued 631 586 Total Deferred Revenue balance at September 30 $ 1,831 $ 1,661

FAIR VALUE MEASUREMENTS (Tables

FAIR VALUE MEASUREMENTS (Tables)	9 Months Ended
	Sep. 30, 2018
Fair Value Disclosures [Abstract]
Activity for Marketable Securities
Investments Classified by Contractual Maturity Date	Maturities for marketable securities (in millions): September 30, 2018 Cost Basis Fair Value Due in one year or less $ 126 $ 126 Due after one year through five years 1,094 1,072 Due after five years through 10 years 26 25 Total $ 1,246 $ 1,223
Fair Value, by Balance Sheet Grouping	Fair values of financial instruments on the consolidated balance sheet (in millions): September 30, 2018 Level 1 Level 2 Total Assets Marketable securities U.S. government and agency securities $ 338 $ — $ 338 Foreign government bonds — 29 29 Asset-backed securities — 209 209 Mortgage-backed securities — 79 79 Corporate notes and bonds — 559 559 Municipal securities — 9 9 Total Marketable securities 338 885 1,223 Derivative instruments Fuel hedge—call options — 54 54 Interest rate swap agreements — 15 15 Total Assets $ 338 $ 954 $ 1,292 Liabilities Derivative instruments Interest rate swap agreements — (3 ) (3 ) Total Liabilities $ — $ (3 ) $ (3 ) December 31, 2017 Level 1 Level 2 Total Assets Marketable securities U.S. government and agency securities $ 328 $ — $ 328 Foreign government bonds — 43 43 Asset-backed securities — 209 209 Mortgage-backed securities — 99 99 Corporate notes and bonds — 726 726 Municipal securities — 22 22 Total Marketable securities 328 1,099 1,427 Derivative instruments Fuel hedge—call options — 22 22 Interest rate swap agreements — 9 9 Total Assets $ 328 $ 1,130 $ 1,458 Liabilities Derivative instruments Interest rate swap agreements — (8 ) (8 ) Total Liabilities $ — $ (8 ) $ (8 ) Fixed-rate debt on the consolidated balance sheet and the estimated fair value of long-term fixed-rate debt is as follows (in millions): September 30, 2018 December 31, 2017 Fixed-rate debt at cost $ 703 $ 956 Non-recurring purchase price accounting fair value adjustment 3 3 Total fixed-rate debt $ 706 $ 959 Estimated fair value $ 700 $ 959

LONG-TERM DEBT (Tables)

LONG-TERM DEBT (Tables)	9 Months Ended
	Sep. 30, 2018
Debt Disclosure [Abstract]
Schedule of Long-term Debt Instruments	Long-term debt obligations on the consolidated balance sheet (in millions): September 30, 2018 December 31, 2017 Fixed-rate notes payable due through 2028 $ 706 $ 959 Variable-rate notes payable due through 2028 1,335 1,625 Less debt issuance costs (12 ) (15 ) Total debt 2,029 2,569 Less current portion 345 307 Long-term debt, less current portion $ 1,684 $ 2,262 Weighted-average fixed-interest rate 4.1 % 4.2 % Weighted-average variable-interest rate 3.4 % 2.8 %
Schedule of Maturities of Long-term Debt	At September 30, 2018 long-term debt principal payments for the next five years and thereafter are as follows (in millions): Total Remainder of 2018 $ 123 2019 267 2020 381 2021 363 2022 179 Thereafter 725 Total $ 2,038

EMPLOYEE BENEFIT PLANS (Tables)

EMPLOYEE BENEFIT PLANS (Tables)	9 Months Ended
	Sep. 30, 2018
Retirement Benefits [Abstract]
Schedule of Net Benefit Costs	Net periodic benefit costs for qualified defined-benefit plans include the following (in millions): Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 Service cost $ 12 $ 10 $ 36 $ 30 Pension expense included in Wages and benefits 12 10 36 30 Interest cost 20 19 59 55 Expected return on assets (27 ) (27 ) (80 ) (80 ) Amortization of prior service cost (credit) (1 ) (1 ) (1 ) (1 ) Recognized actuarial loss (gain) 9 7 25 20 Pension expense (benefit) included in Nonoperating Income (Expense) $ 1 $ (2 ) $ 3 $ (6 )

COMMITMENTS (Tables)

COMMITMENTS (Tables)	9 Months Ended
	Sep. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
Schedule of Future Minimum Rental Payments for Operating Leases and Unrecorded Unconditional Purchase Obligtaions	Future minimum payments for commitments as of September 30, 2018 (in millions): Aircraft Leases Facility Leases Aircraft Commitments (a) Capacity Purchase Agreements (b) Aircraft Maintenance Deposits Remainder of 2018 $ 88 $ 18 $ 378 $ 33 $ 16 2019 349 64 514 138 65 2020 324 56 525 145 68 2021 282 50 558 166 64 2022 265 35 302 174 52 Thereafter 1,070 149 140 1,205 38 Total $ 2,378 $ 372 $ 2,417 $ 1,861 $ 303 (a) Includes non-cancelable contractual commitments for aircraft and engines, buyer furnished equipment, and aircraft maintenance and parts management. (b) Includes all non-aircraft lease costs associated with capacity purchase agreements.

SHAREHOLDERS' EQUITY (Tables)

SHAREHOLDERS' EQUITY (Tables)	9 Months Ended
	Sep. 30, 2018
Equity [Abstract]
Schedule of Treasury Stock by Class	Share repurchase activity (in millions, except share amounts): Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 Shares Amount Shares Amount Shares Amount Shares Amount 2015 Repurchase Program—$1 billion 193,203 $ 12 355,415 $ 28 582,942 $ 37 612,095 $ 50
Schedule of Accumulated Other Comprehensive Income (Loss)	Components of accumulated other comprehensive loss, net of tax (in millions): September 30, 2018 December 31, 2017 Related to marketable securities $ (17 ) $ (5 ) Related to employee benefit plans (420 ) (376 ) Related to interest rate derivatives 9 1 Total $ (428 ) $ (380 )

OPERATING SEGMENT INFORMATION (

OPERATING SEGMENT INFORMATION (Tables)	9 Months Ended
	Sep. 30, 2018
Segment Reporting [Abstract]
Schedule of Segment Reporting Information, by Segment	Operating segment information is as follows (in millions): Three Months Ended September 30, 2018 Mainline Regional Horizon Consolidating & Other (a) Air Group Adjusted (b) Special Items (c) Consolidated Operating revenues Passenger revenues $ 1,727 $ 316 $ — $ — $ 2,043 $ — $ 2,043 CPA revenues — — 128 (128 ) — — — Mileage Plan other revenue 104 10 — — 114 — 114 Cargo and other 53 — 2 — 55 — 55 Total operating revenues 1,884 326 130 (128 ) 2,212 — 2,212 Operating expenses Operating expenses, excluding fuel 1,126 267 118 (131 ) 1,380 22 1,402 Economic fuel 438 70 — — 508 5 513 Total operating expenses 1,564 337 118 (131 ) 1,888 27 1,915 Nonoperating income (expense) Interest income 15 — — (4 ) 11 — 11 Interest expense (20 ) — (6 ) 4 (22 ) — (22 ) Interest capitalized 4 — 1 — 5 — 5 Other—net (5 ) (2 ) — — (7 ) — (7 ) Total Nonoperating income (expense) (6 ) (2 ) (5 ) — (13 ) — (13 ) Income (loss) before income tax $ 314 $ (13 ) $ 7 $ 3 $ 311 $ (27 ) $ 284 Three Months Ended September 30, 2017 (d) Mainline Regional Horizon Consolidating & Other (a) Air Group Adjusted (b) Special Items (c) Consolidated Operating revenues Passenger revenues $ 1,677 $ 281 $ — $ — $ 1,958 $ — $ 1,958 CPA revenues — — 112 (112 ) — — — Mileage Plan other revenue 97 8 — — 105 — 105 Cargo and other 46 — 1 — 47 — 47 Total operating revenues 1,820 289 113 (112 ) 2,110 — 2,110 Operating expenses Operating expenses, excluding fuel 1,081 219 104 (112 ) 1,292 23 1,315 Economic fuel 328 45 — — 373 (5 ) 368 Total operating expenses 1,409 264 104 (112 ) 1,665 18 1,683 Nonoperating income (expense) Interest income 12 — — (3 ) 9 — 9 Interest expense (25 ) — (4 ) 3 (26 ) — (26 ) Interest capitalized 5 — — — 5 — 5 Other—net 2 — — — 2 — 2 Total Nonoperating income (expense) (6 ) — (4 ) — (10 ) — (10 ) Income (loss) before income tax $ 405 $ 25 $ 5 $ — $ 435 $ (18 ) $ 417 Nine Months Ended September 30, 2018 (in millions) Mainline Regional Horizon Consolidating & Other (a) Air Group Adjusted (b) Special Items (c) Consolidated Operating revenues Passenger revenues $ 4,880 $ 845 $ — $ — $ 5,725 $ — $ 5,725 CPA revenues — — 375 (375 ) — — — Mileage Plan other revenue 301 28 — — 329 — 329 Cargo and other 141 1 4 — 146 — 146 Total operating revenues 5,322 874 379 (375 ) 6,200 — 6,200 Operating expenses Operating expenses, excluding fuel 3,392 755 345 (378 ) 4,114 92 4,206 Economic fuel 1,237 190 — — 1,427 (30 ) 1,397 Total operating expenses 4,629 945 345 (378 ) 5,541 62 5,603 Nonoperating income (expense) Interest income 39 — — (10 ) 29 — 29 Interest expense (64 ) — (16 ) 9 (71 ) — (71 ) Interest capitalized 12 — 2 — 14 — 14 Other (9 ) (11 ) — — (20 ) — (20 ) Total Nonoperating income (expense) (22 ) (11 ) (14 ) (1 ) (48 ) — (48 ) Income (loss) before income tax $ 671 $ (82 ) $ 20 $ 2 $ 611 $ (62 ) $ 549 Nine Months Ended September 30, 2017 (d) (in millions) Mainline Regional Horizon Consolidating & Other (a) Air Group Adjusted (b) Special Items (c) Consolidated Operating revenues Passenger revenues $ 4,729 $ 776 $ — $ — $ 5,505 $ — $ 5,505 CPA revenues — — 317 (317 ) — — — Mileage Plan other revenue 291 23 — — 314 — 314 Cargo and other 127 3 3 — 133 — 133 Total operating revenues 5,147 802 320 (317 ) 5,952 — 5,952 Operating expenses Operating expenses, excluding fuel 3,111 625 323 (315 ) 3,744 86 3,830 Economic fuel 924 120 — — 1,044 7 1,051 Total operating expenses 4,035 745 323 (315 ) 4,788 93 4,881 Nonoperating income (expense) Interest income 29 — — (4 ) 25 — 25 Interest expense (72 ) — (9 ) 4 (77 ) — (77 ) Interest capitalized 12 — 1 — 13 — 13 Other 1 — — — 1 — 1 Total Nonoperating income (expense) (30 ) — (8 ) — (38 ) — (38 ) Income (loss) before income tax $ 1,082 $ 57 $ (11 ) $ (2 ) $ 1,126 $ (93 ) $ 1,033 (a) Includes consolidating entries, Air Group parent company, McGee Air Services, and other immaterial business units. (b) The Air Group Adjusted column represents the financial information that is reviewed by management to assess performance of operations and determine capital allocations and does not include certain income and charges. (c) Includes merger-related costs, mark-to-market fuel-hedge accounting charges, and other special items. (d) Certain historical information has been adjusted to reflect the adoption of new accounting standards. Total assets were as follows (in millions): September 30, 2018 December 31, 2017 Mainline $ 14,725 $ 16,663 Horizon 1,037 929 Consolidating & Other (4,869 ) (6,846 ) Consolidated $ 10,893 $ 10,746

GENERAL AND SUMMARY OF SIGNIF_3

GENERAL AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES NARRATIVE (Details) - USD ($) $ in Millions	Jan. 01, 2018	Jan. 01, 2016
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reclassification from AOCI to retained earnings	$ 62
Accounting Standards Update 2014-09 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of new accounting pronouncements		$ 171

RECENTLY ADOPTED ACCOUNTING P_3

RECENTLY ADOPTED ACCOUNTING PRONOUNCEMENTS (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Jan. 01, 2016
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cash and cash equivalents					$ 174	$ 194	$ 144
Cash, cash equivalents, and restricted cash	$ 184	$ 144	$ 197	$ 328	184	197	144
Current Assets
Prepaid expenses and other current assets					180	133
Current Liabilities
Air traffic liability					950	806
Other accrued liabilities					452	400
Deferred revenue, current					693	635
Other Liabilities and Credits
Deferred income taxes					494	370
Deferred revenue, noncurrent					1,138	1,090
Other liabilities					428	425
Shareholders' Equity
Retained earnings					$ 4,550	$ 4,193
Operating Revenues
Total Operating Revenues	2,212	2,110	6,200	5,952
Operating Expenses
Wages and benefits	549	477	1,629	1,397
Selling expenses	79	92	245	277
Special items—merger-related costs	22	23	67	86
All other operating expenses		1,091		3,121
Total Operating Expenses	1,915	1,683	5,603	4,881
Operating Income	297	427	597	1,071
Nonoperating Income (Expense)
Other—net	(7)	2	(20)	1
Nonoperating Income (Expense), Other		(12)		(39)
Nonoperating Income (Expense) Total	(13)	(10)	(48)	(38)
Income Before Income Tax	284	417	549	1,033
Income tax expense	67	158	135	388
Net Income (loss)	217	259	414	645
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	99	95	290	275
Stock-based compensation and other			34	43
Changes in deferred tax provision			122	208
Increase in air traffic liability			144	223
Increase in deferred revenue			106	130
Other—net			(124)	(167)
Net cash provided by operating activities			986	1,357
Net cash used in investing activities			(333)	(1,142)
Net cash used in financing activities			(666)	(399)
Net increase (decrease) in cash, cash equivalents, and restricted cash			(13)	(184)
Cash, cash equivalents, and restricted cash at beginning of year			197	328
Cash, cash equivalents, and restricted cash at end of the period	184	144	184	144
As Reported [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cash, cash equivalents, and restricted cash		144		328			144
Operating Revenues
Mileage plan other revenue		122		369
Total Operating Revenues		2,120		5,971
Operating Expenses
Wages and benefits		475		1,392
Selling expenses		91		269
Special items—merger-related costs		24		88
All other operating expenses		1,091		3,121
Total Operating Expenses		1,681		4,870
Operating Income		439		1,101
Nonoperating Income (Expense)
Other—net		0		(4)
Nonoperating Income (Expense), Other		(12)		(39)
Nonoperating Income (Expense) Total		(12)		(43)
Income Before Income Tax		427		1,058
Income tax expense		161		397
Net Income (loss)		266		661
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization				275
Stock-based compensation and other				43
Changes in deferred tax provision				217
Increase in air traffic liability				254
Increase in deferred revenue				46
Other—net				(139)
Net cash provided by operating activities				1,357
Net cash used in investing activities				(1,142)
Net cash used in financing activities				(399)
Net increase (decrease) in cash, cash equivalents, and restricted cash				(184)
Cash, cash equivalents, and restricted cash at beginning of year				328
Cash, cash equivalents, and restricted cash at end of the period		144		144
Accounting Standards Update 2014-09 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of new accounting pronouncements								$ 171
Accounting Standards Update 2014-09 [Member] | Adjustments [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cash, cash equivalents, and restricted cash		0		0			$ 0
Operating Revenues
Mileage plan other revenue		(17)		(55)
Total Operating Revenues		(10)		(19)
Operating Expenses
Wages and benefits		0		0
Selling expenses		1		8
Special items—merger-related costs		(1)		(2)
All other operating expenses		0		0
Total Operating Expenses		0		6
Operating Income		(10)		(25)
Nonoperating Income (Expense)
Other—net		0		0
Nonoperating Income (Expense), Other		0		0
Nonoperating Income (Expense) Total		0		0
Income Before Income Tax		(10)		(25)
Income tax expense		(3)		(9)
Net Income (loss)		(7)		(16)
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization				0
Stock-based compensation and other				0
Changes in deferred tax provision				(9)
Increase in air traffic liability				(31)
Increase in deferred revenue				84
Other—net				(28)
Net cash provided by operating activities				0
Net cash used in investing activities				0
Net cash used in financing activities				0
Net increase (decrease) in cash, cash equivalents, and restricted cash				0
Cash, cash equivalents, and restricted cash at beginning of year				0
Cash, cash equivalents, and restricted cash at end of the period		0		0
Accounting Standards Update 2017-07 [Member] | Adjustments [Member]
Operating Revenues
Mileage plan other revenue		0		0
Total Operating Revenues		0		0
Operating Expenses
Wages and benefits		2		5
Selling expenses		0		0
Special items—merger-related costs		0		0
All other operating expenses		0		0
Total Operating Expenses		2		5
Operating Income		(2)		(5)
Nonoperating Income (Expense)
Other—net		2		5
Nonoperating Income (Expense), Other		0		0
Nonoperating Income (Expense) Total		2		5
Income Before Income Tax		0		0
Income tax expense		0		0
Net Income (loss)		0		0
Cargo and Freight [Member]
Operating Revenues
Revenue from contract with customer, including assessed taxes	55	47	146	133
Cargo and Freight [Member] | As Reported [Member]
Operating Revenues
Revenue from contract with customer, including assessed taxes		174		487
Cargo and Freight [Member] | Accounting Standards Update 2014-09 [Member] | Adjustments [Member]
Operating Revenues
Revenue from contract with customer, including assessed taxes		(127)		(354)
Cargo and Freight [Member] | Accounting Standards Update 2017-07 [Member] | Adjustments [Member]
Operating Revenues
Revenue from contract with customer, including assessed taxes		0		0
Passenger [Member]
Operating Revenues
Revenue from contract with customer, including assessed taxes	2,043	1,958	5,725	5,505
Passenger [Member] | As Reported [Member]
Operating Revenues
Revenue from contract with customer, including assessed taxes		1,824		5,115
Passenger [Member] | Accounting Standards Update 2014-09 [Member] | Adjustments [Member]
Operating Revenues
Revenue from contract with customer, including assessed taxes		134		390
Passenger [Member] | Accounting Standards Update 2017-07 [Member] | Adjustments [Member]
Operating Revenues
Revenue from contract with customer, including assessed taxes		0		0
Cargo and Other Revenue [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	55	47	146	133
Cargo and Other Revenue [Member] | Cargo and Freight [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	$ 55	$ 47	$ 146	$ 133

REVENUE FROM CONTRACTS WITH C_3

REVENUE FROM CONTRACTS WITH CUSTOMERS - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Passenger Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 2,043	$ 1,958	$ 5,725	$ 5,505
Passenger Revenue [Member] | Passenger ticket revenue, including ticket breakage and net of taxes and fees [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	1,744	1,683	4,865	4,709
Passenger Revenue [Member] | Passenger ancillary revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	146	141	401	391
Passenger Revenue [Member] | Mileage Plan passenger revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	153	134	459	405
Passenger Revenue [Member] | Passenger [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	2,043	1,958	5,725	5,505
Mileage Plan Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	267	239	788	719
Mileage Plan Revenue [Member] | Passenger [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	153	134	459	405
Mileage Plan Revenue [Member] | Mileage plan other revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	114	105	329	314
Cargo and Other Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	55	47	146	133
Cargo and Other Revenue [Member] | Cargo revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	36	32	96	88
Cargo and Other Revenue [Member] | Other revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 19	$ 15	$ 50	$ 45

REVENUE FROM CONTRACTS WITH C_4

REVENUE FROM CONTRACTS WITH CUSTOMERS - Narrative (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018USD ($)	Sep. 30, 2017USD ($)	Sep. 30, 2018USD ($)airline	Sep. 30, 2017USD ($)	Dec. 31, 2017USD ($)
Deferred Revenue Arrangement [Line Items]
Number of airline partners | airline			15
Breakage rate	17.40%	17.40%	17.40%	17.40%
Air traffic liability	$ 950		$ 950		$ 806
Receivable	422		422		341
Contract cost recognized	57	$ 61	166	$ 183
Prepaid Expenses and Other Current Assets [Member]
Deferred Revenue Arrangement [Line Items]
Contract costs	27		27		24
Mileage Plan Revenue [Member]
Deferred Revenue Arrangement [Line Items]
Receivable	106		106		$ 101
Mileage Plan Revenue [Member] | Mileage plan other revenue [Member]
Deferred Revenue Arrangement [Line Items]
Contract liability revenue recognized			(66)	(54)
Passenger Revenue [Member]
Deferred Revenue Arrangement [Line Items]
Contract liability revenue recognized	$ 27	$ 23	$ 540	$ 543

REVENUE FROM CONTRACTS WITH C_5

REVENUE FROM CONTRACTS WITH CUSTOMERS - Contract Liabilities Activity (Details) - Mileage Plan Revenue [Member] - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Change in Contract with Customer, Liability [Roll Forward]
Total Deferred Revenue balance at January 1	$ 1,725	$ 1,534
Increase in liability for mileage credits issued	631	586
Total Deferred Revenue balance at September 30	1,831	1,661
Passenger revenue [Member]
Change in Contract with Customer, Liability [Roll Forward]
Revenue recognized	(459)	(405)
Mileage plan other revenue [Member]
Change in Contract with Customer, Liability [Roll Forward]
Revenue recognized	$ (66)	$ (54)

FAIR VALUE MEASUREMENTS - FAIR

FAIR VALUE MEASUREMENTS - FAIR VALUE OF ASSETS AND LIABILITIES (Details) - Recurring [Member] - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	$ 1,223	$ 1,427
Assets, Fair Value Disclosure	1,292	1,458
Financial and Nonfinancial Liabilities, Fair Value Disclosure	3	8
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	338	328
Assets, Fair Value Disclosure	338	328
Financial and Nonfinancial Liabilities, Fair Value Disclosure	0	0
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	885	1,099
Assets, Fair Value Disclosure	954	1,130
Financial and Nonfinancial Liabilities, Fair Value Disclosure	3	8
Fuel hedge contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative instruments, assets	54	22
Fuel hedge contracts [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative instruments, assets	0	0
Fuel hedge contracts [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative instruments, assets	54	22
Interest rate swaps agreements [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative instruments, assets	15	9
Derivative instruments, liabilities	3	8
Interest rate swaps agreements [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative instruments, assets	0	0
Derivative instruments, liabilities	0	0
Interest rate swaps agreements [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative instruments, assets	15	9
Derivative instruments, liabilities	3	8
U.S. government and agency securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	338	328
U.S. government and agency securities [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	338	328
U.S. government and agency securities [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0	0
Foreign government bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	29	43
Foreign government bonds [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0	0
Foreign government bonds [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	29	43
Asset-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	209	209
Asset-backed securities [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0	0
Asset-backed securities [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	209	209
Mortgage-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	79	99
Mortgage-backed securities [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0	0
Mortgage-backed securities [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	79	99
Corporate notes and bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	559	726
Corporate notes and bonds [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0	0
Corporate notes and bonds [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	559	726
Municipal securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	9	22
Municipal securities [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0	0
Municipal securities [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	$ 9	$ 22

FAIR VALUE MEASUREMENTS - MATU

FAIR VALUE MEASUREMENTS - MATURITIES FOR MARKETABLE SECURITIES (Details) $ in Millions	Sep. 30, 2018USD ($)
Cost Basis
Due in one year or less	$ 126
Due after one year through five years	1,094
Due after five years through 10 years	26
Total	1,246
Fair Value
Due in one year or less	126
Due after one year through five years	1,072
Due after five years through 10 years	25
Total	$ 1,223

FAIR VALUE MEASUREMENTS - LONG-

FAIR VALUE MEASUREMENTS - LONG-TERM DEBT (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Non-recurring purchase price accounting fair value adjustment	$ 3	$ 3
Carrying amount [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fixed rate debt at cost	703	956
Long-term debt	706	959
Fair value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	$ 700	$ 959

LONG-TERM DEBT - SCHEDULE OF LO

LONG-TERM DEBT - SCHEDULE OF LONG-TERM DEBT (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Debt Instrument [Line Items]
Debt Issuance Costs, Net	$ (12)		$ (15)
Total	2,029		2,569
Less current portion	345		307
Long-term debt, less current portion	$ 1,684		$ 2,262
Weighted-average fixed-interest rate	4.10%		4.20%
Weighted-average variable-interest rate	3.40%		2.80%
Long-term debt payments	$ 544	$ 265
Repayments of Debt	231
Fixed rate notes payable due through 2028 [Member]
Debt Instrument [Line Items]
Total	706		$ 959
Variable rate notes payable due through 2028 [Member]
Debt Instrument [Line Items]
Total	$ 1,335		$ 1,625

LONG-TERM DEBT LONG-TERM DEBT -

LONG-TERM DEBT LONG-TERM DEBT - FUTURE PAYMENTS (Details) $ in Millions	Sep. 30, 2018USD ($)
Long-term Debt, Fiscal Year Maturity [Abstract]
Remainder of 2018	$ 123
2,019	267
2,020	381
2,021	363
2,022	179
Thereafter	725
Total	$ 2,038

LONG-TERM DEBT - LINE OF CREDIT

LONG-TERM DEBT - LINE OF CREDIT (Details)	9 Months Ended
	Sep. 30, 2018USD ($)credit_facility	Jul. 30, 2018USD ($)	Jun. 30, 2018USD ($)
Line of Credit Facility [Line Items]
Line of Credit Facility, Number of Credit Facilities | credit_facility	3
Line of Credit Facility, Maximum Borrowing Capacity	$ 516,000,000
Line of Credit Facility, Asset Restrictions	500,000,000
Credit Facility 1 [Member] | Secured by aircraft [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 250,000,000
Line of Credit Facility, Expiration Date	Jun. 30, 2021
Credit Facility 2 [Member] | Secured by aircraft [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity		$ 116,000,000	$ 75,000,000
Line of Credit Facility, Expiration Date	Jul. 31, 2019
Credit Facility 3 [Member] | Secured by certain accounts receivable, spare engines, spare parts and ground service equipment [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 150,000,000
Line of Credit Facility, Expiration Date	Mar. 31, 2022

EMPLOYEE BENEFIT PLANS - NET PE

EMPLOYEE BENEFIT PLANS - NET PENSION EXPENSE (Details) - Qualified Defined Benefit [Member] - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	$ 12	$ 10	$ 36	$ 30
Interest cost	20	19	59	55
Expected return on assets	(27)	(27)	(80)	(80)
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	(1)	(1)	(1)	(1)
Recognized actuarial loss (gain)	9	7	25	20
Wages and Benefits [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Net pension expense	12	10	36	30
Nonoperating Income (Expense) [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Net pension expense	$ 1	$ (2)	$ 3	$ (6)

COMMITMENTS (Details)

COMMITMENTS (Details) $ in Millions	1 Months Ended	3 Months Ended		9 Months Ended
	Jul. 31, 2018USD ($)	Sep. 30, 2018USD ($)aircraft	Sep. 30, 2017USD ($)	Sep. 30, 2018USD ($)aircraft	Sep. 30, 2017USD ($)
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Rent Expense		$ 165	$ 145	$ 455	$ 406
B-737 [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Committed to Purchase (in Aircraft) | aircraft		38		38
Options to Purchase Additional (in Aircraft) | aircraft		37		37
B737-900ER [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Committed to Purchase (in Aircraft) | aircraft		6		6
B737 MAX [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Committed to Purchase (in Aircraft) | aircraft		32		32
Unrecorded Unconditional Purchase Obligation, Minimum Quantity Required, Number Converted to MAX 9 | aircraft		15		15
A320neo [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Unrecorded Unconditional Purchase Obligation, Option to Cancel | aircraft		30		30
E175 [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Committed to Purchase (in Aircraft) | aircraft		17		17
Options to Purchase Additional (in Aircraft) | aircraft		30		30
Property Subject to Operating Lease [Member] | B-737 [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Number of units involved in lease contracts | aircraft		10		10
Property Subject to Operating Lease [Member] | Airbus [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Number of units involved in lease contracts | aircraft		61		61
Property Subject to Operating Lease [Member] | Q400 [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Number of units involved in lease contracts | aircraft		9		9
Property Subject to Operating Lease [Member] | E175 [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Number of units involved in lease contracts | aircraft		32		32
Property Available for Operating Lease [Member] | A321neo [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Number of optional additional units | aircraft		2		2
Property Available for Operating Lease [Member] | E175 [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Number of optional additional units | aircraft		3		3
Capacity Purchase Agreement with SkyWest [Member] | E175 [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Number of optional additional units | aircraft		8		8
Aircraft Maintenance Deposits [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Remainder of 2018		$ 16		$ 16
2,019		65		65
2,020		68		68
2,021		64		64
2,022		52		52
Thereafter		38		38
Total		303		303
Aircraft Commitments [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Remainder of 2018		378		378
2,019		514		514
2,020		525		525
2,021		558		558
2,022		302		302
Thereafter		140		140
Total		2,417		2,417
Capacity Purchase Agreements [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Remainder of 2018		33		33
2,019		138		138
2,020		145		145
2,021		166		166
2,022		174		174
Thereafter		1,205		1,205
Total		1,861		1,861
Aircraft Leases [Member]
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Remainder of 2018		88		88
2,019		349		349
2,020		324		324
2,021		282		282
2,022		265		265
Thereafter		1,070		1,070
Total		2,378		2,378
Facility Leases [Member]
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Remainder of 2018		18		18
2,019		64		64
2,020		56		56
2,021		50		50
2,022		35		35
Thereafter		149		149
Total		$ 372		$ 372
Virgin America Flight Attendants [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Loss Contingency, Damages Sought, Value	$ 85

SHAREHOLDERS' EQUITY, CASH DIVI

SHAREHOLDERS' EQUITY, CASH DIVIDEND (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Equity [Abstract]
Cash dividend declared per share (usd per share)	$ 0.32	$ 0.3	$ 0.96	$ 0.90
Payments of Dividends	$ 39		$ 118	$ 111

SHAREHOLDERS' EQUITY, COMMON ST

SHAREHOLDERS' EQUITY, COMMON STOCK REPURCHASE (Details) - 2015 1 Billion Repurchase Program [Member] - USD ($) $ in Millions	3 Months Ended		9 Months Ended		37 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Aug. 31, 2015
Class of Stock [Line Items]
Stock repurchase program, authorized amount						$ 1,000
Stock repurchased during period (shares)					5,676,305
Value of stock repurchased during period					$ 426
Shares	193,203	355,415	582,942	612,095
Amount	$ 12	$ 28	$ 37	$ 50

SHAREHOLDERS' EQUITY, ACCUMULAT

SHAREHOLDERS' EQUITY, ACCUMULATED OTHER COMPREHENSIVE LOSS (Details) - USD ($) $ in Millions	Jan. 01, 2018	Sep. 30, 2018	Dec. 31, 2017
Equity [Abstract]
Related to marketable securities		$ (17)	$ (5)
Related to employee benefit plans		(420)	(376)
Related to interest rate derivatives		9	1
Total		$ (428)	$ (380)
Reclassification from AOCI to retained earnings	$ 62

OPERATING SEGMENT INFORMATION_2

OPERATING SEGMENT INFORMATION (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018USD ($)	Sep. 30, 2017USD ($)	Sep. 30, 2018USD ($)segment	Sep. 30, 2017USD ($)
Segment Reporting Information [Line Items]
Number of Operating Segments | segment			3
Operating Revenues
Total Operating Revenues	$ 2,212	$ 2,110	$ 6,200	$ 5,952
Operating expenses
Operating Expenses, Excluding Fuel	1,402	1,315	4,206	3,830
Economic fuel	513	368	1,397	1,051
Total Operating Expenses	1,915	1,683	5,603	4,881
Nonoperating Income (Expense)
Interest income	11	9	29	25
Interest expense	(22)	(26)	(71)	(77)
Interest Costs Capitalized	5	5	14	13
Other	(7)	2	(20)	1
Nonoperating Income (Expense) Total	(13)	(10)	(48)	(38)
Income (loss) before income tax	284	417	549	1,033
Air Group Adjusted [Member]
Operating Revenues
Total Operating Revenues	2,212	2,110	6,200	5,952
Operating expenses
Operating Expenses, Excluding Fuel	1,380	1,292	4,114	3,744
Economic fuel	508	373	1,427	1,044
Total Operating Expenses	1,888	1,665	5,541	4,788
Nonoperating Income (Expense)
Interest income	11	9	29	25
Interest expense	(22)	(26)	(71)	(77)
Interest Costs Capitalized	5	5	14	13
Other	(7)	2	(20)	1
Nonoperating Income (Expense) Total	(13)	(10)	(48)	(38)
Income (loss) before income tax	311	435	611	1,126
Alaska Mainline [Member]
Operating Revenues
Total Operating Revenues	1,884	1,820	5,322	5,147
Operating expenses
Operating Expenses, Excluding Fuel	1,126	1,081	3,392	3,111
Economic fuel	438	328	1,237	924
Total Operating Expenses	1,564	1,409	4,629	4,035
Nonoperating Income (Expense)
Interest income	15	12	39	29
Interest expense	(20)	(25)	(64)	(72)
Interest Costs Capitalized	4	5	12	12
Other	(5)	2	(9)	1
Nonoperating Income (Expense) Total	(6)	(6)	(22)	(30)
Income (loss) before income tax	314	405	671	1,082
Alaska Regional [Member]
Operating Revenues
Total Operating Revenues	326	289	874	802
Operating expenses
Operating Expenses, Excluding Fuel	267	219	755	625
Economic fuel	70	45	190	120
Total Operating Expenses	337	264	945	745
Nonoperating Income (Expense)
Interest income	0	0	0	0
Interest expense	0	0	0	0
Interest Costs Capitalized	0	0	0	0
Other	(2)	0	(11)	0
Nonoperating Income (Expense) Total	(2)	0	(11)	0
Income (loss) before income tax	(13)	25	(82)	57
Horizon [Member]
Operating Revenues
Total Operating Revenues	130	113	379	320
Operating expenses
Operating Expenses, Excluding Fuel	118	104	345	323
Economic fuel	0	0	0	0
Total Operating Expenses	118	104	345	323
Nonoperating Income (Expense)
Interest income	0	0	0	0
Interest expense	(6)	(4)	(16)	(9)
Interest Costs Capitalized	1	0	2	1
Other	0	0	0	0
Nonoperating Income (Expense) Total	(5)	(4)	(14)	(8)
Income (loss) before income tax	7	5	20	(11)
Intersegment Elimination [Member]
Operating Revenues
Total Operating Revenues	(128)	(112)	(375)	(317)
Operating expenses
Operating Expenses, Excluding Fuel	(131)	(112)	(378)	(315)
Economic fuel	0	0	0	0
Total Operating Expenses	(131)	(112)	(378)	(315)
Nonoperating Income (Expense)
Interest income	(4)	(3)	(10)	(4)
Interest expense	4	3	9	4
Interest Costs Capitalized	0	0	0	0
Other	0	0	0	0
Nonoperating Income (Expense) Total	0	0	(1)	0
Income (loss) before income tax	3	0	2	(2)
Special Revenue and Charges [Member]
Operating Revenues
Total Operating Revenues	0	0	0	0
Operating expenses
Operating Expenses, Excluding Fuel	22	23	92	86
Economic fuel	5	(5)	(30)	7
Total Operating Expenses	27	18	62	93
Nonoperating Income (Expense)
Interest income	0	0	0	0
Interest expense	0	0	0	0
Interest Costs Capitalized	0	0	0	0
Other	0	0	0	0
Nonoperating Income (Expense) Total	0	0	0	0
Income (loss) before income tax	(27)	(18)	(62)	(93)
Passenger [Member]
Operating Revenues
Revenue from contract with customer, including assessed taxes	2,043	1,958	5,725	5,505
Passenger [Member] | Air Group Adjusted [Member]
Operating Revenues
Revenue from contract with customer, including assessed taxes	2,043	1,958	5,725	5,505
Passenger [Member] | Alaska Mainline [Member]
Operating Revenues
Revenue from contract with customer, including assessed taxes	1,727	1,677	4,880	4,729
Passenger [Member] | Alaska Regional [Member]
Operating Revenues
Revenue from contract with customer, including assessed taxes	316	281	845	776
Passenger [Member] | Horizon [Member]
Operating Revenues
Revenue from contract with customer, including assessed taxes	0	0	0	0
Passenger [Member] | Intersegment Elimination [Member]
Operating Revenues
Revenue from contract with customer, including assessed taxes	0	0	0	0
Passenger [Member] | Special Revenue and Charges [Member]
Operating Revenues
Revenue from contract with customer, including assessed taxes	0	0	0	0
Capacity Purchase Agreements [Member]
Operating Revenues
Revenue from contract with customer, including assessed taxes	0	0	0	0
Capacity Purchase Agreements [Member] | Air Group Adjusted [Member]
Operating Revenues
Revenue from contract with customer, including assessed taxes	0	0	0	0
Capacity Purchase Agreements [Member] | Alaska Mainline [Member]
Operating Revenues
Revenue from contract with customer, including assessed taxes	0	0	0	0
Capacity Purchase Agreements [Member] | Alaska Regional [Member]
Operating Revenues
Revenue from contract with customer, including assessed taxes	0	0	0	0
Capacity Purchase Agreements [Member] | Horizon [Member]
Operating Revenues
Revenue from contract with customer, including assessed taxes	128	112	375	317
Capacity Purchase Agreements [Member] | Intersegment Elimination [Member]
Operating Revenues
Revenue from contract with customer, including assessed taxes	(128)	(112)	(375)	(317)
Capacity Purchase Agreements [Member] | Special Revenue and Charges [Member]
Operating Revenues
Revenue from contract with customer, including assessed taxes	0	0	0	0
Mileage plan other revenue [Member]
Operating Revenues
Revenue from contract with customer, including assessed taxes	114	105	329	314
Mileage plan other revenue [Member] | Air Group Adjusted [Member]
Operating Revenues
Revenue from contract with customer, including assessed taxes	114	105	329	314
Mileage plan other revenue [Member] | Alaska Mainline [Member]
Operating Revenues
Revenue from contract with customer, including assessed taxes	104	97	301	291
Mileage plan other revenue [Member] | Alaska Regional [Member]
Operating Revenues
Revenue from contract with customer, including assessed taxes	10	8	28	23
Mileage plan other revenue [Member] | Horizon [Member]
Operating Revenues
Revenue from contract with customer, including assessed taxes	0	0	0	0
Mileage plan other revenue [Member] | Intersegment Elimination [Member]
Operating Revenues
Revenue from contract with customer, including assessed taxes	0	0	0	0
Mileage plan other revenue [Member] | Special Revenue and Charges [Member]
Operating Revenues
Revenue from contract with customer, including assessed taxes	0	0	0	0
Cargo and Freight [Member]
Operating Revenues
Revenue from contract with customer, including assessed taxes	55	47	146	133
Cargo and Freight [Member] | Air Group Adjusted [Member]
Operating Revenues
Revenue from contract with customer, including assessed taxes	55	47	146	133
Cargo and Freight [Member] | Alaska Mainline [Member]
Operating Revenues
Revenue from contract with customer, including assessed taxes	53	46	141	127
Cargo and Freight [Member] | Alaska Regional [Member]
Operating Revenues
Revenue from contract with customer, including assessed taxes	0	0	1	3
Cargo and Freight [Member] | Horizon [Member]
Operating Revenues
Revenue from contract with customer, including assessed taxes	2	1	4	3
Cargo and Freight [Member] | Intersegment Elimination [Member]
Operating Revenues
Revenue from contract with customer, including assessed taxes	0	0	0	0
Cargo and Freight [Member] | Special Revenue and Charges [Member]
Operating Revenues
Revenue from contract with customer, including assessed taxes	$ 0	$ 0	$ 0	$ 0

OPERATING SEGMENT INFORMATION,

OPERATING SEGMENT INFORMATION, ASSETS (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Total assets	$ 10,893	$ 10,746
Alaska Airlines [Member]
Total assets	14,725	16,663
Horizon [Member]
Total assets	1,037	929
Parent [Member]
Total assets	$ (4,869)	$ (6,846)