Alaska Air (ALK) 10-Q 8 Aug 18 2018 Q2 Quarterly report Financial data

DOCUMENT AND ENTITY INFORMATION

DOCUMENT AND ENTITY INFORMATION - shares	6 Months Ended
	Jun. 30, 2018	Jul. 31, 2018
Document and Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q2
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		123,144,939

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Current Assets
Cash and cash equivalents	$ 102	$ 194
Marketable securities	1,466	1,427
Total cash and marketable securities	1,568	1,621
Receivables—net	411	341
Inventories and supplies—net	57	57
Prepaid expenses and other current assets	180	133
Total Current Assets	2,216	2,152
Property and Equipment
Aircraft and other flight equipment	7,788	7,559
Other property and equipment	1,291	1,222
Deposits for future flight equipment	505	494
Property and Equipment Total	9,584	9,275
Less accumulated depreciation and amortization	3,091	2,991
Total Property and Equipment—Net	6,493	6,284
Goodwill	1,943	1,943
Intangible assets	130	133
Other noncurrent assets	273	234
Other Assets	2,346	2,310
Total Assets	11,055	10,746
Current Liabilities
Accounts payable	115	120
Accrued wages, vacation and payroll taxes	345	418
Air traffic liability	1,112	806
Other accrued liabilities	483	400
Deferred revenue, current	667	635
Current portion of long-term debt	314	307
Total Current Liabilities	3,036	2,686
Long-Term Debt, Net of Current Portion	1,998	2,262
Other Liabilities and Credits
Deferred income taxes	437	370
Deferred revenue, noncurrent	1,110	1,090
Obligation for pension and postretirement medical benefits	464	453
Other liabilities	417	425
Other Liabilities and Credits Totals	2,428	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 - 130,436,306 shares; 2017 - 129,903,498 shares, Outstanding: 2018 - 123,203,707 shares; 2017 - 123,060,638 shares	1	1
Capital in excess of par value	198	164
Treasury stock (common), at cost: 2018 - 7,232,599 shares; 2017 - 6,842,860 shares	(544)	(518)
Accumulated other comprehensive loss	(435)	(380)
Retained earnings	4,373	4,193
Total Shareholders' Equity	3,593	3,460
Total Liabilities and Shareholders' Equity	$ 11,055	$ 10,746

CONDENSED CONSOLIDATED BALANCE3

CONDENSED CONSOLIDATED BALANCE SHEETS (PARENTHETICALS) - $ / shares	Jun. 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)	130,436,306	129,903,498
Common stock, shares outstanding (shares)	123,203,707	123,060,638
Treasury Stock, Shares (shares)	7,232,599	6,842,860

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Operating Revenues
Total Operating Revenues	$ 2,156	$ 2,102	$ 3,988	$ 3,842
Operating Expenses
Wages and benefits	544	470	1,080	920
Variable incentive pay	38	27	77	58
Aircraft fuel, including hedging gains and losses	475	344	884	683
Aircraft maintenance	106	96	213	183
Aircraft rent	77	69	151	134
Landing fees and other rentals	110	99	236	214
Contracted services	76	77	157	158
Selling expenses	88	102	166	185
Depreciation and amortization	97	90	191	180
Food and beverage service	55	50	105	95
Third-party regional carrier expense	39	27	76	54
Other	141	140	282	271
Special items—merger-related costs	39	24	45	63
Special items—other	0	0	25	0
Total Operating Expenses	1,885	1,615	3,688	3,198
Operating Income	271	487	300	644
Nonoperating Income (Expense)
Interest income	10	9	18	16
Interest expense	(25)	(26)	(49)	(51)
Interest capitalized	4	4	9	8
Other—net	(1)	0	(13)	(1)
Nonoperating Income (Expense) Total	(12)	(13)	(35)	(28)
Income Before Income Tax	259	474	265	616
Income tax expense	66	181	68	230
Net Income	$ 193	$ 293	$ 197	$ 386
Basic Earnings Per Share (usd per share)	$ 1.57	$ 2.37	$ 1.60	$ 3.12
Diluted Earnings Per Share (usd per share)	$ 1.56	$ 2.36	$ 1.59	$ 3.10
Shares used for computation:
Basic shares (shares)	123,268	123,573	123,212	123,534
Diluted shares (shares)	124,036	124,332	123,953	124,374
Cash dividend declared per share (usd per share)	$ 0.32	$ 0.3	$ 0.64	$ 0.60
Passenger Revenue [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	$ 1,997	$ 1,945	$ 3,682	$ 3,547
Passenger Revenue [Member] | Passenger [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	1,997	1,945	3,682	3,547
Mileage Plan Revenue [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	275	252	521	480
Mileage Plan Revenue [Member] | Passenger [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	167	143	306	271
Mileage Plan Revenue [Member] | Mileage plan other revenue [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	108	109	215	209
Cargo and Other Revenue [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	51	48	91	86
Cargo and Other Revenue [Member] | Cargo and Freight [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	$ 51	$ 48	$ 91	$ 86

CONDENSED CONSOLIDATED STATEME5

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE OPERATIONS - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statement of Comprehensive Income [Abstract]
Net Income	$ 193	$ 293	$ 197	$ 386
Related to marketable securities:
Unrealized holding gain (loss) arising during the period	(4)	1	(17)	4
Reclassification of (gain) loss into Other—net nonoperating income (expense)	1	1	3	1
Income tax effect	0	(1)	3	(2)
Total	(3)	1	(11)	3
Related to employee benefit plans:
Reclassification of net pension expense into Wages and benefits	7	5	14	11
Income tax effect	(1)	(1)	(3)	(3)
Total	6	4	11	8
Related to interest rate derivative instruments:
Unrealized holding gain (loss) arising during the period	2	(3)	8	(2)
Reclassification of (gain) loss into Aircraft rent	0	2	1	2
Income tax effect	0	1	(2)	0
Total	2	0	7	0
Other Comprehensive Income	5	5	7	11
Comprehensive Income	$ 198	$ 298	$ 204	$ 397

CONDENSED CONSOLIDATED STATEME6

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Cash flows from operating activities:
Net Income	$ 197	$ 386
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	191	180
Stock-based compensation and other	17	25
Changes in certain assets and liabilities:
Changes in deferred tax provision	67	127
Increase in air traffic liability	306	384
Increase in deferred revenue	52	69
Other—net	(104)	(87)
Net cash provided by operating activities	726	1,084
Property and equipment additions:
Aircraft and aircraft purchase deposits	(271)	(404)
Other flight equipment	(56)	(45)
Other property and equipment	(96)	(63)
Total property and equipment additions, including capitalized interest	(423)	(512)
Purchases of marketable securities	(529)	(1,010)
Sales and maturities of marketable securities	474	541
Other investing activities	10	10
Net cash used in investing activities	(468)	(971)
Cash flows from financing activities:
Long-term debt payments	(258)	(159)
Common stock repurchases	(25)	(22)
Dividends paid	(79)	(74)
Other financing activities	15	12
Net cash used in financing activities	(347)	(243)
Net increase (decrease) in cash, cash equivalents, and restricted cash	(89)	(130)
Cash, cash equivalents, and restricted cash at beginning of year	197	328
Cash, cash equivalents, and restricted cash at end of the period	108	198
Cash paid during the period for:
Interest (net of amount capitalized)	39	42
Income taxes	$ 0	$ 14

CONDENSED CONSOLIDATED STATEME7

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Parenthetical) - USD ($) $ in Millions	Jun. 30, 2018	Jun. 30, 2017
Statement of Cash Flows [Abstract]
Cash and cash equivalents	$ 102	$ 198
Restricted cash included in Prepaid expenses and other current assets	6	0
Total cash, cash equivalents, and restricted cash at end of the period	$ 108	$ 198

GENERAL AND SUMMARY OF SIGNIFIC

GENERAL AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	6 Months Ended
	Jun. 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 June 30, 2018 and the results of operations for the three and six months ended June 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 six months ended June 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. 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 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. The Company will not early adopt the standard. 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	6 Months Ended
	Jun. 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 six months ended June 30, 2017 (in millions): Three Months Ended June 30, 2017 Six Months Ended June 30, 2017 Adjustments Adjustments As Reported Revenue Recognition Retirement Benefits As Adjusted As Reported Revenue Recognition Retirement Benefits As Adjusted Operating Revenues Passenger Revenue $ 1,807 $ 138 $ — $ 1,945 $ 3,291 $ 256 $ — $ 3,547 Mileage plan other revenue 128 (19 ) — 109 247 (38 ) — 209 Cargo and other revenue 167 (119 ) — 48 313 (227 ) — 86 Total Operating Revenue 2,102 — — 2,102 3,851 (9 ) — 3,842 Operating Expenses Wages and benefits 469 — 1 470 917 — 3 920 Selling expenses 97 5 — 102 178 7 — 185 Special items—merger-related costs 24 — — 24 64 (1 ) — 63 All other operating expenses 1,019 — — 1,019 2,030 — — 2,030 Total Operating Expenses 1,609 5 1 1,615 3,189 6 3 3,198 Operating Income 493 (5 ) (1 ) 487 662 (15 ) (3 ) 644 Nonoperating Income (Expense) Other—net (1 ) — 1 — (4 ) — 3 (1 ) All other nonoperating income (expense) (13 ) — — (13 ) (27 ) — — (27 ) (14 ) — 1 (13 ) (31 ) — 3 (28 ) Income (loss) before income tax 479 (5 ) — 474 631 (15 ) — 616 Income tax expense (benefit) 183 (2 ) — 181 236 (6 ) — 230 Net Income (Loss) $ 296 $ (3 ) $ — $ 293 $ 395 $ (9 ) $ — $ 386 Condensed consolidated statement of cash flows for the six months ended June 30, 2017 (in millions): Six Months Ended June 30, 2017 As Reported Adjustments - Revenue Recognition As Adjusted Cash flows from operating activities: Net income $ 395 $ (9 ) $ 386 Adjustments to reconcile net income to net cash provided by operating activities: Depreciation and amortization 180 — 180 Stock-based compensation and other 25 — 25 Changes in certain assets and liabilities: Changes in deferred tax provision 132 (5 ) 127 Increase in air traffic liability 406 (22 ) 384 Increase in deferred revenue 15 54 69 Other—net (69 ) (18 ) (87 ) Net cash provided by operating activities 1,084 — 1,084 Net cash used in investing activities (971 ) — (971 ) Net cash used in financing activities (243 ) — (243 ) Net increase (decrease) in cash and cash equivalents (130 ) — (130 ) Cash and cash equivalents at beginning of year 328 — 328 Cash and cash equivalents at end of the period $ 198 $ — $ 198

REVENUE FROM CONTRACTS WITH CUS

REVENUE FROM CONTRACTS WITH CUSTOMERS	6 Months Ended
	Jun. 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 co-branded 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 to 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 June 30, Six Months Ended June 30, 2018 2017 2018 2017 Passenger ticket revenue, including ticket breakage and net of taxes and fees $ 1,693 $ 1,668 $ 3,121 $ 3,026 Passenger ancillary revenue 137 134 255 250 Mileage Plan TM passenger revenue 167 143 306 271 Total passenger revenue $ 1,997 $ 1,945 $ 3,682 $ 3,547 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, if unused or not exchanged, the Company elected to apply this practical expedient. 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 16 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 loyalty 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 loyalty 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 six months ended June 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 June 30, Six Months Ended June 30, 2018 2017 2018 2017 Passenger revenue $ 167 $ 143 $ 306 $ 271 Mileage Plan TM other revenue 108 109 215 209 Total Mileage Plan™ revenue $ 275 $ 252 $ 521 $ 480 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 June 30, Six Months Ended June 30, 2018 2017 2018 2017 Cargo revenue $ 34 $ 32 $ 60 $ 56 Other revenue 17 16 31 30 Total Cargo and other revenue $ 51 $ 48 $ 91 $ 86 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 $79 million and $89 million from the prior year-end air traffic liability balance for the three months ended June 30, 2018 and 2017 , and $513 million and $520 million for the six months ended June 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 affinity card partner and from other partners as mileage credits are sold until the payments are collected. The Company had $103 million of such receivables as of June 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): Six Months Ended June 30, 2018 2017 Total Deferred Revenue balance at January 1 $ 1,725 $ 1,534 Travel miles and companion certificate redemption - Passenger revenue (306 ) (271 ) Miles redeemed on partner airlines - Other revenue (44 ) (44 ) Increase in liability for mileage credits issued 402 382 Total Deferred Revenue balance at June 30 $ 1,777 $ 1,601 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 $31 million and $24 million as of June 30, 2018 and December 31, 2017 . The Company recorded related expense on the condensed consolidated statement of operations of $58 million and $66 million for the three months ended June 30, 2018 and 2017 , and $109 million and $122 million for the six months ended June 30, 2018 and 2017 .

FAIR VALUE MEASUREMENTS

FAIR VALUE MEASUREMENTS	6 Months Ended
	Jun. 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 June 30, 2018 , total cost basis for all marketable securities was $1.5 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): June 30, 2018 Level 1 Level 2 Total Assets Marketable securities U.S. government and agency securities $ 376 $ — $ 376 Foreign government bonds — 28 28 Asset-backed securities — 231 231 Mortgage-backed securities — 78 78 Corporate notes and bonds — 743 743 Municipal securities — 10 10 Total Marketable securities 376 1,090 1,466 Derivative instruments Fuel hedge—call options — 58 58 Interest rate swap agreements — 14 14 Total Assets $ 376 $ 1,162 $ 1,538 Liabilities Derivative instruments Interest rate swap agreements — (4 ) (4 ) Total Liabilities $ — $ (4 ) $ (4 ) 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 June 30, 2018 . Maturities for marketable securities (in millions): June 30, 2018 Cost Basis Fair Value Due in one year or less $ 263 $ 262 Due after one year through five years 1,195 1,173 Due after five years through 10 years 31 31 Total $ 1,489 $ 1,466 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 June 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): June 30, 2018 December 31, 2017 Fixed-rate debt at cost $ 838 $ 956 Non-recurring purchase price accounting fair value adjustment 3 3 Total fixed-rate debt $ 841 $ 959 Estimated fair value $ 831 $ 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 impairment was recognized in the three and six months ended June 30, 2018 or June 30, 2017 .

LONG-TERM DEBT

LONG-TERM DEBT	6 Months Ended
	Jun. 30, 2018
Debt Disclosure [Abstract]
LONG-TERM DEBT	LONG-TERM DEBT Long-term debt obligations on the consolidated balance sheet (in millions): June 30, 2018 December 31, 2017 Fixed-rate notes payable due through 2028 $ 841 $ 959 Variable-rate notes payable due through 2028 1,485 1,625 Less debt issuance costs (14 ) (15 ) Total debt 2,312 2,569 Less current portion 314 307 Long-term debt, less current portion $ 1,998 $ 2,262 Weighted-average fixed-interest rate 4.1 % 4.2 % Weighted-average variable-interest rate 3.5 % 2.8 % During the six months ended June 30, 2018 the Company made debt payments of $258 million , including the prepayment of $43 million of debt. At June 30, 2018 long-term debt principal payments for the next five years and thereafter are as follows (in millions): Total Remainder of 2018 $ 142 2019 317 2020 435 2021 418 2022 243 Thereafter 768 Total $ 2,323 Bank Lines of Credit The Company had three credit facilities totaling $475 million as of June 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. A second credit facility for $75 million expires in September 2018 , with a mechanism for annual renewal, and is secured by aircraft. Subsequent to June 30, 2018 , we increased this credit facility from $75 million to $116 million and extended the maturity date to July 2019 . 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 $75 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 June 30, 2018 .

EMPLOYEE BENEFIT PLANS

EMPLOYEE BENEFIT PLANS	6 Months Ended
	Jun. 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 June 30, Six Months Ended June 30, 2018 2017 2018 2017 Service cost $ 12 $ 10 $ 24 $ 20 Pension expense included in Wages and benefits 12 10 24 20 Interest cost 19 18 39 36 Expected return on assets (26 ) (26 ) (53 ) (53 ) Recognized actuarial loss (gain) 8 6 16 13 Pension expense (benefit) included in Nonoperating Income (Expense) $ 1 $ (2 ) $ 2 $ (4 )

COMMITMENTS

COMMITMENTS	6 Months Ended
	Jun. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS	COMMITMENTS AND CONTINGENCIES Future minimum payments for commitments as of June 30, 2018 (in millions): Aircraft Leases Facility Leases Aircraft Commitments (a) Capacity Purchase Agreements (b) Aircraft Maintenance Deposits Remainder of 2018 $ 177 $ 38 $ 467 $ 67 $ 32 2019 349 68 558 138 65 2020 323 61 515 145 68 2021 282 52 562 166 64 2022 264 33 304 174 52 Thereafter 1,071 139 141 1,205 38 Total $ 2,466 $ 391 $ 2,547 $ 1,895 $ 319 (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 airlines, as well as aircraft leases operated by third-parties. At June 30, 2018 , the Company had lease contracts for 10 Boeing 737 (B737) aircraft, 61 Airbus aircraft, 11 Bombardier Q400 aircraft, and 29 Embraer 175 (E175) with SkyWest Airlines, Inc. (SkyWest). The Company has an additional two scheduled lease deliveries of A321neo aircraft through 2019 , as well as six scheduled lease deliveries of E175 aircraft through 2021 to be operated by SkyWest. 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 in 2020 . 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 $137 million and $123 million for the three months ended June 30, 2018 and 2017 , and $290 million and $261 million for the six months ended June 30, 2018 and 2017 . Aircraft Commitments Aircraft purchase commitments include non-cancelable contractual commitments for aircraft and engines. As of June 30, 2018 , the Company had commitments to purchase 41 B737 aircraft ( 9 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 18 E175 aircraft with deliveries in the remainder of 2018 through 2021 and has cancelable purchase commitments for 30 Airbus A320neo aircraft with deliveries from 2021 through 2023 . In addition, the Company has options to purchase 37 B737 aircraft and 30 E175 aircraft. 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. Plaintiffs received class certification in November 2016. Virgin America filed a motion for summary judgment seeking to dismiss all claims on various federal preemption grounds. In January 2017, the Court denied in part and granted in part Virgin America’s motion. In January 2018, Virgin America filed a motion to decertify the class and Plaintiffs filed a motion for summary judgment seeking the court to rule in their favor on all remaining claims. In July 2018, the Court denied in part and granted in part Virgin America's motion to decertify the class and granted in part and denied in part Plaintiffs' motion for summary judgment. A trial on the remaining claim is currently set for October 2018. The Company believes the claims in this case are without factual and legal merit and intends to defend the remaining claim in this lawsuit and will appeal the claims decided in the Plaintiffs' favor. Management is currently assessing the potential impact of the July 2018 decision by the Court, and has not yet determined the range of possible outcomes. While management believes the outcome of subsequent appeals will ultimately resolve in favor of the Company's position, damages assessed in the Plaintiffs' favor under the July 2018 ruling could be material. 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 arbitrators, judges and juries.

SHAREHOLDERS' EQUITY

SHAREHOLDERS' EQUITY	6 Months Ended
	Jun. 30, 2018
Equity [Abstract]
SHAREHOLDERS' EQUITY	SHAREHOLDERS' EQUITY Dividends During the three months ended June 30, 2018 , the Company declared and paid cash dividends of $0.32 per share, or $40 million . During the six months ended June 30, 2018 , the Company declared and paid cash dividends of $0.64 per share, or $79 million . Common Stock Repurchase In August 2015 , the Board of Directors authorized a $1 billion share repurchase program. As of June 30, 2018 , the Company has repurchased 5.5 million shares for $413 million under this program. Share repurchase activity (in millions, except share amounts): Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Shares Amount Shares Amount Shares Amount Shares Amount 2015 Repurchase Program—$1 billion 204,078 $ 13 256,680 $ 22 389,739 $ 25 256,680 $ 22 Accumulated Other Comprehensive Loss Components of accumulated other comprehensive loss, net of tax (in millions): June 30, 2018 December 31, 2017 Related to marketable securities $ (17 ) $ (5 ) Related to employee benefit plans (425 ) (376 ) Related to interest rate derivatives 7 1 Total $ (435 ) $ (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 six months ended June 30, 2018 and 2017 , anti-dilutive shares excluded from the calculation of EPS were not material.

OPERATING SEGMENT INFORMATION

OPERATING SEGMENT INFORMATION	6 Months Ended
	Jun. 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 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 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 June 30, 2018 Mainline Regional Horizon Consolidating & Other (a) Air Group Adjusted (b) Special Items (c) Consolidated Operating revenues Passenger revenues $ 1,711 $ 286 $ — $ — $ 1,997 $ — $ 1,997 CPA revenues — — 137 (137 ) — — — Mileage plan other revenue 99 9 — — 108 — 108 Cargo and other 49 1 1 — 51 — 51 Total operating revenues 1,859 296 138 (137 ) 2,156 — 2,156 Operating expenses Operating expenses, excluding fuel 1,135 249 123 (136 ) 1,371 39 1,410 Economic fuel 432 65 — — 497 (22 ) 475 Total operating expenses 1,567 314 123 (136 ) 1,868 17 1,885 Nonoperating income (expense) Interest income 13 — — (3 ) 10 — 10 Interest expense (22 ) — (5 ) 2 (25 ) — (25 ) Interest capitalized 4 — — — 4 — 4 Other—net 1 (2 ) — — (1 ) — (1 ) Total Nonoperating income (expense) (4 ) (2 ) (5 ) (1 ) (12 ) — (12 ) Income (loss) before income tax $ 288 $ (20 ) $ 10 $ (2 ) $ 276 $ (17 ) $ 259 Three Months Ended June 30, 2017 (d) Mainline Regional Horizon Consolidating & Other (a) Air Group Adjusted (b) Special Items (c) Consolidated Operating revenues Passenger revenues $ 1,677 $ 268 $ — $ — $ 1,945 $ — $ 1,945 CPA revenues — — 108 (108 ) — — — Mileage plan other revenue 101 8 — — 109 — 109 Cargo and other 45 2 1 — 48 — 48 Total operating revenues 1,823 278 109 (108 ) 2,102 — 2,102 Operating expenses Operating expenses, excluding fuel 1,030 206 116 (105 ) 1,247 24 1,271 Economic fuel 304 38 — — 342 2 344 Total operating expenses 1,334 244 116 (105 ) 1,589 26 1,615 Nonoperating income (expense) Interest income 10 — — (1 ) 9 — 9 Interest expense (24 ) — (3 ) 1 (26 ) — (26 ) Interest capitalized 3 — 1 — 4 — 4 Other—net — — — — — — — Total Nonoperating income (expense) (11 ) — (2 ) — (13 ) — (13 ) Income (loss) before income tax $ 478 $ 34 $ (9 ) $ (3 ) $ 500 $ (26 ) $ 474 Six Months Ended June 30, 2018 (in millions) Mainline Regional Horizon Consolidating & Other (a) Air Group Adjusted (b) Special Items (c) Consolidated Operating revenues Passenger revenues $ 3,153 $ 529 $ — $ — $ 3,682 $ — $ 3,682 CPA revenues — — 247 (247 ) — — — Mileage plan other revenue 197 18 — — 215 — 215 Cargo and other 88 1 2 — 91 — 91 Total operating revenues 3,438 548 249 (247 ) 3,988 — 3,988 Operating expenses Operating expenses, excluding fuel 2,266 488 227 (247 ) 2,734 70 2,804 Economic fuel 799 120 — — 919 (35 ) 884 Total operating expenses 3,065 608 227 (247 ) 3,653 35 3,688 Nonoperating income (expense) Interest income 24 — — (6 ) 18 — 18 Interest expense (44 ) — (10 ) 5 (49 ) — (49 ) Interest capitalized 8 — 1 — 9 — 9 Other (4 ) (9 ) — — (13 ) — (13 ) Total Nonoperating income (expense) (16 ) (9 ) (9 ) (1 ) (35 ) — (35 ) Income (loss) before income tax $ 357 $ (69 ) $ 13 $ (1 ) $ 300 $ (35 ) $ 265 Six Months Ended June 30, 2017 (d) (in millions) Mainline Regional Horizon Consolidating & Other (a) Air Group Adjusted (b) Special Items (c) Consolidated Operating revenues Passenger revenues $ 3,052 $ 495 $ — $ — $ 3,547 $ — $ 3,547 CPA revenues — — 205 (205 ) — — — Mileage plan other revenue 194 15 — — 209 — 209 Cargo and other 81 3 2 — 86 — 86 Total operating revenues 3,327 513 207 (205 ) 3,842 — 3,842 Operating expenses Operating expenses, excluding fuel 2,030 406 219 (203 ) 2,452 63 2,515 Economic fuel 596 75 — — 671 12 683 Total operating expenses 2,626 481 219 (203 ) 3,123 75 3,198 Nonoperating income (expense) Interest income 17 — — (1 ) 16 — 16 Interest expense (47 ) — (5 ) 1 (51 ) — (51 ) Interest capitalized 7 — 1 — 8 — 8 Other (1 ) — — — (1 ) — (1 ) Total Nonoperating income (expense) (24 ) — (4 ) — (28 ) — (28 ) Income (loss) before income tax $ 677 $ 32 $ (16 ) $ (2 ) $ 691 $ (75 ) $ 616 (a) Includes consolidating entries, 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): June 30, 2018 December 31, 2017 Mainline $ 15,334 $ 16,663 Horizon 1,039 929 Consolidating & Other (5,318 ) (6,846 ) Consolidated $ 11,055 $ 10,746

GENERAL AND SUMMARY OF SIGNIF17

GENERAL AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	6 Months Ended
	Jun. 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 June 30, 2018 and the results of operations for the three and six months ended June 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 six months ended June 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. 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 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. The Company will not early adopt the standard. 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 P18

RECENTLY ADOPTED ACCOUNTING PRONOUNCEMENTS (Tables)	6 Months Ended
	Jun. 30, 2018
Accounting Changes and Error Corrections [Abstract]
Schedule of New Accounting Pronouncements Impact	Condensed consolidated statement of operations for the three and six months ended June 30, 2017 (in millions): Three Months Ended June 30, 2017 Six Months Ended June 30, 2017 Adjustments Adjustments As Reported Revenue Recognition Retirement Benefits As Adjusted As Reported Revenue Recognition Retirement Benefits As Adjusted Operating Revenues Passenger Revenue $ 1,807 $ 138 $ — $ 1,945 $ 3,291 $ 256 $ — $ 3,547 Mileage plan other revenue 128 (19 ) — 109 247 (38 ) — 209 Cargo and other revenue 167 (119 ) — 48 313 (227 ) — 86 Total Operating Revenue 2,102 — — 2,102 3,851 (9 ) — 3,842 Operating Expenses Wages and benefits 469 — 1 470 917 — 3 920 Selling expenses 97 5 — 102 178 7 — 185 Special items—merger-related costs 24 — — 24 64 (1 ) — 63 All other operating expenses 1,019 — — 1,019 2,030 — — 2,030 Total Operating Expenses 1,609 5 1 1,615 3,189 6 3 3,198 Operating Income 493 (5 ) (1 ) 487 662 (15 ) (3 ) 644 Nonoperating Income (Expense) Other—net (1 ) — 1 — (4 ) — 3 (1 ) All other nonoperating income (expense) (13 ) — — (13 ) (27 ) — — (27 ) (14 ) — 1 (13 ) (31 ) — 3 (28 ) Income (loss) before income tax 479 (5 ) — 474 631 (15 ) — 616 Income tax expense (benefit) 183 (2 ) — 181 236 (6 ) — 230 Net Income (Loss) $ 296 $ (3 ) $ — $ 293 $ 395 $ (9 ) $ — $ 386 Condensed consolidated statement of cash flows for the six months ended June 30, 2017 (in millions): Six Months Ended June 30, 2017 As Reported Adjustments - Revenue Recognition As Adjusted Cash flows from operating activities: Net income $ 395 $ (9 ) $ 386 Adjustments to reconcile net income to net cash provided by operating activities: Depreciation and amortization 180 — 180 Stock-based compensation and other 25 — 25 Changes in certain assets and liabilities: Changes in deferred tax provision 132 (5 ) 127 Increase in air traffic liability 406 (22 ) 384 Increase in deferred revenue 15 54 69 Other—net (69 ) (18 ) (87 ) Net cash provided by operating activities 1,084 — 1,084 Net cash used in investing activities (971 ) — (971 ) Net cash used in financing activities (243 ) — (243 ) Net increase (decrease) in cash and cash equivalents (130 ) — (130 ) Cash and cash equivalents at beginning of year 328 — 328 Cash and cash equivalents at end of the period $ 198 $ — $ 198

REVENUE FROM CONTRACTS WITH C19

REVENUE FROM CONTRACTS WITH CUSTOMERS (Tables)	6 Months Ended
	Jun. 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 June 30, Six Months Ended June 30, 2018 2017 2018 2017 Cargo revenue $ 34 $ 32 $ 60 $ 56 Other revenue 17 16 31 30 Total Cargo and other revenue $ 51 $ 48 $ 91 $ 86 Mileage Plan™ revenue included in the condensed consolidated statements of operations (in millions): Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Passenger revenue $ 167 $ 143 $ 306 $ 271 Mileage Plan TM other revenue 108 109 215 209 Total Mileage Plan™ revenue $ 275 $ 252 $ 521 $ 480 Passenger revenue recognized in the condensed consolidated statements of operations (in millions): Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Passenger ticket revenue, including ticket breakage and net of taxes and fees $ 1,693 $ 1,668 $ 3,121 $ 3,026 Passenger ancillary revenue 137 134 255 250 Mileage Plan TM passenger revenue 167 143 306 271 Total passenger revenue $ 1,997 $ 1,945 $ 3,682 $ 3,547
Contract with Customer Liabilities	The table below presents a roll forward of the total frequent flyer liability (in millions): Six Months Ended June 30, 2018 2017 Total Deferred Revenue balance at January 1 $ 1,725 $ 1,534 Travel miles and companion certificate redemption - Passenger revenue (306 ) (271 ) Miles redeemed on partner airlines - Other revenue (44 ) (44 ) Increase in liability for mileage credits issued 402 382 Total Deferred Revenue balance at June 30 $ 1,777 $ 1,601

FAIR VALUE MEASUREMENTS (Tables

FAIR VALUE MEASUREMENTS (Tables)	6 Months Ended
	Jun. 30, 2018
Fair Value Disclosures [Abstract]
Activity for Marketable Securities
Investments Classified by Contractual Maturity Date	Maturities for marketable securities (in millions): June 30, 2018 Cost Basis Fair Value Due in one year or less $ 263 $ 262 Due after one year through five years 1,195 1,173 Due after five years through 10 years 31 31 Total $ 1,489 $ 1,466
Fair Value, by Balance Sheet Grouping	Fixed-rate debt on the consolidated balance sheet and the estimated fair value of long-term fixed-rate debt is as follows (in millions): June 30, 2018 December 31, 2017 Fixed-rate debt at cost $ 838 $ 956 Non-recurring purchase price accounting fair value adjustment 3 3 Total fixed-rate debt $ 841 $ 959 Estimated fair value $ 831 $ 959 Fair values of financial instruments on the consolidated balance sheet (in millions): June 30, 2018 Level 1 Level 2 Total Assets Marketable securities U.S. government and agency securities $ 376 $ — $ 376 Foreign government bonds — 28 28 Asset-backed securities — 231 231 Mortgage-backed securities — 78 78 Corporate notes and bonds — 743 743 Municipal securities — 10 10 Total Marketable securities 376 1,090 1,466 Derivative instruments Fuel hedge—call options — 58 58 Interest rate swap agreements — 14 14 Total Assets $ 376 $ 1,162 $ 1,538 Liabilities Derivative instruments Interest rate swap agreements — (4 ) (4 ) Total Liabilities $ — $ (4 ) $ (4 ) 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 )

LONG-TERM DEBT (Tables)

LONG-TERM DEBT (Tables)	6 Months Ended
	Jun. 30, 2018
Debt Disclosure [Abstract]
Schedule of Long-term Debt Instruments	Long-term debt obligations on the consolidated balance sheet (in millions): June 30, 2018 December 31, 2017 Fixed-rate notes payable due through 2028 $ 841 $ 959 Variable-rate notes payable due through 2028 1,485 1,625 Less debt issuance costs (14 ) (15 ) Total debt 2,312 2,569 Less current portion 314 307 Long-term debt, less current portion $ 1,998 $ 2,262 Weighted-average fixed-interest rate 4.1 % 4.2 % Weighted-average variable-interest rate 3.5 % 2.8 %
Schedule of Maturities of Long-term Debt	At June 30, 2018 long-term debt principal payments for the next five years and thereafter are as follows (in millions): Total Remainder of 2018 $ 142 2019 317 2020 435 2021 418 2022 243 Thereafter 768 Total $ 2,323

EMPLOYEE BENEFIT PLANS (Tables)

EMPLOYEE BENEFIT PLANS (Tables)	6 Months Ended
	Jun. 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 June 30, Six Months Ended June 30, 2018 2017 2018 2017 Service cost $ 12 $ 10 $ 24 $ 20 Pension expense included in Wages and benefits 12 10 24 20 Interest cost 19 18 39 36 Expected return on assets (26 ) (26 ) (53 ) (53 ) Recognized actuarial loss (gain) 8 6 16 13 Pension expense (benefit) included in Nonoperating Income (Expense) $ 1 $ (2 ) $ 2 $ (4 )

COMMITMENTS (Tables)

COMMITMENTS (Tables)	6 Months Ended
	Jun. 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 June 30, 2018 (in millions): Aircraft Leases Facility Leases Aircraft Commitments (a) Capacity Purchase Agreements (b) Aircraft Maintenance Deposits Remainder of 2018 $ 177 $ 38 $ 467 $ 67 $ 32 2019 349 68 558 138 65 2020 323 61 515 145 68 2021 282 52 562 166 64 2022 264 33 304 174 52 Thereafter 1,071 139 141 1,205 38 Total $ 2,466 $ 391 $ 2,547 $ 1,895 $ 319 (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)	6 Months Ended
	Jun. 30, 2018
Equity [Abstract]
Schedule of Treasury Stock by Class	Share repurchase activity (in millions, except share amounts): Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Shares Amount Shares Amount Shares Amount Shares Amount 2015 Repurchase Program—$1 billion 204,078 $ 13 256,680 $ 22 389,739 $ 25 256,680 $ 22
Schedule of Accumulated Other Comprehensive Income (Loss)	Components of accumulated other comprehensive loss, net of tax (in millions): June 30, 2018 December 31, 2017 Related to marketable securities $ (17 ) $ (5 ) Related to employee benefit plans (425 ) (376 ) Related to interest rate derivatives 7 1 Total $ (435 ) $ (380 )

OPERATING SEGMENT INFORMATION (

OPERATING SEGMENT INFORMATION (Tables)	6 Months Ended
	Jun. 30, 2018
Segment Reporting [Abstract]
Schedule of Segment Reporting Information, by Segment	Operating segment information is as follows (in millions): Three Months Ended June 30, 2018 Mainline Regional Horizon Consolidating & Other (a) Air Group Adjusted (b) Special Items (c) Consolidated Operating revenues Passenger revenues $ 1,711 $ 286 $ — $ — $ 1,997 $ — $ 1,997 CPA revenues — — 137 (137 ) — — — Mileage plan other revenue 99 9 — — 108 — 108 Cargo and other 49 1 1 — 51 — 51 Total operating revenues 1,859 296 138 (137 ) 2,156 — 2,156 Operating expenses Operating expenses, excluding fuel 1,135 249 123 (136 ) 1,371 39 1,410 Economic fuel 432 65 — — 497 (22 ) 475 Total operating expenses 1,567 314 123 (136 ) 1,868 17 1,885 Nonoperating income (expense) Interest income 13 — — (3 ) 10 — 10 Interest expense (22 ) — (5 ) 2 (25 ) — (25 ) Interest capitalized 4 — — — 4 — 4 Other—net 1 (2 ) — — (1 ) — (1 ) Total Nonoperating income (expense) (4 ) (2 ) (5 ) (1 ) (12 ) — (12 ) Income (loss) before income tax $ 288 $ (20 ) $ 10 $ (2 ) $ 276 $ (17 ) $ 259 Three Months Ended June 30, 2017 (d) Mainline Regional Horizon Consolidating & Other (a) Air Group Adjusted (b) Special Items (c) Consolidated Operating revenues Passenger revenues $ 1,677 $ 268 $ — $ — $ 1,945 $ — $ 1,945 CPA revenues — — 108 (108 ) — — — Mileage plan other revenue 101 8 — — 109 — 109 Cargo and other 45 2 1 — 48 — 48 Total operating revenues 1,823 278 109 (108 ) 2,102 — 2,102 Operating expenses Operating expenses, excluding fuel 1,030 206 116 (105 ) 1,247 24 1,271 Economic fuel 304 38 — — 342 2 344 Total operating expenses 1,334 244 116 (105 ) 1,589 26 1,615 Nonoperating income (expense) Interest income 10 — — (1 ) 9 — 9 Interest expense (24 ) — (3 ) 1 (26 ) — (26 ) Interest capitalized 3 — 1 — 4 — 4 Other—net — — — — — — — Total Nonoperating income (expense) (11 ) — (2 ) — (13 ) — (13 ) Income (loss) before income tax $ 478 $ 34 $ (9 ) $ (3 ) $ 500 $ (26 ) $ 474 Six Months Ended June 30, 2018 (in millions) Mainline Regional Horizon Consolidating & Other (a) Air Group Adjusted (b) Special Items (c) Consolidated Operating revenues Passenger revenues $ 3,153 $ 529 $ — $ — $ 3,682 $ — $ 3,682 CPA revenues — — 247 (247 ) — — — Mileage plan other revenue 197 18 — — 215 — 215 Cargo and other 88 1 2 — 91 — 91 Total operating revenues 3,438 548 249 (247 ) 3,988 — 3,988 Operating expenses Operating expenses, excluding fuel 2,266 488 227 (247 ) 2,734 70 2,804 Economic fuel 799 120 — — 919 (35 ) 884 Total operating expenses 3,065 608 227 (247 ) 3,653 35 3,688 Nonoperating income (expense) Interest income 24 — — (6 ) 18 — 18 Interest expense (44 ) — (10 ) 5 (49 ) — (49 ) Interest capitalized 8 — 1 — 9 — 9 Other (4 ) (9 ) — — (13 ) — (13 ) Total Nonoperating income (expense) (16 ) (9 ) (9 ) (1 ) (35 ) — (35 ) Income (loss) before income tax $ 357 $ (69 ) $ 13 $ (1 ) $ 300 $ (35 ) $ 265 Six Months Ended June 30, 2017 (d) (in millions) Mainline Regional Horizon Consolidating & Other (a) Air Group Adjusted (b) Special Items (c) Consolidated Operating revenues Passenger revenues $ 3,052 $ 495 $ — $ — $ 3,547 $ — $ 3,547 CPA revenues — — 205 (205 ) — — — Mileage plan other revenue 194 15 — — 209 — 209 Cargo and other 81 3 2 — 86 — 86 Total operating revenues 3,327 513 207 (205 ) 3,842 — 3,842 Operating expenses Operating expenses, excluding fuel 2,030 406 219 (203 ) 2,452 63 2,515 Economic fuel 596 75 — — 671 12 683 Total operating expenses 2,626 481 219 (203 ) 3,123 75 3,198 Nonoperating income (expense) Interest income 17 — — (1 ) 16 — 16 Interest expense (47 ) — (5 ) 1 (51 ) — (51 ) Interest capitalized 7 — 1 — 8 — 8 Other (1 ) — — — (1 ) — (1 ) Total Nonoperating income (expense) (24 ) — (4 ) — (28 ) — (28 ) Income (loss) before income tax $ 677 $ 32 $ (16 ) $ (2 ) $ 691 $ (75 ) $ 616 (a) Includes consolidating entries, 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): June 30, 2018 December 31, 2017 Mainline $ 15,334 $ 16,663 Horizon 1,039 929 Consolidating & Other (5,318 ) (6,846 ) Consolidated $ 11,055 $ 10,746

GENERAL AND SUMMARY OF SIGNIF26

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 P27

RECENTLY ADOPTED ACCOUNTING PRONOUNCEMENTS (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2017	Jan. 01, 2016
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cash and cash equivalents					$ 102	$ 194	$ 198
Cash, cash equivalents, and restricted cash	$ 108	$ 198	$ 197	$ 328	108	197	198
Current Assets
Prepaid expenses and other current assets					180	133
Current Liabilities
Air traffic liability					1,112	806
Other accrued liabilities					483	400
Deferred revenue, current					667	635
Other Liabilities and Credits
Deferred income taxes					437	370
Deferred revenue, noncurrent					1,110	1,090
Other liabilities					417	425
Shareholders' Equity
Retained earnings					$ 4,373	$ 4,193
Operating Revenues
Total Operating Revenues	2,156	2,102	3,988	3,842
Operating Expenses
Wages and benefits	544	470	1,080	920
Selling expenses	88	102	166	185
Special items—merger-related costs	39	24	45	63
All other operating expenses		1,019		2,030
Total Operating Expenses	1,885	1,615	3,688	3,198
Operating Income	271	487	300	644
Nonoperating Income (Expense)
Other—net	(1)	0	(13)	(1)
Nonoperating Income (Expense), Other		(13)		(27)
Nonoperating Income (Expense) Total	(12)	(13)	(35)	(28)
Income Before Income Tax	259	474	265	616
Income tax expense	66	181	68	230
Net Income (loss)	193	293	197	386
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	97	90	191	180
Stock-based compensation and other			17	25
Changes in deferred tax provision			67	127
Increase in air traffic liability			306	384
Increase in deferred revenue			52	69
Other—net			(104)	(87)
Net cash provided by operating activities			726	1,084
Net cash used in investing activities			(468)	(971)
Net cash used in financing activities			(347)	(243)
Net increase (decrease) in cash, cash equivalents, and restricted cash			(89)	(130)
Cash, cash equivalents, and restricted cash at beginning of year			197	328
Cash, cash equivalents, and restricted cash at end of the period	108	198	108	198
As Reported [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cash, cash equivalents, and restricted cash		198		328			198
Operating Revenues
Mileage plan other revenue		128		247
Total Operating Revenues		2,102		3,851
Operating Expenses
Wages and benefits		469		917
Selling expenses		97		178
Special items—merger-related costs		24		64
All other operating expenses		1,019		2,030
Total Operating Expenses		1,609		3,189
Operating Income		493		662
Nonoperating Income (Expense)
Other—net		(1)		(4)
Nonoperating Income (Expense), Other		(13)		(27)
Nonoperating Income (Expense) Total		(14)		(31)
Income Before Income Tax		479		631
Income tax expense		183		236
Net Income (loss)		296		395
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization				180
Stock-based compensation and other				25
Changes in deferred tax provision				132
Increase in air traffic liability				406
Increase in deferred revenue				15
Other—net				(69)
Net cash provided by operating activities				1,084
Net cash used in investing activities				(971)
Net cash used in financing activities				(243)
Net increase (decrease) in cash, cash equivalents, and restricted cash				(130)
Cash, cash equivalents, and restricted cash at beginning of year				328
Cash, cash equivalents, and restricted cash at end of the period		198		198
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		(19)		(38)
Total Operating Revenues		0		(9)
Operating Expenses
Wages and benefits		0		0
Selling expenses		5		7
Special items—merger-related costs		0		(1)
All other operating expenses		0		0
Total Operating Expenses		5		6
Operating Income		(5)		(15)
Nonoperating Income (Expense)
Other—net		0		0
Nonoperating Income (Expense), Other		0		0
Nonoperating Income (Expense) Total		0		0
Income Before Income Tax		(5)		(15)
Income tax expense		(2)		(6)
Net Income (loss)		(3)		(9)
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				(5)
Increase in air traffic liability				(22)
Increase in deferred revenue				54
Other—net				(18)
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		1		3
Selling expenses		0		0
Special items—merger-related costs		0		0
All other operating expenses		0		0
Total Operating Expenses		1		3
Operating Income		(1)		(3)
Nonoperating Income (Expense)
Other—net		1		3
Nonoperating Income (Expense), Other		0		0
Nonoperating Income (Expense) Total		1		3
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	51	48	91	86
Cargo and Freight [Member] | As Reported [Member]
Operating Revenues
Revenue from contract with customer, including assessed taxes		167		313
Cargo and Freight [Member] | Accounting Standards Update 2014-09 [Member] | Adjustments [Member]
Operating Revenues
Revenue from contract with customer, including assessed taxes		(119)		(227)
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	1,997	1,945	3,682	3,547
Passenger [Member] | As Reported [Member]
Operating Revenues
Revenue from contract with customer, including assessed taxes		1,807		3,291
Passenger [Member] | Accounting Standards Update 2014-09 [Member] | Adjustments [Member]
Operating Revenues
Revenue from contract with customer, including assessed taxes		138		256
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	51	48	91	86
Cargo and Other Revenue [Member] | Cargo and Freight [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	$ 51	$ 48	$ 91	$ 86

REVENUE FROM CONTRACTS WITH C28

REVENUE FROM CONTRACTS WITH CUSTOMERS - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Passenger Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 1,997	$ 1,945	$ 3,682	$ 3,547
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	1,693	1,668	3,121	3,026
Passenger Revenue [Member] | Passenger ancillary revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	137	134	255	250
Passenger Revenue [Member] | Mileage Plan passenger revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	167	143	306	271
Passenger Revenue [Member] | Passenger [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	1,997	1,945	3,682	3,547
Mileage Plan Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	275	252	521	480
Mileage Plan Revenue [Member] | Passenger [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	167	143	306	271
Mileage Plan Revenue [Member] | Mileage plan other revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	108	109	215	209
Cargo and Other Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	51	48	91	86
Cargo and Other Revenue [Member] | Cargo revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	34	32	60	56
Cargo and Other Revenue [Member] | Other revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 17	$ 16	$ 31	$ 30

REVENUE FROM CONTRACTS WITH C29

REVENUE FROM CONTRACTS WITH CUSTOMERS - Narrative (Details) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018USD ($)	Jun. 30, 2017USD ($)	Jun. 30, 2018USD ($)airline	Jun. 30, 2017USD ($)	Dec. 31, 2017USD ($)
Deferred Revenue Arrangement [Line Items]
Number of airline partners | airline			16
Breakage rate	17.40%	17.40%	17.40%	17.40%
Air traffic liability	$ 1,112		$ 1,112		$ 806
Receivable	411		411		341
Contract cost recognized	58	$ 66	109	$ 122
Prepaid Expenses and Other Current Assets [Member]
Deferred Revenue Arrangement [Line Items]
Contract costs	31		31		24
Mileage Plan Revenue [Member]
Deferred Revenue Arrangement [Line Items]
Receivable	103		103		$ 101
Mileage Plan Revenue [Member] | Mileage plan other revenue [Member]
Deferred Revenue Arrangement [Line Items]
Contract liability revenue recognized			(44)	(44)
Passenger Revenue [Member]
Deferred Revenue Arrangement [Line Items]
Contract liability revenue recognized	$ 79	$ 89	$ 513	$ 520

REVENUE FROM CONTRACTS WITH C30

REVENUE FROM CONTRACTS WITH CUSTOMERS - Contract Liabilities Activity (Details) - Mileage Plan Revenue [Member] - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2018	Jun. 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	402	382
Total Deferred Revenue balance at June 30	1,777	1,601
Passenger revenue [Member]
Change in Contract with Customer, Liability [Roll Forward]
Revenue recognized	(306)	(271)
Mileage plan other revenue [Member]
Change in Contract with Customer, Liability [Roll Forward]
Revenue recognized	$ (44)	$ (44)

FAIR VALUE MEASUREMENTS - FAIR

FAIR VALUE MEASUREMENTS - FAIR VALUE OF ASSETS AND LIABILITIES (Details) - Recurring [Member] - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	$ 1,466	$ 1,427
Assets, Fair Value Disclosure	1,538	1,458
Financial and Nonfinancial Liabilities, Fair Value Disclosure	4	8
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	376	328
Assets, Fair Value Disclosure	376	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	1,090	1,099
Assets, Fair Value Disclosure	1,162	1,130
Financial and Nonfinancial Liabilities, Fair Value Disclosure	4	8
Fuel hedge contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative instruments, assets	58	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	58	22
Interest rate swaps agreements [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative instruments, assets	14	9
Derivative instruments, liabilities	4	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	14	9
Derivative instruments, liabilities	4	8
U.S. government and agency securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	376	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	376	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	28	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	28	43
Asset-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	231	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	231	209
Mortgage-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	78	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	78	99
Corporate notes and bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	743	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	743	726
Municipal securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	10	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	$ 10	$ 22

FAIR VALUE MEASUREMENTS - MATU

FAIR VALUE MEASUREMENTS - MATURITIES FOR MARKETABLE SECURITIES (Details) $ in Millions	Jun. 30, 2018USD ($)
Cost Basis
Due in one year or less	$ 263
Due after one year through five years	1,195
Due after five years through 10 years	31
Total	1,489
Fair Value
Due in one year or less	262
Due after one year through five years	1,173
Due after five years through 10 years	31
Total	$ 1,466

FAIR VALUE MEASUREMENTS - LONG-

FAIR VALUE MEASUREMENTS - LONG-TERM DEBT (Details) - USD ($) $ in Millions	Jun. 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	838	956
Long-term debt	841	959
Fair value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	$ 831	$ 959

LONG-TERM DEBT - SCHEDULE OF LO

LONG-TERM DEBT - SCHEDULE OF LONG-TERM DEBT (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Debt Instrument [Line Items]
Debt Issuance Costs, Net	$ (14)	$ (14)		$ (15)
Total	2,312	2,312		2,569
Less current portion	314	314		307
Long-term debt, less current portion	$ 1,998	$ 1,998		$ 2,262
Weighted-average fixed-interest rate	4.10%	4.10%		4.20%
Weighted-average variable-interest rate	3.50%	3.50%		2.80%
Long-term debt payments		$ 258	$ 159
Repayments of Debt	$ 43
Fixed rate notes payable due through 2028 [Member]
Debt Instrument [Line Items]
Total	841	841		$ 959
Variable rate notes payable due through 2028 [Member]
Debt Instrument [Line Items]
Total	$ 1,485	$ 1,485		$ 1,625

LONG-TERM DEBT LONG-TERM DEBT -

LONG-TERM DEBT LONG-TERM DEBT - FUTURE PAYMENTS (Details) $ in Millions	Jun. 30, 2018USD ($)
Long-term Debt, Fiscal Year Maturity [Abstract]
Remainder of 2018	$ 142
2,019	317
2,020	435
2,021	418
2,022	243
Thereafter	768
Total	$ 2,323

LONG-TERM DEBT - LINE OF CREDIT

LONG-TERM DEBT - LINE OF CREDIT (Details)	3 Months Ended	6 Months Ended
	Sep. 30, 2018	Jun. 30, 2018USD ($)credit_facility	Jul. 01, 2018USD ($)
Line of Credit Facility [Line Items]
Line of Credit Facility, Number of Credit Facilities | credit_facility		3
Line of Credit Facility, Maximum Borrowing Capacity		$ 475,000,000
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		$ 75,000,000
Line of Credit Facility, Expiration Date		Sep. 30, 2018
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
Subsequent Event [Member] | Credit Facility 2 [Member] | Secured by aircraft [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity			$ 116,000,000
Line of Credit Facility, Expiration Date	Jul. 31, 2019

EMPLOYEE BENEFIT PLANS - NET PE

EMPLOYEE BENEFIT PLANS - NET PENSION EXPENSE (Details) - Qualified Defined Benefit [Member] - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	$ 12	$ 10	$ 24	$ 20
Interest cost	19	18	39	36
Expected return on assets	(26)	(26)	(53)	(53)
Recognized actuarial loss (gain)	8	6	16	13
Wages and Benefits [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Net pension expense	12	10	24	20
Nonoperating Income (Expense) [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Net pension expense	$ 1	$ (2)	$ 2	$ (4)

COMMITMENTS (Details)

COMMITMENTS (Details) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018USD ($)aircraft	Jun. 30, 2017USD ($)	Jun. 30, 2018USD ($)aircraft	Jun. 30, 2017USD ($)
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Rent Expense	$ 137	$ 123	$ 290	$ 261
B-737 [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Committed to Purchase (in Aircraft) | aircraft	41		41
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	9		9
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	18		18
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	11		11
Property Subject to Operating Lease [Member] | E175 [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Number of units involved in lease contracts | aircraft	29		29
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	6		6
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	$ 32		$ 32
2,019	65		65
2,020	68		68
2,021	64		64
2,022	52		52
Thereafter	38		38
Total	319		319
Aircraft Commitments [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Remainder of 2018	467		467
2,019	558		558
2,020	515		515
2,021	562		562
2,022	304		304
Thereafter	141		141
Total	2,547		2,547
Capacity Purchase Agreements [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Remainder of 2018	67		67
2,019	138		138
2,020	145		145
2,021	166		166
2,022	174		174
Thereafter	1,205		1,205
Total	1,895		1,895
Aircraft Leases [Member]
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Remainder of 2018	177		177
2,019	349		349
2,020	323		323
2,021	282		282
2,022	264		264
Thereafter	1,071		1,071
Total	2,466		2,466
Facility Leases [Member]
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Remainder of 2018	38		38
2,019	68		68
2,020	61		61
2,021	52		52
2,022	33		33
Thereafter	139		139
Total	$ 391		$ 391

SHAREHOLDERS' EQUITY, CASH DIVI

SHAREHOLDERS' EQUITY, CASH DIVIDEND (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Equity [Abstract]
Cash dividend declared per share (usd per share)	$ 0.32	$ 0.3	$ 0.64	$ 0.60
Payments of Dividends	$ 40		$ 79	$ 74

SHAREHOLDERS' EQUITY, COMMON ST

SHAREHOLDERS' EQUITY, COMMON STOCK REPURCHASE (Details) - 2015 1 Billion Repurchase Program [Member] - USD ($) $ in Millions	3 Months Ended		6 Months Ended		31 Months Ended	34 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Mar. 31, 2018	Jun. 30, 2018	Aug. 31, 2015
Class of Stock [Line Items]
Stock repurchase program, authorized amount							$ 1,000
Stock repurchased during period (shares)						5,483,102
Value of stock repurchased during period					$ 413
Shares	204,078	256,680	389,739	256,680
Amount	$ 13	$ 22	$ 25	$ 22

SHAREHOLDERS' EQUITY, ACCUMULAT

SHAREHOLDERS' EQUITY, ACCUMULATED OTHER COMPREHENSIVE LOSS (Details) - USD ($) $ in Millions	Jan. 01, 2018	Jun. 30, 2018	Dec. 31, 2017
Equity [Abstract]
Related to marketable securities		$ (17)	$ (5)
Related to employee benefit plans		(425)	(376)
Related to interest rate derivatives		7	1
Total		$ (435)	$ (380)
Reclassification from AOCI to retained earnings	$ 62

OPERATING SEGMENT INFORMATION42

OPERATING SEGMENT INFORMATION (Details) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018USD ($)	Jun. 30, 2017USD ($)	Jun. 30, 2018USD ($)segment	Jun. 30, 2017USD ($)
Segment Reporting Information [Line Items]
Number of Operating Segments | segment			3
Operating Revenues
Total Operating Revenues	$ 2,156	$ 2,102	$ 3,988	$ 3,842
Operating expenses
Operating Expenses, Excluding Fuel	1,410	1,271	2,804	2,515
Economic fuel	475	344	884	683
Total Operating Expenses	1,885	1,615	3,688	3,198
Nonoperating Income (Expense)
Interest income	10	9	18	16
Interest expense	(25)	(26)	(49)	(51)
Interest Costs Capitalized	4	4	9	8
Other	(1)	0	(13)	(1)
Nonoperating Income (Expense) Total	(12)	(13)	(35)	(28)
Income (loss) before income tax	259	474	265	616
Air Group Adjusted [Member]
Operating Revenues
Total Operating Revenues	2,156	2,102	3,988	3,842
Operating expenses
Operating Expenses, Excluding Fuel	1,371	1,247	2,734	2,452
Economic fuel	497	342	919	671
Total Operating Expenses	1,868	1,589	3,653	3,123
Nonoperating Income (Expense)
Interest income	10	9	18	16
Interest expense	(25)	(26)	(49)	(51)
Interest Costs Capitalized	4	4	9	8
Other	(1)	0	(13)	(1)
Nonoperating Income (Expense) Total	(12)	(13)	(35)	(28)
Income (loss) before income tax	276	500	300	691
Alaska Mainline [Member]
Operating Revenues
Total Operating Revenues	1,859	1,823	3,438	3,327
Operating expenses
Operating Expenses, Excluding Fuel	1,135	1,030	2,266	2,030
Economic fuel	432	304	799	596
Total Operating Expenses	1,567	1,334	3,065	2,626
Nonoperating Income (Expense)
Interest income	13	10	24	17
Interest expense	(22)	(24)	(44)	(47)
Interest Costs Capitalized	4	3	8	7
Other	1	0	(4)	(1)
Nonoperating Income (Expense) Total	(4)	(11)	(16)	(24)
Income (loss) before income tax	288	478	357	677
Alaska Regional [Member]
Operating Revenues
Total Operating Revenues	296	278	548	513
Operating expenses
Operating Expenses, Excluding Fuel	249	206	488	406
Economic fuel	65	38	120	75
Total Operating Expenses	314	244	608	481
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	(9)	0
Nonoperating Income (Expense) Total	(2)	0	(9)	0
Income (loss) before income tax	(20)	34	(69)	32
Horizon [Member]
Operating Revenues
Total Operating Revenues	138	109	249	207
Operating expenses
Operating Expenses, Excluding Fuel	123	116	227	219
Economic fuel	0	0	0	0
Total Operating Expenses	123	116	227	219
Nonoperating Income (Expense)
Interest income	0	0	0	0
Interest expense	(5)	(3)	(10)	(5)
Interest Costs Capitalized	0	1	1	1
Other	0	0	0	0
Nonoperating Income (Expense) Total	(5)	(2)	(9)	(4)
Income (loss) before income tax	10	(9)	13	(16)
Intersegment Elimination [Member]
Operating Revenues
Total Operating Revenues	(137)	(108)	(247)	(205)
Operating expenses
Operating Expenses, Excluding Fuel	(136)	(105)	(247)	(203)
Economic fuel	0	0	0	0
Total Operating Expenses	(136)	(105)	(247)	(203)
Nonoperating Income (Expense)
Interest income	(3)	(1)	(6)	(1)
Interest expense	2	1	5	1
Interest Costs Capitalized	0	0	0	0
Other	0	0	0	0
Nonoperating Income (Expense) Total	(1)	0	(1)	0
Income (loss) before income tax	(2)	(3)	(1)	(2)
Special Revenue and Charges [Member]
Operating Revenues
Total Operating Revenues	0	0	0	0
Operating expenses
Operating Expenses, Excluding Fuel	39	24	70	63
Economic fuel	(22)	2	(35)	12
Total Operating Expenses	17	26	35	75
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	(17)	(26)	(35)	(75)
Passenger [Member]
Operating Revenues
Revenue from contract with customer, including assessed taxes	1,997	1,945	3,682	3,547
Passenger [Member] | Air Group Adjusted [Member]
Operating Revenues
Revenue from contract with customer, including assessed taxes	1,997	1,945	3,682	3,547
Passenger [Member] | Alaska Mainline [Member]
Operating Revenues
Revenue from contract with customer, including assessed taxes	1,711	1,677	3,153	3,052
Passenger [Member] | Alaska Regional [Member]
Operating Revenues
Revenue from contract with customer, including assessed taxes	286	268	529	495
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	137	108	247	205
Capacity Purchase Agreements [Member] | Intersegment Elimination [Member]
Operating Revenues
Revenue from contract with customer, including assessed taxes	(137)	(108)	(247)	(205)
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	108	109	215	209
Mileage plan other revenue [Member] | Air Group Adjusted [Member]
Operating Revenues
Revenue from contract with customer, including assessed taxes	108	109	215	209
Mileage plan other revenue [Member] | Alaska Mainline [Member]
Operating Revenues
Revenue from contract with customer, including assessed taxes	99	101	197	194
Mileage plan other revenue [Member] | Alaska Regional [Member]
Operating Revenues
Revenue from contract with customer, including assessed taxes	9	8	18	15
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	51	48	91	86
Cargo and Freight [Member] | Air Group Adjusted [Member]
Operating Revenues
Revenue from contract with customer, including assessed taxes	51	48	91	86
Cargo and Freight [Member] | Alaska Mainline [Member]
Operating Revenues
Revenue from contract with customer, including assessed taxes	49	45	88	81
Cargo and Freight [Member] | Alaska Regional [Member]
Operating Revenues
Revenue from contract with customer, including assessed taxes	1	2	1	3
Cargo and Freight [Member] | Horizon [Member]
Operating Revenues
Revenue from contract with customer, including assessed taxes	1	1	2	2
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	Jun. 30, 2018	Dec. 31, 2017
Total assets	$ 11,055	$ 10,746
Alaska Airlines [Member]
Total assets	15,334	16,663
Horizon [Member]
Total assets	1,039	929
Parent [Member]
Total assets	$ (5,318)	$ (6,846)