Alaska Air (ALK) 10-K 11 Feb 16 2015 FY Annual report Financial data

DOCUMENT AND ENTITY INFORMATION

DOCUMENT AND ENTITY INFORMATION - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2015	Jan. 31, 2016	Jun. 30, 2015
Entity Information [Line Items]
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
Document Type	10-K
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Common Stock, Shares Outstanding		124,729,056
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 8.2
Document Period End Date	Dec. 31, 2015

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Current Assets
Cash and cash equivalents	$ 73	$ 107
Marketable securities	1,255	1,110
Total cash and marketable securities	1,328	1,217
Receivables - less allowance for doubtful accounts of $1 and $1	212	259
Inventories and supplies - net	51	58
Prepaid expenses and other current assets	72	105
Total Current Assets	1,663	1,639
Property and Equipment
Aircraft and other flight equipment	5,690	5,165
Other property and equipment	955	896
Deposits for future flight equipment	771	555
Property and Equipment Total	7,416	6,616
Less accumulated depreciation and amortization	2,614	2,317
Total Property and Equipment - Net	4,802	4,299
Other Assets	68	126
Total Assets	6,533	6,064
Current Liabilities
Accounts payable	63	62
Accrued wages, vacation and payroll taxes	298	276
Other accrued liabilities	661	585
Air traffic liability	669	631
Current portion of long-term debt	115	117
Total Current Liabilities	1,806	1,671
Long-Term Debt, Net of Current Portion	571	686
Other Liabilities and Credits
Deferred income taxes	682	633
Deferred revenue	431	374
Obligation for pension and postretirement medical benefits	270	246
Other liabilities	362	327
Other Liabilities and Credits Totals	$ 1,745	$ 1,580
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: 200,000,000 shares, Issued: 2015 - 128,442,099 shares; 2014 - 131,556,573 shares, Outstanding: 2015 - 125,175,325 shares; 2014 - 131,481,473 shares	1	1
Capital in excess of par value	73	296
Treasury stock (common), at cost: 2015 - 3,266,774 shares; 2014 - 75,100 shares	(250)	(4)
Accumulated other comprehensive loss	(303)	(310)
Retained earnings	2,890	2,144
Shareholders' Equity Total	2,411	2,127
Total Liabilities and Shareholders' Equity	$ 6,533	$ 6,064

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Allowance for doubtful accounts	$ 1	$ 1
Stockholders' Equity:
Preferred Stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	128,442,099	131,556,573
Common Stock, Shares, Outstanding	125,175,325	131,481,473
Treasury Stock, Shares	3,266,774	75,100

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Operating Revenues
Passenger, Mainline	$ 3,939	$ 3,774	$ 3,490
Passenger, Regional	854	805	777
Total passenger revenue	4,793	4,579	4,267
Freight and mail	108	114	113
Other - net	697	675	584
Special Revenue	0	0	192
Total Operating Revenues	5,598	5,368	5,156
Operating Expenses
Wages and benefits	1,254	1,136	1,086
Variable incentive pay	120	116	105
Aircraft fuel, including hedging gains and losses	954	1,418	1,467
Aircraft maintenance	253	229	247
Aircraft rent	105	110	119
Landing fees and other rentals	296	279	262
Contracted services	214	196	176
Selling expenses	211	199	179
Depreciation and amortization	320	294	270
Food and beverage service	113	93	84
Third-party regional carrier expense	72	58	45
Other	356	308	278
Special Item	32	(30)	0
Total Operating Expenses	4,300	4,406	4,318
Operating Income	1,298	962	838
Nonoperating income (expense)
Interest income	21	21	18
Interest expense	(42)	(48)	(56)
Interest Costs Capitalized Adjustment	34	20	21
Other - net	1	20	(5)
Nonoperating Income (Expense) Total	14	13	(22)
Income (loss) before income tax	1,312	975	816
Income tax expense	464	370	308
Net Income	$ 848	$ 605	$ 508
Basic Earnings Per Share:	$ 6.61	$ 4.47	$ 3.63
Diluted Earnings Per Share:	$ 6.56	$ 4.42	$ 3.58
Shares used for computation:
Basic	128,373	135,445	139,910
Diluted	129,372	136,801	141,878
Common Stock, Dividends, Per Share, Declared	$ 0.80	$ 0.50	$ 0.20

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE OPERATIONS - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Net Income	$ 848	$ 605	$ 508
Related to marketable securities:
Unrealized holding gains (losses) arising during the period	(6)	2	(9)
Reclassification of (gains) losses into Other-net nonoperating income (expense)	1	(2)	(2)
Income tax benefit (expense)	2	0	4
Marketable securities, net of tax	(3)	0	(7)
Related to employee benefit plans:
Actuarial gains/(losses) related to pension and other post retirement benefit plans	10	(210)	358
Reclassification of net pension expense into Wages and benefits	14	9	42
Income tax benefit (expense)	(14)	76	(150)
Employee benefit plans, net of tax	10	(125)	250
Related to interest rate derivative instruments:
Unrealized holding gains (losses) arising during the period	(5)	(8)	10
Reclassification of (gains) losses into Aircraft rent	6	6	6
Income tax benefit (expense)	(1)	0	(6)
Interest rate derivative instruments, net of tax	0	(2)	10
Other comprehensive loss	7	(127)	253
Comprehensive income	$ 855	$ 478	$ 761

CONSOLIDATED STATEMENTS OF SHAR

CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) $ in Millions	Total	Common Stock	Capital in Excess of Par Value	Treasury Stock, at Cost	Accumulated Other Comprehensive Loss	Retained Earnings
Stockholders' Equity at Dec. 31, 2012	$ 1,421	$ 1	$ 729	$ 0	$ (436)	$ 1,127
Common Stock Outstanding at Dec. 31, 2012		140,754,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	508					508
Other comprehensive loss	$ 253				253
Common stock repurchase (in shares)	(4,984,186)	(4,984,000)
Common stock repurchase	$ (159)		(157)	(2)
Stock-based compensation	16		16
Cash dividend declared	(28)					(28)
Stock issued for employee stock purchase plan (in shares)		342,000
Stock issued for employee stock purchase plan	6		6
Stock issued under stock plans (in shares)		1,380,000
Stock issued under stock plans	12		12
Stockholders' Equity at Dec. 31, 2013	2,029	$ 1	606	(2)	(183)	1,607
Common Stock Outstanding at Dec. 31, 2013		137,492,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	605					605
Other comprehensive loss	$ (127)				(127)
Common stock repurchase (in shares)	(7,316,731)	(7,317,000)
Common stock repurchase	$ (348)		(346)	(2)
Stock-based compensation	16		16
Cash dividend declared	(68)					(68)
Stock issued for employee stock purchase plan (in shares)		299,000
Stock issued for employee stock purchase plan	9		9
Stock issued under stock plans (in shares)		1,007,000
Stock issued under stock plans	11		11
Stockholders' Equity at Dec. 31, 2014	$ 2,127	$ 1	296	(4)	(310)	2,144
Common Stock Outstanding at Dec. 31, 2014	131,481,473	131,481,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	$ 848					848
Other comprehensive loss	$ 7				7
Common stock repurchase (in shares)	(7,208,328)	(7,208,000)
Common stock repurchase	$ (505)		(259)	(246)
Stock-based compensation	17		17
Cash dividend declared	(102)					(102)
Stock issued for employee stock purchase plan (in shares)		281,000
Stock issued for employee stock purchase plan	13		13
Stock issued under stock plans (in shares)		621,000
Stock issued under stock plans	6		6
Stockholders' Equity at Dec. 31, 2015	$ 2,411	$ 1	$ 73	$ (250)	$ (303)	$ 2,890
Common Stock Outstanding at Dec. 31, 2015	125,175,325	125,175,000

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cash flows from operating activities:
Net Income	$ 848	$ 605	$ 508
Adjustments to reconcile net income to net cash provided by operating activities:
Special mileage plan accounting adjustment	0	0	(192)
Depreciation and amortization	320	294	270
Stock-based compensation and other	25	6	32
Changes in certain assets and liabilities:
Changes in deferred income taxes	(56)	(114)	(146)
(Increase) decrease in accounts receivable	47	(110)	(19)
Increase (decrease) in air traffic liability	38	67	29
Increase (decrease) in deferred revenue	57	40	84
Increase (Decrease) in Pension Plan Obligations	36	(18)	62
Other - net	157	32	148
Pension contribution	0	0	87
Net cash provided by operating activities	1,584	1,030	981
Property and equipment additions:
Aircraft and aircraft purchase deposits	(681)	(498)	(487)
Other flight equipment	(79)	(131)	(41)
Other property and equipment	(71)	(65)	(38)
Total property and equipment additions	(831)	(694)	(566)
Purchases of marketable securities	(1,327)	(949)	(1,218)
Sales and maturities of marketable securities	1,175	1,092	1,089
Proceeds from disposition of assets and changes in restricted deposits	53	10	(3)
Net cash used in investing activities	(930)	(541)	(698)
Cash flows from financing activities:
Proceeds from issuance of long-term debt	0	51	0
Long-term debt payments	(116)	(119)	(161)
Common stock repurchases	(505)	(348)	(159)
Cash dividend paid	(102)	(68)	(28)
Other financing activities	35	22	23
Net cash used in financing activities	(688)	(462)	(325)
Net increase (decrease) in cash and cash equivalents	(34)	27	(42)
Cash and cash equivalents at beginning of year	107	80	122
Cash and cash equivalents at end of year	73	107	80
Cash paid during the year for:
Interest (net of amount capitalized)	8	28	35
Income taxes	$ 349	$ 326	$ 149

GENERAL AND SUMMARY OF SIGNIFIC

GENERAL AND SUMMARY OF SIGNIFICANT ACCOUNTING	12 Months Ended
	Dec. 31, 2015
Accounting Policies [Abstract]
GENERAL AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	NOTE 1. GENERAL AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Organization and Basis of Presentation The consolidated financial statements include the accounts of Alaska Air Group, Inc. (Air Group or the Company) and its subsidiaries, Alaska Airlines, Inc. (Alaska) and Horizon Air Industries, Inc. (Horizon), through which the Company conducts substantially all of its operations. All significant intercompany balances and transactions have been eliminated. These financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America and their preparation requires the use of management’s estimates. Actual results may differ from these estimates. Certain reclassifications have been made to prior year financial statements to conform to classifications used in the current year. Cash and Cash Equivalents 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 market value. The Company reduces cash balances when funds are disbursed. Due to the time delay in funds clearing the banks, the Company normally maintains a negative balance in its cash disbursement accounts, which is reported as a current liability. The amount of the negative cash balance was $12 million and $7 million at December 31, 2015 and 2014 , respectively, and is included in accounts payable, with the change in the balance during the year included in other financing activities in the consolidated statements of cash flows. The Company has restricted cash balances 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. Marketable Securities Investments with original maturities of greater than three months and remaining maturities of less than one year are classified as short-term investments. Investments with maturities beyond one year may be classified as short-term based on their highly liquid nature and because such marketable securities represent the investment of cash that is available for current operations. All cash equivalents and short-term investments are classified as available-for-sale and realized gains and losses are recorded using the specific identification method. Changes in market value, excluding other-than-temporary impairments, are reflected in accumulated other comprehensive loss (AOCL). Investments are considered to be impaired when a decline in fair value is judged to be other-than-temporary. The Company uses a systematic methodology that considers available quantitative and qualitative evidence in evaluating potential impairment. If the cost of an investment exceeds its fair value, management evaluates, among other factors, general market conditions, credit quality of debt instrument issuers, the duration and extent to which the fair value is less than cost, our intent and ability to hold, or plans to sell, the investment. Once a decline in fair value is determined to be other-than-temporary, an impairment charge is recorded to Other-net in the consolidated statements of operations and a new cost basis in the investment is established. Receivables Receivables are due on demand and consist primarily of airline traffic (including credit card) receivables, Mileage Plan™ partners, amounts due from other airlines related to interline agreements, government tax authorities, and other miscellaneous amounts due to the Company, and are net of an allowance for doubtful accounts. Management determines the allowance for doubtful accounts based on known troubled accounts and historical experience applied to an aging of accounts. Inventories and Supplies—net Expendable aircraft parts, materials and supplies are stated at average cost and are included in inventories and supplies — net. An obsolescence allowance for expendable parts is accrued based on estimated lives of the corresponding fleet type and salvage values. The allowance for all non-surplus expendable inventories was $ 37 million and $34 million at December 31, 2015 and 2014 , respectively. Inventory and supplies — net also includes fuel inventory of $ 14 million and $21 million at December 31, 2015 and 2014 , respectively. Repairable and rotable aircraft parts inventories are included in flight equipment. Property, Equipment and Depreciation Property and equipment are recorded at cost and depreciated using the straight-line method over their estimated useful lives less an estimated salvage value, which are as follows: Aircraft and related flight equipment: Boeing 737 aircraft 20 years Bombardier Q400 15 years Buildings 25-30 years Minor building and land improvements 10 years Capitalized leases and leasehold improvements Shorter of lease term or estimated useful life Computer hardware and software 3-5 years Other furniture and equipment 5-10 years Salvage values used for aircraft are 10% of the fair value, but as aircraft near the end of their useful lives, we update the salvage value estimates based on current market conditions and expected use of the aircraft. “Related flight equipment” includes rotable and repairable spare inventories, which are depreciated over the associated fleet life unless otherwise noted. Capitalized interest is based on the Company’s weighted-average borrowing rate, is added to the cost of the related asset, and is depreciated over the estimated useful life of the asset. Maintenance and repairs, other than engine maintenance on some B737-700 and -900 engines, are expensed when incurred. Major modifications that extend the life or improve the usefulness of aircraft are capitalized and depreciated over their estimated period of use. Maintenance on some B737-700 and -900 engines is covered under power-by-the-hour agreements with third parties, whereby the Company pays a determinable amount, and transfers risk, to a third party. The Company expenses the contract amounts based on engine usage. The Company evaluates long-lived assets to be held and used for impairment whenever events or changes in circumstances indicate that the total carrying amount of an asset or asset group may not be recoverable. The Company groups assets for purposes of such reviews at the lowest level for which identifiable cash flows of the asset group are largely independent of the cash flows of other groups of assets and liabilities. An impairment loss is considered when estimated future undiscounted cash flows expected to result from the use of the asset or asset group and its eventual disposition are less than its carrying amount. If the asset or asset group is not considered recoverable, a write-down equal to the excess of the carrying amount over the fair value will be recorded. Internally Used Software Costs The Company capitalizes costs to develop internal-use software that are incurred in the application development stage. Amortization commences when the software is ready for its intended use and the amortization period is the estimated useful life of the software, generally three to five years. Capitalized costs primarily include contract labor and payroll costs of the individuals dedicated to the development of internal-use software. Deferred Revenue Deferred revenue results primarily from the sale of Mileage Plan™ miles to third-parties. This revenue is recognized when award transportation is provided or over the term of the applicable agreement. Operating Leases The Company leases aircraft, airport and terminal facilities, office space, and other equipment under operating leases. Some of these lease agreements contain rent escalation clauses or rent holidays. For scheduled rent escalation clauses during the lease terms or for rental payments commencing at a date other than the date of initial occupancy, the Company records minimum rental expenses on a straight-line basis over the terms of the leases in the consolidated statements of operations. Leased Aircraft Return Costs Cash payments associated with returning leased aircraft are accrued when it is probable that a cash payment will be made and that amount is reasonably estimable. Any accrual is based on the time remaining on the lease, planned aircraft usage and the provisions included in the lease agreement, although the actual amount due to any lessor upon return will not be known with certainty until lease termination. As leased aircraft are returned, any payments are charged against the established accrual. The accrual is part of other current and long-term liabilities, and was $5 million and $1 million as of December 31, 2015 and December 31, 2014 , respectively. Revenue Recognition Passenger revenue is recognized when the passenger travels. Tickets sold but not yet used are reported as air traffic liability until travel or date of expiration. Air traffic liability includes approximately $42 million and $33 million related to credits for future travel, as of December 31, 2015 and December 31, 2014 , respectively. These credits are recognized into revenue either when the passenger travels or the date of expiration, which is twelve months from issuance. Commissions to travel agents and related fees are expensed when the related revenue is recognized. Passenger traffic commissions and related fees not yet recognized are included as a prepaid expense. 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. Due to complex pricing structures, refund and exchange policies, and interline agreements with other airlines, certain amounts are recognized as revenue using estimates regarding both the timing of the revenue recognition and the amount of revenue to be recognized. These estimates are based on the Company’s historical data. Freight and mail revenues are recognized when service is provided. Other - net revenues are primarily related to the Mileage Plan™ and they are recognized as described in the “Mileage Plan” paragraph below. Other - net also includes certain ancillary or non-ticket revenues, such as checked-bag fees, reservations fees, ticket change fees, on-board food and beverage sales, and to a much lesser extent commissions from car and hotel vendors, and from the sales of travel insurance. These items are recognized as revenue when the related services are provided. Airport lounge memberships are recognized as revenue over the membership period. Mileage Plan Alaska operates a frequent flier program (“Mileage Plan™”) that provides travel awards to members based on accumulated mileage. For miles earned by flying on Alaska or Horizon and through airline partners, the estimated cost of providing award travel is recognized as a selling expense and accrued as a liability as miles are earned and accumulated. Alaska also sells services, including miles for transportation, to non-airline partners, such as hotels, car rental agencies, and a major bank that offers Alaska Airlines affinity credit cards. The Company defers passenger revenue related to air transportation and certificates for discounted companion travel until the transportation is delivered. The deferred proceeds are recognized as passenger revenue for awards redeemed and flown on Alaska or Horizon, and as Other-net revenue for awards redeemed and flown on other airlines (less the cost paid to the other airlines based on contractual agreements). For the elements that represent use of the Alaska Airlines brand and access to frequent flier member lists and advertising, it is recognized as commission income in the period that those elements are sold and included in Other - net revenue in the consolidated statements of operations. Alaska’s Mileage Plan™ deferred revenue and liabilities on the consolidated balance sheets (in millions): 2015 2014 Current Liabilities: Other accrued liabilities $ 368 $ 343 Other Liabilities and Credits: Deferred revenue 427 367 Other liabilities 19 20 Total $ 814 $ 730 The amounts recorded in other accrued liabilities relate primarily to deferred revenue expected to be realized within one year, which includes Mileage Plan™ awards that have been issued but not yet flown for $ 37 million and $33 million at December 31, 2015 and 2014 , respectively. Alaska’s Mileage Plan™ revenue included in the consolidated statements of operations (in millions): 2015 2014 2013 Passenger revenues $ 267 $ 246 $ 208 Other-net revenues 329 295 256 Special mileage plan revenue (a) — — 192 Total Mileage Plan revenues $ 596 $ 541 $ 656 (a) Refer to Note 10 for further information. Other — net revenue includes commission revenues of $280 million , $261 million , and $213 million in 2015 , 2014 , and 2013 , respectively. Selling Expenses Selling expenses include credit card fees, global distribution systems charges, the estimated cost of Mileage Plan™ travel awards earned through air travel, advertising, promotional costs, commissions, and incentives. Advertising production costs are expensed the first time the advertising takes place. Advertising expense was $ 55 million , $49 million , and $28 million during the years ended December 31, 2015 , 2014 , and 2013 , respectively. Derivative Financial Instruments The Company's operations are significantly impacted by changes in aircraft fuel prices and interest rates. In an effort to manage our exposure to these risks, the Company periodically enters into fuel and interest rate derivative instruments. These derivative instruments are recognized at fair value on the balance sheet and changes in the fair value is recognized in AOCL or in the consolidated statements of operations, depending on the nature of the instrument. The Company does not hold or issue derivative fuel hedge contracts for trading purposes and does not apply hedge accounting. For cash flow hedges related to our interest rate swaps, the effective portion of the derivative represents the change in fair value of the hedge that offsets the change in fair value of the hedged item. To the extent the change in the fair value of the hedge does not perfectly offset the change in the fair value of the hedged item, the ineffective portion of the hedge is immediately recognized in interest expense. Fair Value Measurements Accounting standards define fair value as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. The standards also establish a fair value hierarchy, which requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. There are three levels of inputs that may be used to measure fair value: Level 1 - Quoted prices in active markets for identical assets or liabilities. Level 2 - Observable inputs other than Level 1 prices such as quoted prices for similar assets or liabilities, quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3 - Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. The Company has elected not to use the Fair Value Option for non-financial instruments, and accordingly those assets and liabilities are carried at amortized cost. For financial instruments, those assets and liabilities are carried at fair value and are determined based on the market approach or income approach depending upon the level of inputs used. Income Taxes The Company uses the asset and liability approach for accounting and reporting income taxes. Deferred tax assets and liabilities are recognized for future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases, and for operating loss and tax credit carryforwards. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in the period that includes the enactment date. A valuation allowance would be established, if necessary, for the amount of any tax benefits that, based on available evidence, are not expected to be realized. The Company accounts for unrecognized tax benefits in accordance with the accounting standards. Stock-Based Compensation Accounting standards require companies to recognize as expense the fair value of stock options and other equity-based compensation issued to employees as of the grant date. These standards apply to all stock awards that the Company grants to employees as well as the Company’s Employee Stock Purchase Plan (ESPP), which features a look-back provision and allows employees to purchase stock at a 15% discount. All stock-based compensation expense is recorded in wages and benefits in the consolidated statements of operations. Earnings Per Share (EPS) Diluted EPS is calculated by dividing net income by the average common shares outstanding plus 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. In 2015 , 2014 , and 2013 , antidilutive stock options excluded from the calculation of EPS were not material. Recently Issued Accounting Pronouncements In May 2014, the FASB issued Accounting Standard Update 2014-09, "Revenue from Contracts with Customers" (ASU 2014-09), which requires an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers. The ASU will replace most existing revenue recognition guidance in U.S. GAAP when it becomes effective. The new standard is effective for the Company on January 1, 2018. The standard permits the use of either the retrospective or cumulative effect transition method. At this time, the Company believes the most significant impact to the financial statements will be in Mileage Plan revenues and liabilities. The Company currently uses the incremental cost approach for miles earned through travel. This standard eliminates that option and the Company will be required to increase its liability for earned miles through a relative selling price model. The Company has not evaluated the full impact of the standard, although application is expected to result in a material increase to Deferred Revenue. The Company has not yet selected a transition method. In July 2015, FASB issued ASU 2015-07, Disclosures for Investments in Certain Entities that Calculate Net Asset Value per Share, which removes the requirement for companies to disclose the fair value hierarchy for assets calculated at net asset value per share in common commingled trusts, for example. This standard is effective January 1, 2016 for the Company. However, early adoption is permitted and the Company has elected to adopt this standard in 2015. The Company's pension assets are invested in common commingled trusts and, as such, the Company has removed the disclosure of the fair value hierarchy for pension assets in common commingled trusts. In November 2015, FASB issued ASU 2015-17, Balance Sheet Classification of Deferred Taxes, which simplifies the presentation of deferred income taxes. This ASU requires that net deferred tax assets and liabilities be classified as noncurrent on the balance sheet. The Company has elected to early adopt ASU 2015-17 as of December 31, 2015, as permitted by the FASB, and has retrospectively applied the standard. This has resulted in a reduction of total current assets and corresponding reduction of other liabilities of $117 million as of December 31, 2014.

CASH, CASH EQUIVALENTS AND MARK

CASH, CASH EQUIVALENTS AND MARKETABLE SECURITIES	12 Months Ended
	Dec. 31, 2015
Cash, Cash Equivalents, and Short-term Investments [Abstract]
CASH, CASH EQUIVALENTS AND MARKETABLE SECURITIES	NOTE 2. CASH, CASH EQUIVALENTS AND MARKETABLE SECURITIES Components for cash, cash equivalents and marketable securities (in millions): December 31, 2015 Cost Basis Unrealized Gains Unrealized Losses Fair Value Cash $ 4 $ — $ — $ 4 Cash equivalents 69 — — 69 Cash and cash equivalents 73 — — 73 U.S. government and agency securities 254 — (1 ) 253 Foreign government bonds 31 — — 31 Asset-backed securities 130 — — 130 Mortgage-backed securities 117 — (1 ) 116 Corporate notes and bonds 711 1 (4 ) 708 Municipal securities 17 — — 17 Marketable securities 1,260 1 (6 ) 1,255 Total $ 1,333 $ 1 $ (6 ) $ 1,328 December 31, 2014 Cost Basis Unrealized Gains Unrealized Losses Fair Value Cash $ 4 $ — $ — $ 4 Cash equivalents 103 — — 103 Cash and cash equivalents 107 — — 107 U.S. government and agency securities 166 — — 166 Foreign government bonds 25 — — 25 Asset-backed securities 130 — — 130 Mortgage-backed securities 127 — (1 ) 126 Corporate notes and bonds 644 3 (2 ) 645 Municipal securities 18 — — 18 Marketable securities 1,110 3 (3 ) 1,110 Total $ 1,217 $ 3 $ (3 ) $ 1,217 Unrealized losses from fixed-income securities are primarily attributable to changes in interest rates. Management does not believe any remaining unrealized losses represent other-than-temporary impairments based on our evaluation of available evidence as of December 31, 2015 . Activity for marketable securities (in millions): 2015 2014 2013 Proceeds from sales and maturities $ 1,175 $ 1,092 $ 1,089 Gross realized gains 2 4 4 Gross realized losses (3 ) (2 ) (2 ) Maturities for marketable securities (in millions): December 31, 2015 Cost Basis Fair Value Due in one year or less $ 182 $ 182 Due after one year through five years 1,055 1,050 Due after five years through 10 years 14 14 Due after 10 years 9 9 Total $ 1,260 $ 1,255

DERIVATIVE INSTRUMENTS

DERIVATIVE INSTRUMENTS	12 Months Ended
	Dec. 31, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
DERIVATIVE INSTRUMENTS	NOTE 3. DERIVATIVE INSTRUMENTS Fuel Hedge Contracts The Company’s operations are inherently dependent upon the price and availability of aircraft fuel. To manage economic risks associated with fluctuations in aircraft fuel prices, the Company periodically enters into call options for crude oil. As of December 31, 2015 , the Company had fuel hedge contracts outstanding covering 273 million gallons of crude oil that will be settled from January 2016 to June 2017 . Refer to the contractual obligations and commitments section of Item 7 for further information. Interest Rate Swap Agreements The Company has interest rate swap agreements with a third party designed to hedge the volatility of the underlying variable interest rate in the Company's aircraft lease agreements for six Boeing 737-800 aircraft. The agreements stipulate that the Company pay a fixed interest rate over the term of the contract and receive a floating interest rate. All significant terms of the swap agreement match the terms of the lease agreements, including interest-rate index, rate reset dates, termination dates and underlying notional values. The agreements expire from February 2020 through March 2021 to coincide with the lease termination dates. Fair Values of Derivative Instruments Fair values of derivative instruments on the consolidated balance sheet (in millions): 2015 2014 Derivative Instruments Not Designated as Hedges Fuel hedge contracts Prepaid expenses and other current assets $ 2 $ 3 Other assets 2 4 Derivative Instruments Designated as Hedges Interest rate swaps Other accrued liabilities (5 ) (6 ) Other liabilities (13 ) (13 ) Losses in accumulated other comprehensive loss (AOCL) (18 ) (19 ) The net cash received (paid) for new fuel hedge positions and settlements was $(17) million , $(9) million , and $5 million during 2015 , 2014 , and 2013 , respectively. Pretax effect of derivative instruments on earnings and AOCL (in millions): 2015 2014 2013 Derivative Instruments Not Designated as Hedges Fuel hedge contracts Gains (losses) recognized in aircraft fuel expense $ (19 ) $ (18 ) $ (44 ) Derivative Instruments Designated as Hedges Interest rate swaps Gains (losses) recognized in aircraft rent (6 ) (6 ) (6 ) Gains (losses) recognized in other comprehensive income (OCI) (5 ) (8 ) 10 The amounts shown as recognized in aircraft rent for cash flow hedges (interest rate swaps) represent the realized losses transferred out of AOCL to aircraft rent. The amounts shown as recognized in OCI are prior to the losses recognized in aircraft rent during the period. The Company expects $5 million to be reclassified from OCI to aircraft rent within the next twelve months. Credit Risk and Collateral The Company is exposed to credit losses in the event of non-performance by counterparties to these derivative instruments. To mitigate exposure, the Company periodically reviews the risk of counterparty nonperformance by monitoring the absolute exposure levels and credit ratings. The Company maintains security agreements with a number of its counterparties which may require the Company to post collateral if the fair value of the selected derivative instruments fall below specified thresholds. The posted collateral does not offset the fair value of the derivative instruments and is included in "Prepaid expenses and other current assets" on the consolidated balance sheet. The amount posted as collateral for these contracts is not material to the consolidated balance sheets as of December 31, 2015 , and 2014 .

FAIR VALUE MEASUREMENTS

FAIR VALUE MEASUREMENTS	12 Months Ended
	Dec. 31, 2015
Fair Value Disclosures [Abstract]
FAIR VALUE MEASUREMENTS	NOTE 4. FAIR VALUE MEASUREMENTS Fair Value of Financial Instruments on a Recurring Basis Fair values of financial instruments on the consolidated balance sheet (in millions): December 31, 2015 Level 1 Level 2 Total Assets Marketable securities U.S. government and agency securities $ 253 $ — $ 253 Foreign government bonds — 31 31 Asset-backed securities — 130 130 Mortgage-backed securities — 116 116 Corporate notes and bonds — 708 708 Municipal securities — 17 17 Derivative instruments Fuel hedge contracts Call options — 4 4 Liabilities Derivative instruments Interest rate swap agreements — (18 ) (18 ) December 31, 2014 Level 1 Level 2 Total Assets Marketable securities U.S. government and agency securities $ 166 $ — $ 166 Foreign government bonds — 25 25 Asset-backed securities — 130 130 Mortgage-backed securities — 126 126 Corporate notes and bonds — 645 645 Municipal securities — 18 18 Derivative instruments Fuel hedge contracts Call options — 7 7 Liabilities Derivative instruments Interest rate swap agreements — (19 ) (19 ) The Company uses 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. Fuel hedge contracts that are not traded on a public exchange are Level 2 as the fair value is primarily based on inputs which are readily available in active markets or can be derived from information available in active markets. The fair value for 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. The Company has no other financial assets that are measured at fair value on a nonrecurring basis at December 31, 2015 . Fair Value of Other Financial Instruments The Company used the following methods and assumptions to determine the fair value of financial instruments that are not recognized at fair value as described below. Cash and Cash Equivalents : Carried at amortized costs which approximate fair value. Debt : The carrying amounts of the Company's variable-rate debt approximate fair values. For fixed-rate debt, the Company uses the income approach to determine the estimated fair value, by discounting cash flows using borrowing rates for comparable debt over the weighted 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 that is not carried at fair value on the consolidated balance sheet and the estimated fair value of long-term fixed-rate debt (in millions): 2015 2014 Carrying Amount $ 520 $ 614 Fair value 557 666

LONG-TERM DEBT

LONG-TERM DEBT	12 Months Ended
	Dec. 31, 2015
Debt Disclosure [Abstract]
LONG-TERM DEBT	NOTE 5. LONG-TERM DEBT Long-term debt obligations (in millions): 2015 2014 Fixed-rate notes payable due through 2024 $ 520 $ 614 Variable-rate notes payable due through 2025 166 189 Long-term debt 686 803 Less current portion 115 117 $ 571 $ 686 Weighted-average fixed-interest rate 5.7 % 5.7 % Weighted-average variable-interest rate 1.8 % 1.6 % All of the Company’s borrowings are secured by aircraft. During 2015 , the Company issued no new debt and made scheduled debt payments of $116 million . As of December 31, 2015 , none of the Company's borrowings were restricted by financial covenants. Long-term debt principal payments for the next five years and thereafter (in millions): Total 2016 $ 115 2017 121 2018 151 2019 114 2020 116 Thereafter 69 Total principal payments $ 686 Bank Line of Credit The Company has two $100 million credit facilities and one $52 million credit facility. All three facilities have variable interest rates based on LIBOR plus a specified margin. One of the $100 million facilities, which expires in September 2017, is secured by aircraft. The other $100 million facility, which expires in March 2017, is secured by certain accounts receivable, spare engines, spare parts and ground service equipment. The $52 million facility expires in October 2016 with a mechanism for annual renewal and is secured by two 737-800 aircraft. The Company has no immediate plans to borrow using any of these 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 December 31, 2015 .

INCOME TAXES

INCOME TAXES	12 Months Ended
	Dec. 31, 2015
Income Tax Disclosure [Abstract]
INCOME TAXES	NOTE 6. INCOME TAXES Deferred Income Taxes Deferred income taxes reflect the impact of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and such amounts for tax purposes. Primarily due to differences in depreciation rates for federal income tax purposes and for financial reporting purposes, the Company has generated a net deferred tax liability. Deferred tax (assets) and liabilities comprise the following (in millions): 2015 2014 Excess of tax over book depreciation $ 1,110 $ 1,042 Other—net 23 22 Gross deferred tax liabilities 1,133 1,064 Mileage Plan (208 ) (206 ) Inventory obsolescence (22 ) (20 ) Deferred gains (8 ) (10 ) Employee benefits (167 ) (166 ) Fuel hedge contracts (5 ) (5 ) Other—net (41 ) (24 ) Gross deferred tax assets (451 ) (431 ) Net deferred tax liabilities $ 682 $ 633 The Company has concluded that it is more likely than not that its deferred tax assets will be realizable and thus no valuation allowance has been recorded as of December 31, 2015 . This conclusion is based on the expected future reversals of existing taxable temporary differences, anticipated future taxable income, and the potential for future tax planning strategies to generate taxable income, if needed. The Company will continue to reassess the need for a valuation allowance during each future reporting period. Components of Income Tax Expense The components of income tax expense were as follows (in millions): 2015 2014 2013 Current tax expense: Federal $ 397 $ 229 $ 145 State 30 27 17 Total current 427 256 162 Deferred tax expense: Federal 60 103 131 State (23 ) 11 15 Total deferred 37 114 146 Income tax expense $ 464 $ 370 $ 308 Income Tax Rate Reconciliation Income tax expense reconciles to the amount computed by applying the U.S. federal rate of 35% to income before income tax and accounting change as follows (in millions): 2015 2014 2013 Income before income tax $ 1,312 $ 975 $ 816 Expected tax expense 459 341 286 Nondeductible expenses 4 4 4 State income taxes 19 25 21 State income sourcing (15 ) — — Other—net (3 ) — (3 ) Actual tax expense $ 464 $ 370 $ 308 Effective tax rate 35.4 % 37.9 % 37.7 % In the fourth quarter of 2015, the Company filed amended state tax returns for the years 2010 through 2013 to update the Company’s position on income sourcing in various states. These positions were also taken on 2014 filings and will be taken going forward. The cumulative benefit of this change is $26 million , net of federal impact and unrecognized tax benefits of $18 million . Uncertain Tax Positions The Company has identified its federal tax return and its state tax returns in Alaska, Oregon, and California as “major” tax jurisdictions. A summary of the Company's jurisdictions and the periods that are subject to examination are as follows: Jurisdiction Period Federal 2012 to 2014 Alaska 2012 to 2014 California 2010 to 2014 Oregon 2003 to 2014* *The 2003, 2004, 2008-2010 and 2011 Oregon tax returns are subject to examination only to the extent of net operating loss carryforwards from those years that were utilized in 2010 and later years. Changes in the liability for unrecognized tax benefits during 2015 , 2014 , and 2013 are as follows (in millions): 2015 2014 2013 Balance at January 1, $ 3 $ 2 $ 1 Additions based on tax positions and settlements related to the current year 19 1 1 Balance at December 31, $ 22 $ 3 $ 2 At December 31, 2015 , the total amount of unrecognized tax benefits is recorded as a liability, all of which impacts the effective tax rate. The Company added $19 million of reserves for uncertain tax positions in 2015, primarily due to changes in income sourcing for state income taxes. These uncertain tax positions could change as a result of the Company’s ongoing audits, settlement of issues, new audits and status of other taxpayer court cases and we cannot predict the timing of these actions. Due to the positions being taken in various jurisdictions, at the current time, an estimate of the range of reasonably possible outcomes cannot be made, beyond amounts currently accrued. No interest or penalties related to these tax positions were accrued as of December 31, 2015 .

EMPLOYEE BENEFIT PLANS

EMPLOYEE BENEFIT PLANS	12 Months Ended
	Dec. 31, 2015
Compensation and Retirement Disclosure [Abstract]
EMPLOYEE BENEFIT PLANS	NOTE 7. EMPLOYEE BENEFIT PLANS Four defined-benefit and five defined-contribution retirement plans cover various employee groups of Alaska and Horizon. The defined-benefit plans provide benefits based on an employee’s term of service and average compensation for a specified period of time before retirement. The qualified defined-benefit pension plans are closed to new entrants. Accounting standards require recognition of the overfunded or underfunded status of an entity’s defined-benefit pension and other postretirement plan as an asset or liability in the consolidated financial statements and requires recognition of the funded status in AOCL. Qualified Defined-Benefit Pension Plans The Company’s pension plans are funded as required by the Employee Retirement Income Security Act of 1974 (ERISA). The defined-benefit plan assets consist primarily of marketable equity and fixed-income securities. The Company uses a December 31 measurement date for these plans. Weighted average assumptions used to determine benefit obligations: 2015 2014 Discount rates (a) 4.55% to 4.69% 4.20% Rate of compensation increases (a) 2.06% to 2.65% 2.85% to 3.91% (a) Varies by plan and related work group. Weighted average assumptions used to determine net periodic benefit cost: 2015 2014 2013 Discount rate 4.20% 4.85% 3.95% Expected return on plan assets 6.50% 6.75% 7.25% Rate of compensation increases (a) 2.85% to 3.91% 2.90% to 3.93% 3.05% to 4.02% (a) Varies by plan and related work group. The discount rate was determined using current rates earned on high-quality, long-term bonds with maturities that correspond with the estimated cash distributions from the pension plans. At December 31, 2015 , the Company selected discount rates for each of the plans using a pool of higher-yielding bonds estimated to be more reflective of settlement rates, as management has taken steps to ultimately terminate or settle plans that are frozen and move toward freezing benefits in active plans in the future. In determining the expected return on plan assets, the Company assesses the current level of expected returns on risk-free investments (primarily government bonds), the historical level of the risk premium associated with the other asset classes in which the portfolio is invested and the expectations for future returns of each asset class. The expected return for each asset class is then weighted based on the target asset allocation to develop the expected long-term rate of return on assets assumption for the portfolio. Plan assets are invested in common commingled trust funds invested in equity and fixed income securities and in certain real estate assets. The asset allocation of the funds in the qualified defined-benefit plans, by asset category, is as follows: 2015 2014 Asset category: Domestic equity securities 28 % 33 % Non-U.S. equity securities 12 % 14 % Fixed income securities 55 % 53 % Real estate 5 % — % Plan assets 100 % 100 % The Company’s investment policy focuses on achieving maximum returns at a reasonable risk for pension assets over a full market cycle. In 2015, the Company separated the management of plan assets for the defined-benefit plan that covers the Company's non-union, management participants. This plan has been closed to new participants for several years and benefits were frozen effective January 1, 2014. These assets have a higher allocation to fixed income securities than the other plans. The Company uses a fund manager and invests in various asset classes to diversify risk. Target allocations for the primary asset classes based on current funded status are approximately: Domestic equities: 21% - 33% Non-U.S. equities: 7% - 17% Fixed income: 48% - 67% Real estate: 0% - 8% The Company determines the strategic allocation between equities, fixed income, and real estate based on current funded status and other characteristics of the plans. As the funded status improves, the Company increases the fixed income allocation of the portfolio, and decreases the equity allocation. Actual asset allocations are reviewed regularly and periodically rebalanced as appropriate. As of December 31, 2015 , all assets other than real estate were invested in common commingled trust funds. The Company uses the net asset values of these funds to determine fair value as allowed using the practical expediency method outlined in the accounting standards. Fair value estimates for real estate are calculated using the present value of expected future cash flows based on independent appraisals, local market conditions, and current and projected operating performance. Plan asset by fund category (in millions): 2015 2014 Fair Value Hierarchy Fund type: U.S. equity market fund 491 634 (a) Non-U.S. equity fund 208 272 (a) Credit bond index fund 953 190 (a) Government/credit bond index fund — 821 (a) Plan assets in common commingled trusts $ 1,652 $ 1,917 Real estate 85 — Level 3 Total plan assets $ 1,737 $ 1,917 (a) In accordance with Subtopic 820-10, certain investments that are measured at fair value using the net asset value per share practical expedient have not been classified in the fair value hierarchy. Changes in our Level 3 plan assets for the year ended December 31, 2015 included: Asset Category December 31, 2014 Balance Net Realized and Unrealized Gains/Losses Net Purchases, Issuances and Settlements Net Transfers Into/(Out of) Level 3 December 31, 2015 Balance Real Estate $ — 5 80 — $ 85 The following table sets forth the status of the qualified defined-benefit pension plans (in millions): 2015 2014 Projected benefit obligation (PBO) Beginning of year $ 2,050 $ 1,709 Service cost 41 33 Interest cost 84 81 Plan settlement (62 ) — Actuarial (gain) loss (140 ) 298 Benefits paid (75 ) (71 ) End of year $ 1,898 $ 2,050 Plan assets at fair value Beginning of year $ 1,917 $ 1,769 Actual return on plan assets (43 ) 219 Employer contributions — — Plan settlement (62 ) — Benefits paid (75 ) (71 ) End of year $ 1,737 $ 1,917 Funded status (unfunded) $ (161 ) $ (133 ) Percent funded 92 % 94 % The accumulated benefit obligation for the combined qualified defined-benefit pension was $1.8 billion and $1.9 billion at December 31, 2015 , and 2014 , respectively. The amounts recognized in the consolidated balance sheets (in millions): 2015 2014 Accrued benefit liability-long term $ 173 $ 133 Plan assets-long term (within noncurrent Other Assets) (12 ) — Total liability recognized $ 161 $ 133 The amounts not yet reflected in net periodic benefit cost and included in AOCL: 2015 2014 Prior service credit $ (11 ) $ (12 ) Net loss 499 514 Amount recognized in AOCL (pretax) $ 488 $ 502 The expected amortization of prior service credit and net loss from AOCL in 2016 is $(1) million and $25 million , respectively, for the qualified defined-benefit pension plans. Net pension expense for the qualified defined-benefit plans included the following components (in millions): 2015 2014 2013 Service cost $ 41 $ 33 $ 46 Interest cost 84 81 73 Expected return on assets (122 ) (117 ) (111 ) Amortization of prior service cost (1 ) (1 ) (1 ) Recognized actuarial loss 26 13 43 Settlement expense (special item) 14 — — Net pension expense $ 42 $ 9 $ 50 In 2015 , the Company recognized a settlement charge of $14 million related to lump sum settlements offered to terminated, vested plan participants. The result was a reduction in the projected benefit obligation of $62 million . The settlement charge reflects the remaining unamortized actuarial loss in AOCL associated with the settled obligation. There are no current statutory funding requirements for the Company’s plans in 2016 , nor does the Company expect to contribute to the qualified defined-benefit pension plans during 2016 . Future benefits expected to be paid over the next ten years under the qualified defined-benefit pension plans from the assets of those plans (in millions): 2016 $ 77 2017 86 2018 93 2019 96 2020 107 2021 - 2024 613 Nonqualified Defined-Benefit Pension Plan Alaska also maintains an unfunded, noncontributory defined-benefit plan for certain elected officers. This plan uses a December 31 measurement date. The assumptions used to determine benefit obligations and the net period benefit cost for the nonqualified defined-benefit pension plan are similar to those used to calculate the qualified defined-benefit pension plan. The plan's unfunded status, PBO, accumulated benefit obligation is immaterial. The net pension expense in prior year and expected future expense is also immaterial. Postretirement Medical Benefits The Company allows certain retirees to continue their medical, dental, and vision benefits by paying all or a portion of the active employee plan premium until eligible for Medicare, currently age 65. This results in a subsidy to retirees, because the premiums received by the Company are less than the actual cost of the retirees’ claims. The accumulated postretirement benefit obligation (APBO) for this subsidy is unfunded. The accumulated postretirement benefit obligation was $64 million and $81 million at December 31, 2015 and 2014 , respectively. The net periodic benefit cost was not material to the statement of operations. During 2014 , the Company made changes to the postretirement medical benefits for non-union personnel and certain labor groups to sunset the postretirement medical benefits effective in 2015. As a result of these changes, the Company recognized a partial curtailment gain of $25 million in 2014 . The curtailment gain included $5 million associated with an embedded sick leave subsidy. This subsidy was used to establish a new compensated absence liability. The net impact of the curtailment gain of $20 million is included in special items in the income statement. Defined-Contribution Plans The defined-contribution plans are deferred compensation plans under section 401(k) of the Internal Revenue Code. All of these plans require Company contributions. Total expense for the defined-contribution plans was $60 million , $54 million , and $44 million in 2015 , 2014 , and 2013 , respectively. The Company also has a noncontributory, unfunded defined-contribution plan for certain elected officers of the Company who are ineligible for the nonqualified defined-benefit pension plan. Amounts recorded as liabilities under the plan are not material to the consolidated balance sheet at December 31, 2015 and 2014 . Pilot Long-term Disability Benefits Alaska maintains a long-term disability plan for its pilots. The long-term disability plan does not have a service requirement. Therefore, the liability is calculated based on estimated future benefit payments associated with pilots that were assumed to be disabled on a long-term basis as of December 31, 2015 and does not include any assumptions for future disability. The liability includes the discounted expected future benefit payments and medical costs. The total liability was $19 million and $16 million , which was recorded net of a prefunded trust account of $2 million and $2 million , and included in long-term other liabilities on the consolidated balance sheets as of December 31, 2015 and December 31, 2014 , respectively. Employee Incentive-Pay Plans Alaska and Horizon have employee incentive plans that pay employees based on certain financial and operational metrics. These metrics are set and approved annually by the Compensation Committee of the Board of Directors. The aggregate expense under these plans in 2015 , 2014 and 2013 was $120 million , $116 million , and $105 million , respectively. The plans are summarized below: • Performance-Based Pay (PBP) is a program that rewards all employees. The program is based on four separate metrics related to Air Group profitability, safety, achievement of unit-cost goals, and employee engagement as measured by customer satisfaction. • The Operational Performance Rewards Program entitles all Air Group employees to quarterly payouts of up to $300 per person if certain operational and customer service objectives are met.

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	12 Months Ended
	Dec. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	NOTE 8. COMMITMENTS AND CONTINGENCIES Future minimum fixed payments for commitments as of December 31, 2015 (in millions): Aircraft Leases Facility Leases Aircraft Commitments Capacity Purchase Agreements 2016 $ 113 $ 92 $ 505 $ 67 2017 104 88 549 58 2018 98 41 444 60 2019 90 41 390 64 2020 81 38 327 68 Thereafter 467 142 418 554 Total $ 953 $ 442 $ 2,633 $ 871 Lease Commitments At December 31, 2015 , the Company had lease contracts for 27 B737 aircraft, 15 Q400 aircraft, 6 CRJ-700 aircraft (operated under the CPA with SkyWest) and 8 CRJ-700 aircraft that are subleased and operated by another carrier (i.e. not in the Company's fleet). The Company has 15 E175 aircraft lease commitments under the CPA with SkyWest, 5 of which are included in the fleet as of December 31, 2015. All lease contracts have remaining noncancelable lease terms ranging from 2016 to 2028 . The Company has the option to increase capacity flown by SkyWest with eight additional E175 aircraft with 2017 and 2018 delivery dates. In addition to the above lease commitments, the Company has contracted for eight E175 regional aircraft that will enter service in 2017. The majority of airport and terminal facilities are leased. Total rent expense for aircraft and facility leases was $295 million , $288 million , and $290 million , in 2015 , 2014 , and 2013 , respectively. Aircraft Commitments As of December 31, 2015 , the Company is committed to purchasing 68 B737 aircraft ( 31 B737-900ER aircraft and 37 B737 MAX aircraft, with deliveries in 2016 through 2022 ) and two Q400 aircraft, with deliveries in 2018 . In addition, the Company has options to purchase 46 B737 aircraft and 5 Q400 aircraft. Capacity Purchase Agreements (CPAs) At December 31, 2015 , Alaska had CPAs with three carriers, including the Company's wholly-owned subsidiary, Horizon. Horizon sells 100% of its capacity under a CPA with Alaska. In addition, Alaska has a CPA with PenAir to fly certain routes in the state of Alaska. Under these agreements, Alaska pays the carriers an amount which is based on a determination of their cost of operating those flights and other factors intended to approximate market rates for those services. Future payments (excluding Horizon) are based on minimum levels of flying by the third-party carriers, which could differ materially due to variable payments based on actual levels of flying and certain costs associated with operating flights such as fuel. During the second quarter Alaska signed an amendment to the CPA with SkyWest to remove the eight CRJ-700 aircraft out of regional operations and replace them with eight E175 aircraft. Six of these CRJ-700 aircraft are leased by the Company and two of the aircraft are owned by the Company. The E175 aircraft will be introduced into service throughout 2016, at which time the CRJ-700 aircraft will be removed from service. The CPA with SkyWest is a service contract that, in accordance with GAAP, includes embedded leases related to the aircraft operated under the agreement. Contingencies The Company is a party to routine litigation matters incidental to its business and with respect to which no material liability is expected. Management believes the ultimate disposition of these matters is not likely to materially affect the Company's financial position or results of operations. 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.

SHAREHOLDER'S EQUITY

SHAREHOLDER'S EQUITY	12 Months Ended
	Dec. 31, 2015
Equity [Abstract]
SHAREHOLDER'S EQUITY	NOTE 9. SHAREHOLDERS' EQUITY Common Stock Changes During the second quarter of 2014, shareholders voted to increase the number of authorized shares from 100 million to 200 million shares, and reduce the par value of common stock from $1 per share to $0.01 per share, and the Board of Directors declared a two-for-one stock split by means of a stock distribution. The additional shares were distributed on July 9, 2014, to the shareholders of record on June 23, 2014. Dividends During 2015 , the Board of Directors declared dividends of $0.80 per share. The Company paid dividends of $102 million to shareholders of record during 2015 . Subsequent to year-end, the Board of Directors declared a quarterly cash dividend of $0.275 per share to be paid on March 8, 2016 to shareholders of record as of February 23, 2016. This is a 38% increase from the most recent quarterly dividends of $0.20 per share. Common Stock Repurchase In August 2015 , the Board of Directors authorized a $1 billion share repurchase program, which does not have a set expiration date. In May 2014 , the Board of Directors authorized a $650 million share repurchase program, which was completed in October 2015 . In September 2012 , the Board of Directors authorized a $250 million share repurchase program, which was completed in July 2014. Share repurchase activity (in millions, except shares): 2015 2014 2013 Shares Amount Shares Amount Shares Amount 2015 $1 billion Repurchase Program 1,517,277 $ 120 — $ — — $ — 2014 $650 million Repurchase Program 5,691,051 $ 385 5,497,427 $ 265 — $ — 2012 $250 million Repurchase Program — — 1,819,304 83 4,984,186 159 Total 7,208,328 $ 505 7,316,731 $ 348 4,984,186 $ 159 Retirement of Treasury Shares In 2015 , the Company retired 4,016,654 common shares that had been held in treasury. At December 31, 2015 , the Company held 3,266,774 shares in treasury. Management does not anticipate retiring common shares held in treasury for the foreseeable future. Accumulated Other Comprehensive Loss (AOCL) AOCL consisted of the following (in millions, net of tax): 2015 2014 Related to marketable securities (3 ) — Related to employee benefit plans (288 ) (298 ) Related to interest rate derivatives (12 ) (12 ) $ (303 ) $ (310 )

SPECIAL ITEMS SPECIAL ITEMS

SPECIAL ITEMS SPECIAL ITEMS	12 Months Ended
	Dec. 31, 2015
SPECIAL ITEMS [Abstract]
Unusual or Infrequent Items Disclosure [Text Block]	NOTE 10. SPECIAL ITEMS Special Mileage Plan Revenue In the third quarter of 2013, the Company modified its Affinity Card Agreement (Agreement) with Bank of America Corporation (BAC), through which the Company sells miles and other items to BAC and the Company's loyalty program members accrue frequent flyer miles based on purchases using credit cards issued by BAC. As a result of the execution of the Agreement, consideration received as part of this agreement is subject to Accounting Standards Update 2009-13, "Multiple-Deliverable Revenue Arrangements - a consensus of the FASB Emerging Issues Task Force" (ASU 2009-13). The Company followed the rollforward transition approach of ASU 2009-13, which required that the Company's existing deferred revenue balance be adjusted to reflect the value, on a relative selling price basis, of any undelivered element remaining at the date of contract modification as if the Company had been applying ASU 2009-13 since inception of the Agreement. The relative selling price of the undelivered element (air transportation) is lower than the rate at which it had been deferred under the previous contract and the Company recorded a one-time, non-cash adjustment to decrease frequent flyer deferred revenue and increase Special mileage plan revenue. The amount recorded for the year ended December 31, 2013 was $192 million . Also during 2013, as part of the Company's ongoing evaluation of Mileage Plan program assumptions, the Company performed a statistical analysis of historical data, which refined its estimate of the amount of breakage in the mileage population. This new refinement enables the Company to better identify historical differences between certain of its mileage breakage estimates and the amounts that have actually been experienced. As a result, the Company increased its estimate of the number of frequent flyer miles expected to expire unused from 12% to 17.4% . Included in the Special mileage plan revenue item above is $44 million of additional revenue related to the effect of the change on the deferred revenue balance. Special Items In 2015, the Company recognized special items of $32 million in aggregate ( $20 million after tax, or $0.15 per diluted share). The special items are comprised of the recognition of an expense of $14 million due to lump sum settlements offered to terminated, vested participants in the qualified defined benefit pension plans, and a litigation-related matter. See Note 7. Employee Benefit Plans for more information regarding the pension settlement charge. Refer to Note 7. Employee Benefit Plans for detailed information about the $20 million benefit related to the curtailment of certain postretirement benefit plans recognized in 2014. Furthermore, in 2014, we recorded a one-time gain of $10 million associated with the settlement of a legal matter.

STOCK-BASED COMPENSATION PLANS

STOCK-BASED COMPENSATION PLANS	12 Months Ended
	Dec. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
STOCK-BASED COMPENSATION PLANS	NOTE 11. STOCK-BASED COMPENSATION PLANS The table below summarizes the components of total stock-based compensation (in millions): 2015 2014 2013 Stock options $ 2 $ 3 $ 3 Stock awards 11 10 10 Deferred stock awards 1 1 1 Employee stock purchase plan 3 2 2 Stock-based compensation $ 17 $ 16 $ 16 Tax benefit related to stock-based compensation $ 7 $ 6 $ 6 Unrecognized stock-based compensation for non-vested options and awards and the weighted-average period the expense will be recognized (in millions): Amount Weighted- Average Period Stock options $ 3 1.0 Stock awards 8 0.7 Unrecognized stock-based compensation $ 11 0.7 The Company has various equity incentive plans under which it may grant stock awards to directors, officers and employees. The Company also has an employee stock purchase plan (ESPP). The Company is authorized to issue 36 million shares of common stock under these plans, of which 16,353,597 shares remain available for future grants of either options or stock awards as of December 31, 2015 . Stock Options Stock options to purchase common stock are granted at the fair market value of the stock on the date of grant. The stock options granted have terms of up to ten years. The fair value of each option grant was estimated on the date of grant using the Black-Scholes option-pricing model with the following weighted-average assumptions used for grants: 2015 2014 2013 Expected volatility 53 % 65 % 67 % Expected term 6 years 6 years 6 years Risk-free interest rate 1.67 % 1.87 % 1.1 % Expected dividend yield 1.25 % 1.25 % — Weighted-average grant date fair value per share $ 28.71 $ 21.70 $ 14.74 Estimated fair value of options granted (millions) $ 3 $ 3 $ 3 The expected market price volatility is based on the historical volatility. The expected term is based on the estimated period of time until exercise based on historical experience. The risk-free interest rate is based on the U.S. Treasury yield curve in effect at the time of the grant. The expected dividend yield is based on the estimated weighted average dividend yield over the expected term. The expected forfeiture rates are based on historical experience. The tables below summarize stock option activity for the year ended December 31, 2015: Shares Weighted- Average Exercise Price Per Share Weighted- Average Contractual Life (Years) Aggregate Intrinsic Value (in millions) Outstanding, December 31, 2014 707,688 $ 21.57 6.4 $ 27 Granted 93,660 65.30 Exercised (255,717 ) 15.97 Canceled (1 ) 38.76 Forfeited or expired (5,285 ) 44.56 Outstanding, December 31, 2015 540,345 $ 31.58 6.3 $ 26 Exercisable, December 31, 2015 195,873 $ 18.62 5.6 $ 12 Vested or expected to vest, December 31, 2015 539,868 $ 31.57 6.3 $ 26 (in millions) 2015 2014 2013 Intrinsic value of option exercises $ 14 $ 20 $ 19 Cash received from stock option exercises 4 6 8 Tax benefit related to stock option exercises 5 7 7 Fair value of options vested 3 2 3 Stock Awards Restricted Stock Units (RSUs) are awarded to eligible employees and entitle the grantee to receive shares of common stock at the end of the vest period. The fair value of the RSUs is based on the stock price on the date of grant. The RSUs “cliff vest” after three years, or the period from the date of grant to the employee’s retirement eligibility, and expense is recognized accordingly. Performance Share Units (PSUs) are awarded to certain executives to receive shares of common stock if specific performance goals and market conditions are achieved. There are several tranches of PSUs which vest when performance goals and market conditions are met. The following table summarizes information about outstanding stock awards: Number of Units Weighted- Average Grant Date Fair Value Weighted- Average Contractual Life (Years) Aggregate Intrinsic Value (in millions) Non-vested, December 31, 2014 1,027,390 $ 26.19 0.6 $ 61 Granted 244,874 50.94 Vested (764,322 ) 26.33 Forfeited (37,227 ) 35.86 Non-vested, December 31, 2015 470,715 $ 38.09 0.8 $ 38 Deferred Stock Awards Deferred Stock Units (DSUs) are awarded to members of its Board of Directors as part of their retainers. The underlying common shares are issued upon retirement from the Board, but require no future service period. As a result, the entire intrinsic value of the awards is expensed on the date of grant. Employee Stock Purchase Plan (ESPP) The ESPP allows employees to purchase common stock at 85% of the stock price on the first day of the offering period or the specified purchase date, whichever is lower. Employees may contribute up to 10% of their base earnings during the offering period to purchase stock. Employees purchased 281,058 , 298,283 , and 171,227 shares in 2015 , 2014 , and 2013 under the ESPP.

OPERATING SEGMENT INFORMATION

OPERATING SEGMENT INFORMATION	12 Months Ended
	Dec. 31, 2015
Segment Reporting [Abstract]
Operating Segment Information	NOTE 12. OPERATING SEGMENT INFORMATION Air Group has two operating airlines - Alaska Airlines and Horizon Air. Each is a regulated airline with separate management teams. To manage the two operating airlines and the revenues and expenses associated with the CPAs, management views the business in three operating segments. Alaska Mainline - The Boeing 737 part of Alaska's business. Alaska Regional - Alaska's shorter distance network. In this segment, Alaska Regional records actual on board passenger revenue, less costs such as fuel, distribution costs, and payments made to Horizon, SkyWest and PenAir under CPAs. Additionally, Alaska Regional includes a small allocation of corporate overhead such as IT, finance and other administrative costs incurred by Alaska and on behalf of the regional operations. Horizon - Horizon operates regional aircraft. All of Horizon's capacity is sold to Alaska under a CPA. Expenses included those typically borne by regional airlines such as crew costs, ownership costs, and maintenance costs. Additionally, the following table reports “Air Group Adjusted,” which is not a measure determined in accordance with GAAP. The Company's chief operating decision-makers and others in management use this measure to evaluate operational performance and determine resource allocations. Adjustments are further explained below in reconciling to consolidated GAAP results. Operating segment information is as follows (in millions): Alaska Year Ended December 31, 2015 Mainline Regional Horizon Consolidating Air Group Adjusted (a) Special Items (b) Consolidated Operating revenues Passenger Mainline $ 3,939 $ — $ — $ — $ 3,939 $ — $ 3,939 Regional — 854 — — 854 — 854 Total passenger revenues 3,939 854 — — 4,793 — 4,793 CPA revenues — — 408 (408 ) — — — Freight and mail 103 5 — — 108 — 108 Other-net 621 72 4 — 697 — 697 Total operating revenues 4,663 931 412 (408 ) 5,598 — 5,598 Operating expenses Operating expenses, excluding fuel 2,653 695 375 (409 ) 3,314 32 3,346 Economic fuel 823 131 — — 954 — 954 Total operating expenses 3,476 826 375 (409 ) 4,268 32 4,300 Nonoperating income (expense) Interest income 19 — — 2 21 — 21 Interest expense (28 ) — (10 ) (4 ) (42 ) — (42 ) Other 28 — 1 6 35 — 35 19 — (9 ) 4 14 — 14 Income (loss) before income tax $ 1,206 $ 105 $ 28 $ 5 $ 1,344 $ (32 ) $ 1,312 Alaska Year Ended December 31, 2014 Mainline Regional Horizon Consolidating Air Group Adjusted (a) Special Items (b) Consolidated Operating revenues Passenger Mainline $ 3,774 $ — $ — $ — $ 3,774 $ — $ 3,774 Regional — 805 — — 805 — 805 Total passenger revenues 3,774 805 — — 4,579 — 4,579 CPA revenues — — 371 (371 ) — — — Freight and mail 109 5 — 114 — 114 Other-net 592 78 5 675 — 675 Total operating revenues 4,475 888 376 (371 ) 5,368 — 5,368 Operating expenses Operating expenses, excluding fuel 2,417 623 349 (371 ) 3,018 (30 ) 2,988 Economic fuel 1,251 190 — — 1,441 (23 ) 1,418 Total operating expenses 3,668 813 349 (371 ) 4,459 (53 ) 4,406 Nonoperating income (expense) Interest income 20 — — 1 21 — 21 Interest expense (32 ) — (12 ) (4 ) (48 ) — (48 ) Other 39 (1 ) 2 — 40 — 40 27 (1 ) (10 ) (3 ) 13 — 13 Income (loss) before income tax $ 834 $ 74 $ 17 $ (3 ) $ 922 $ 53 $ 975 Alaska Year Ended December 31, 2013 Mainline Regional Horizon Consolidating Air Group Adjusted (a) Special Items (b) Consolidated Operating revenues Passenger Mainline $ 3,490 $ — $ — $ — $ 3,490 $ — $ 3,490 Regional — 777 — — 777 — 777 Total passenger revenues 3,490 777 — — 4,267 — 4,267 CPA revenues — — 368 (368 ) — — — Freight and mail 109 4 — — 113 — 113 Other-net 513 66 5 — 584 192 776 Total operating revenues 4,112 847 373 (368 ) 4,964 192 5,156 Operating expenses Operating expenses, excluding fuel 2,293 585 341 (368 ) 2,851 — 2,851 Economic fuel 1,294 181 — — 1,475 (8 ) 1,467 Total operating expenses 3,587 766 341 (368 ) 4,326 (8 ) 4,318 Nonoperating income (expense) Interest income 18 — — — 18 — 18 Interest expense (38 ) — (14 ) (4 ) (56 ) — (56 ) Other 25 (12 ) 2 1 16 — 16 5 (12 ) (12 ) (3 ) (22 ) — (22 ) Income (loss) before income tax $ 530 $ 69 $ 20 $ (3 ) $ 616 $ 200 $ 816 (a) The 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. (b) Includes accounting adjustments related to mark-to-market fuel-hedge accounting charges (all years), pension settlement charge (2015), litigation-related matter (2015), non-cash curtailment gain (2014), a gain related to a legal matter (2014), and Special mileage plan revenue (2013). 2015 2014 2013 Depreciation: Alaska (a) $ 268 243 $ 223 Horizon 52 51 47 Parent company — — — Consolidated $ 320 $ 294 $ 270 Capital expenditures: Alaska (a) $ 821 $ 659 $ 494 Horizon 10 35 72 Consolidated $ 831 $ 694 $ 566 Total assets at end of period: Alaska (a) $ 8,129 $ 6,665 Horizon 718 809 Parent company 4,734 3,551 Elimination of inter-company accounts (7,048 ) (4,961 ) Consolidated $ 6,533 $ 6,064 (a) There are no depreciation expenses, capital expenditures or assets associated with purchased capacity flying at Alaska Regional.

GENERAL AND SUMMARY OF SIGNIF20

GENERAL AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	12 Months Ended
	Dec. 31, 2015
Accounting Policies [Abstract]
Organization and Basis of Accounting, Policy [Policy Text Block]	Organization and Basis of Presentation The consolidated financial statements include the accounts of Alaska Air Group, Inc. (Air Group or the Company) and its subsidiaries, Alaska Airlines, Inc. (Alaska) and Horizon Air Industries, Inc. (Horizon), through which the Company conducts substantially all of its operations. All significant intercompany balances and transactions have been eliminated. These financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America and their preparation requires the use of management’s estimates. Actual results may differ from these estimates.
Cash and Cash Equivalents, Policy [Policy Text Block]	Cash and Cash Equivalents 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 market value. The Company reduces cash balances when funds are disbursed. Due to the time delay in funds clearing the banks, the Company normally maintains a negative balance in its cash disbursement accounts, which is reported as a current liability. The amount of the negative cash balance was $12 million and $7 million at December 31, 2015 and 2014 , respectively, and is included in accounts payable, with the change in the balance during the year included in other financing activities in the consolidated statements of cash flows. The Company has restricted cash balances 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.
Marketable Securities, Available-for-sale Securities, Policy [Policy Text Block]	Marketable Securities Investments with original maturities of greater than three months and remaining maturities of less than one year are classified as short-term investments. Investments with maturities beyond one year may be classified as short-term based on their highly liquid nature and because such marketable securities represent the investment of cash that is available for current operations. All cash equivalents and short-term investments are classified as available-for-sale and realized gains and losses are recorded using the specific identification method. Changes in market value, excluding other-than-temporary impairments, are reflected in accumulated other comprehensive loss (AOCL). Investments are considered to be impaired when a decline in fair value is judged to be other-than-temporary. The Company uses a systematic methodology that considers available quantitative and qualitative evidence in evaluating potential impairment. If the cost of an investment exceeds its fair value, management evaluates, among other factors, general market conditions, credit quality of debt instrument issuers, the duration and extent to which the fair value is less than cost, our intent and ability to hold, or plans to sell, the investment. Once a decline in fair value is determined to be other-than-temporary, an impairment charge is recorded to Other-net in the consolidated statements of operations and a new cost basis in the investment is established.
Receivables, Policy [Policy Text Block]	Receivables Receivables are due on demand and consist primarily of airline traffic (including credit card) receivables, Mileage Plan™ partners, amounts due from other airlines related to interline agreements, government tax authorities, and other miscellaneous amounts due to the Company, and are net of an allowance for doubtful accounts. Management determines the allowance for doubtful accounts based on known troubled accounts and historical experience applied to an aging of accounts.
Inventory, Policy [Policy Text Block]	Inventories and Supplies—net Expendable aircraft parts, materials and supplies are stated at average cost and are included in inventories and supplies — net. An obsolescence allowance for expendable parts is accrued based on estimated lives of the corresponding fleet type and salvage values. The allowance for all non-surplus expendable inventories was $ 37 million and $34 million at December 31, 2015 and 2014 , respectively. Inventory and supplies — net also includes fuel inventory of $ 14 million and $21 million at December 31, 2015 and 2014 , respectively. Repairable and rotable aircraft parts inventories are included in flight equipment.
Property, Plant and Equipment, Policy [Policy Text Block]	Property, Equipment and Depreciation Property and equipment are recorded at cost and depreciated using the straight-line method over their estimated useful lives less an estimated salvage value, which are as follows: Aircraft and related flight equipment: Boeing 737 aircraft 20 years Bombardier Q400 15 years Buildings 25-30 years Minor building and land improvements 10 years Capitalized leases and leasehold improvements Shorter of lease term or estimated useful life Computer hardware and software 3-5 years Other furniture and equipment 5-10 years Salvage values used for aircraft are 10% of the fair value, but as aircraft near the end of their useful lives, we update the salvage value estimates based on current market conditions and expected use of the aircraft. “Related flight equipment” includes rotable and repairable spare inventories, which are depreciated over the associated fleet life unless otherwise noted. Capitalized interest is based on the Company’s weighted-average borrowing rate, is added to the cost of the related asset, and is depreciated over the estimated useful life of the asset. Maintenance and repairs, other than engine maintenance on some B737-700 and -900 engines, are expensed when incurred. Major modifications that extend the life or improve the usefulness of aircraft are capitalized and depreciated over their estimated period of use. Maintenance on some B737-700 and -900 engines is covered under power-by-the-hour agreements with third parties, whereby the Company pays a determinable amount, and transfers risk, to a third party. The Company expenses the contract amounts based on engine usage. The Company evaluates long-lived assets to be held and used for impairment whenever events or changes in circumstances indicate that the total carrying amount of an asset or asset group may not be recoverable. The Company groups assets for purposes of such reviews at the lowest level for which identifiable cash flows of the asset group are largely independent of the cash flows of other groups of assets and liabilities. An impairment loss is considered when estimated future undiscounted cash flows expected to result from the use of the asset or asset group and its eventual disposition are less than its carrying amount. If the asset or asset group is not considered recoverable, a write-down equal to the excess of the carrying amount over the fair value will be recorded.
Internal Use Software, Policy [Policy Text Block]	Internally Used Software Costs The Company capitalizes costs to develop internal-use software that are incurred in the application development stage. Amortization commences when the software is ready for its intended use and the amortization period is the estimated useful life of the software, generally three to five years. Capitalized costs primarily include contract labor and payroll costs of the individuals dedicated to the development of internal-use software.
Revenue Recognition, Deferred Revenue [Policy Text Block]	Deferred Revenue Deferred revenue results primarily from the sale of Mileage Plan™ miles to third-parties. This revenue is recognized when award transportation is provided or over the term of the applicable agreement.
Lease, Policy [Policy Text Block]	Operating Leases The Company leases aircraft, airport and terminal facilities, office space, and other equipment under operating leases. Some of these lease agreements contain rent escalation clauses or rent holidays. For scheduled rent escalation clauses during the lease terms or for rental payments commencing at a date other than the date of initial occupancy, the Company records minimum rental expenses on a straight-line basis over the terms of the leases in the consolidated statements of operations.
Leased Aircraft Return Costs [Policy Text Block]	Leased Aircraft Return Costs Cash payments associated with returning leased aircraft are accrued when it is probable that a cash payment will be made and that amount is reasonably estimable. Any accrual is based on the time remaining on the lease, planned aircraft usage and the provisions included in the lease agreement, although the actual amount due to any lessor upon return will not be known with certainty until lease termination. As leased aircraft are returned, any payments are charged against the established accrual. The accrual is part of other current and long-term liabilities, and was $5 million and $1 million as of December 31, 2015 and December 31, 2014 , respectively.
Revenue Recognition, Policy [Policy Text Block]	Revenue Recognition Passenger revenue is recognized when the passenger travels. Tickets sold but not yet used are reported as air traffic liability until travel or date of expiration. Air traffic liability includes approximately $42 million and $33 million related to credits for future travel, as of December 31, 2015 and December 31, 2014 , respectively. These credits are recognized into revenue either when the passenger travels or the date of expiration, which is twelve months from issuance. Commissions to travel agents and related fees are expensed when the related revenue is recognized. Passenger traffic commissions and related fees not yet recognized are included as a prepaid expense. 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. Due to complex pricing structures, refund and exchange policies, and interline agreements with other airlines, certain amounts are recognized as revenue using estimates regarding both the timing of the revenue recognition and the amount of revenue to be recognized. These estimates are based on the Company’s historical data. Freight and mail revenues are recognized when service is provided. Other - net revenues are primarily related to the Mileage Plan™ and they are recognized as described in the “Mileage Plan” paragraph below. Other - net also includes certain ancillary or non-ticket revenues, such as checked-bag fees, reservations fees, ticket change fees, on-board food and beverage sales, and to a much lesser extent commissions from car and hotel vendors, and from the sales of travel insurance. These items are recognized as revenue when the related services are provided. Airport lounge memberships are recognized as revenue over the membership period.
Frequent Flier Program, Policy [Policy Text Block]	Mileage Plan Alaska operates a frequent flier program (“Mileage Plan™”) that provides travel awards to members based on accumulated mileage. For miles earned by flying on Alaska or Horizon and through airline partners, the estimated cost of providing award travel is recognized as a selling expense and accrued as a liability as miles are earned and accumulated. Alaska also sells services, including miles for transportation, to non-airline partners, such as hotels, car rental agencies, and a major bank that offers Alaska Airlines affinity credit cards. The Company defers passenger revenue related to air transportation and certificates for discounted companion travel until the transportation is delivered. The deferred proceeds are recognized as passenger revenue for awards redeemed and flown on Alaska or Horizon, and as Other-net revenue for awards redeemed and flown on other airlines (less the cost paid to the other airlines based on contractual agreements). For the elements that represent use of the Alaska Airlines brand and access to frequent flier member lists and advertising, it is recognized as commission income in the period that those elements are sold and included in Other - net revenue in the consolidated statements of operations.
Advertising Cost, Policy, Expensed Advertising Cost [Policy Text Block]	Selling Expenses Selling expenses include credit card fees, global distribution systems charges, the estimated cost of Mileage Plan™ travel awards earned through air travel, advertising, promotional costs, commissions, and incentives. Advertising production costs are expensed the first time the advertising takes place.
Derivatives, Policy [Policy Text Block]	Derivative Financial Instruments The Company's operations are significantly impacted by changes in aircraft fuel prices and interest rates. In an effort to manage our exposure to these risks, the Company periodically enters into fuel and interest rate derivative instruments. These derivative instruments are recognized at fair value on the balance sheet and changes in the fair value is recognized in AOCL or in the consolidated statements of operations, depending on the nature of the instrument. The Company does not hold or issue derivative fuel hedge contracts for trading purposes and does not apply hedge accounting. For cash flow hedges related to our interest rate swaps, the effective portion of the derivative represents the change in fair value of the hedge that offsets the change in fair value of the hedged item. To the extent the change in the fair value of the hedge does not perfectly offset the change in the fair value of the hedged item, the ineffective portion of the hedge is immediately recognized in interest expense.
Fair Value of Financial Instruments, Policy [Policy Text Block]	Fair Value Measurements Accounting standards define fair value as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. The standards also establish a fair value hierarchy, which requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. There are three levels of inputs that may be used to measure fair value: Level 1 - Quoted prices in active markets for identical assets or liabilities. Level 2 - Observable inputs other than Level 1 prices such as quoted prices for similar assets or liabilities, quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3 - Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. The Company has elected not to use the Fair Value Option for non-financial instruments, and accordingly those assets and liabilities are carried at amortized cost. For financial instruments, those assets and liabilities are carried at fair value and are determined based on the market approach or income approach depending upon the level of inputs used.
Income Tax, Policy [Policy Text Block]	Income Taxes The Company uses the asset and liability approach for accounting and reporting income taxes. Deferred tax assets and liabilities are recognized for future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases, and for operating loss and tax credit carryforwards. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in the period that includes the enactment date. A valuation allowance would be established, if necessary, for the amount of any tax benefits that, based on available evidence, are not expected to be realized. The Company accounts for unrecognized tax benefits in accordance with the accounting standards.
Share-based Compensation, Option and Incentive Plans Policy [Policy Text Block]	Stock-Based Compensation Accounting standards require companies to recognize as expense the fair value of stock options and other equity-based compensation issued to employees as of the grant date. These standards apply to all stock awards that the Company grants to employees as well as the Company’s Employee Stock Purchase Plan (ESPP), which features a look-back provision and allows employees to purchase stock at a 15% discount. All stock-based compensation expense is recorded in wages and benefits in the consolidated statements of operations.
Earnings Per Share, Policy [Policy Text Block]	Earnings Per Share (EPS) Diluted EPS is calculated by dividing net income by the average common shares outstanding plus 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. In 2015 , 2014 , and 2013 , antidilutive stock options excluded from the calculation of EPS were not material.
New Accounting Pronouncements, Policy [Policy Text Block]	Recently Issued Accounting Pronouncements In May 2014, the FASB issued Accounting Standard Update 2014-09, "Revenue from Contracts with Customers" (ASU 2014-09), which requires an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers. The ASU will replace most existing revenue recognition guidance in U.S. GAAP when it becomes effective. The new standard is effective for the Company on January 1, 2018. The standard permits the use of either the retrospective or cumulative effect transition method. At this time, the Company believes the most significant impact to the financial statements will be in Mileage Plan revenues and liabilities. The Company currently uses the incremental cost approach for miles earned through travel. This standard eliminates that option and the Company will be required to increase its liability for earned miles through a relative selling price model. The Company has not evaluated the full impact of the standard, although application is expected to result in a material increase to Deferred Revenue. The Company has not yet selected a transition method.

GENERAL AND SUMMARY OF SIGNIF21

GENERAL AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)	12 Months Ended
	Dec. 31, 2015
Accounting Policies [Abstract]
Property, Plant and Equipment [Table Text Block]	Property and equipment are recorded at cost and depreciated using the straight-line method over their estimated useful lives less an estimated salvage value, which are as follows: Aircraft and related flight equipment: Boeing 737 aircraft 20 years Bombardier Q400 15 years Buildings 25-30 years Minor building and land improvements 10 years Capitalized leases and leasehold improvements Shorter of lease term or estimated useful life Computer hardware and software 3-5 years Other furniture and equipment 5-10 years Salvage values used for aircraft are 10% of the fair value, but as aircraft near the end of their useful lives, we update the salvage value estimates based on current market conditions and expected use of the aircraft. “Related flight equipment” includes rotable and repairable spare inventories, which are depreciated over the associated fleet life unless otherwise noted.
Liabilities from Mileage Plan [Table Text Block]	Alaska’s Mileage Plan™ deferred revenue and liabilities on the consolidated balance sheets (in millions): 2015 2014 Current Liabilities: Other accrued liabilities $ 368 $ 343 Other Liabilities and Credits: Deferred revenue 427 367 Other liabilities 19 20 Total $ 814 $ 730
Revenue from Mileage Plan [Table Text Block]	Alaska’s Mileage Plan™ revenue included in the consolidated statements of operations (in millions): 2015 2014 2013 Passenger revenues $ 267 $ 246 $ 208 Other-net revenues 329 295 256 Special mileage plan revenue (a) — — 192 Total Mileage Plan revenues $ 596 $ 541 $ 656

CASH, CASH EQUIVALENTS AND MA22

CASH, CASH EQUIVALENTS AND MARKETABLE SECURITIES (Tables)	12 Months Ended
	Dec. 31, 2015
Cash, Cash Equivalents, and Short-term Investments [Abstract]
Schedule of Cash, Cash Equivalents and Short-term Investments [Table Text Block]	Components for cash, cash equivalents and marketable securities (in millions): December 31, 2015 Cost Basis Unrealized Gains Unrealized Losses Fair Value Cash $ 4 $ — $ — $ 4 Cash equivalents 69 — — 69 Cash and cash equivalents 73 — — 73 U.S. government and agency securities 254 — (1 ) 253 Foreign government bonds 31 — — 31 Asset-backed securities 130 — — 130 Mortgage-backed securities 117 — (1 ) 116 Corporate notes and bonds 711 1 (4 ) 708 Municipal securities 17 — — 17 Marketable securities 1,260 1 (6 ) 1,255 Total $ 1,333 $ 1 $ (6 ) $ 1,328 December 31, 2014 Cost Basis Unrealized Gains Unrealized Losses Fair Value Cash $ 4 $ — $ — $ 4 Cash equivalents 103 — — 103 Cash and cash equivalents 107 — — 107 U.S. government and agency securities 166 — — 166 Foreign government bonds 25 — — 25 Asset-backed securities 130 — — 130 Mortgage-backed securities 127 — (1 ) 126 Corporate notes and bonds 644 3 (2 ) 645 Municipal securities 18 — — 18 Marketable securities 1,110 3 (3 ) 1,110 Total $ 1,217 $ 3 $ (3 ) $ 1,217
Schedule of Realized Gain (Loss) [Table Text Block]	Activity for marketable securities (in millions): 2015 2014 2013 Proceeds from sales and maturities $ 1,175 $ 1,092 $ 1,089 Gross realized gains 2 4 4 Gross realized losses (3 ) (2 ) (2 )
Schedule of Debt Investment Maturities [Table Text Block]	Maturities for marketable securities (in millions): December 31, 2015 Cost Basis Fair Value Due in one year or less $ 182 $ 182 Due after one year through five years 1,055 1,050 Due after five years through 10 years 14 14 Due after 10 years 9 9 Total $ 1,260 $ 1,255

DERIVATIVE INSTRUMENTS (Tables)

DERIVATIVE INSTRUMENTS (Tables)	12 Months Ended
	Dec. 31, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Derivative Instruments in Statement of Financial Position, Fair Value [Table Text Block]	Fair values of derivative instruments on the consolidated balance sheet (in millions): 2015 2014 Derivative Instruments Not Designated as Hedges Fuel hedge contracts Prepaid expenses and other current assets $ 2 $ 3 Other assets 2 4 Derivative Instruments Designated as Hedges Interest rate swaps Other accrued liabilities (5 ) (6 ) Other liabilities (13 ) (13 ) Losses in accumulated other comprehensive loss (AOCL) (18 ) (19 )
Schedule of Derivative Instruments, Gain (Loss) in Statement of Financial Performance [Table Text Block]	Pretax effect of derivative instruments on earnings and AOCL (in millions): 2015 2014 2013 Derivative Instruments Not Designated as Hedges Fuel hedge contracts Gains (losses) recognized in aircraft fuel expense $ (19 ) $ (18 ) $ (44 ) Derivative Instruments Designated as Hedges Interest rate swaps Gains (losses) recognized in aircraft rent (6 ) (6 ) (6 ) Gains (losses) recognized in other comprehensive income (OCI) (5 ) (8 ) 10

FAIR VALUE MEASUREMENTS (Tables

FAIR VALUE MEASUREMENTS (Tables)	12 Months Ended
	Dec. 31, 2015
Fair Value Disclosures [Abstract]
Fair Value, by Balance Sheet Grouping [Table Text Block]	Fair values of financial instruments on the consolidated balance sheet (in millions): December 31, 2015 Level 1 Level 2 Total Assets Marketable securities U.S. government and agency securities $ 253 $ — $ 253 Foreign government bonds — 31 31 Asset-backed securities — 130 130 Mortgage-backed securities — 116 116 Corporate notes and bonds — 708 708 Municipal securities — 17 17 Derivative instruments Fuel hedge contracts Call options — 4 4 Liabilities Derivative instruments Interest rate swap agreements — (18 ) (18 ) December 31, 2014 Level 1 Level 2 Total Assets Marketable securities U.S. government and agency securities $ 166 $ — $ 166 Foreign government bonds — 25 25 Asset-backed securities — 130 130 Mortgage-backed securities — 126 126 Corporate notes and bonds — 645 645 Municipal securities — 18 18 Derivative instruments Fuel hedge contracts Call options — 7 7 Liabilities Derivative instruments Interest rate swap agreements — (19 ) (19 ) Fixed-rate debt that is not carried at fair value on the consolidated balance sheet and the estimated fair value of long-term fixed-rate debt (in millions): 2015 2014 Carrying Amount $ 520 $ 614 Fair value 557 666

LONG-TERM DEBT (Tables)

LONG-TERM DEBT (Tables)	12 Months Ended
	Dec. 31, 2015
Debt Disclosure [Abstract]
Schedule of Long-term Debt Instruments [Table Text Block]	Long-term debt obligations (in millions): 2015 2014 Fixed-rate notes payable due through 2024 $ 520 $ 614 Variable-rate notes payable due through 2025 166 189 Long-term debt 686 803 Less current portion 115 117 $ 571 $ 686 Weighted-average fixed-interest rate 5.7 % 5.7 % Weighted-average variable-interest rate 1.8 % 1.6 %
Schedule of Maturities of Long-term Debt [Table Text Block]	Long-term debt principal payments for the next five years and thereafter (in millions): Total 2016 $ 115 2017 121 2018 151 2019 114 2020 116 Thereafter 69 Total principal payments $ 686

INCOME TAXES (Tables)

INCOME TAXES (Tables)	12 Months Ended
	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Schedule of Deferred Tax Assets and Liabilities [Table Text Block]	Deferred tax (assets) and liabilities comprise the following (in millions): 2015 2014 Excess of tax over book depreciation $ 1,110 $ 1,042 Other—net 23 22 Gross deferred tax liabilities 1,133 1,064 Mileage Plan (208 ) (206 ) Inventory obsolescence (22 ) (20 ) Deferred gains (8 ) (10 ) Employee benefits (167 ) (166 ) Fuel hedge contracts (5 ) (5 ) Other—net (41 ) (24 ) Gross deferred tax assets (451 ) (431 ) Net deferred tax liabilities $ 682 $ 633
Schedule of Components of Income Tax Expense (Benefit) [Table Text Block]	The components of income tax expense were as follows (in millions): 2015 2014 2013 Current tax expense: Federal $ 397 $ 229 $ 145 State 30 27 17 Total current 427 256 162 Deferred tax expense: Federal 60 103 131 State (23 ) 11 15 Total deferred 37 114 146 Income tax expense $ 464 $ 370 $ 308
Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]	Income tax expense reconciles to the amount computed by applying the U.S. federal rate of 35% to income before income tax and accounting change as follows (in millions): 2015 2014 2013 Income before income tax $ 1,312 $ 975 $ 816 Expected tax expense 459 341 286 Nondeductible expenses 4 4 4 State income taxes 19 25 21 State income sourcing (15 ) — — Other—net (3 ) — (3 ) Actual tax expense $ 464 $ 370 $ 308 Effective tax rate 35.4 % 37.9 % 37.7 %
Summary of Income Tax Contingencies [Table Text Block]	A summary of the Company's jurisdictions and the periods that are subject to examination are as follows: Jurisdiction Period Federal 2012 to 2014 Alaska 2012 to 2014 California 2010 to 2014 Oregon 2003 to 2014* *The 2003, 2004, 2008-2010 and 2011 Oregon tax returns are subject to examination only to the extent of net operating loss carryforwards from those years that were utilized in 2010 and later years. Changes in the liability for unrecognized tax benefits during 2015 , 2014 , and 2013 are as follows (in millions): 2015 2014 2013 Balance at January 1, $ 3 $ 2 $ 1 Additions based on tax positions and settlements related to the current year 19 1 1 Balance at December 31, $ 22 $ 3 $ 2

EMPLOYEE BENEFIT PLANS (Tables)

EMPLOYEE BENEFIT PLANS (Tables) - Qualified Defined Benefit [Member]	12 Months Ended
	Dec. 31, 2015
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Schedule of Assumptions Used [Table Text Block]	Weighted average assumptions used to determine benefit obligations: 2015 2014 Discount rates (a) 4.55% to 4.69% 4.20% Rate of compensation increases (a) 2.06% to 2.65% 2.85% to 3.91% (a) Varies by plan and related work group. Weighted average assumptions used to determine net periodic benefit cost: 2015 2014 2013 Discount rate 4.20% 4.85% 3.95% Expected return on plan assets 6.50% 6.75% 7.25% Rate of compensation increases (a) 2.85% to 3.91% 2.90% to 3.93% 3.05% to 4.02% (a) Varies by plan and related work group.
Schedule of Allocation of Plan Assets [Table Text Block]	The asset allocation of the funds in the qualified defined-benefit plans, by asset category, is as follows: 2015 2014 Asset category: Domestic equity securities 28 % 33 % Non-U.S. equity securities 12 % 14 % Fixed income securities 55 % 53 % Real estate 5 % — % Plan assets 100 % 100 % Plan asset by fund category (in millions): 2015 2014 Fair Value Hierarchy Fund type: U.S. equity market fund 491 634 (a) Non-U.S. equity fund 208 272 (a) Credit bond index fund 953 190 (a) Government/credit bond index fund — 821 (a) Plan assets in common commingled trusts $ 1,652 $ 1,917 Real estate 85 — Level 3 Total plan assets $ 1,737 $ 1,917 Target allocations for the primary asset classes based on current funded status are approximately: Domestic equities: 21% - 33% Non-U.S. equities: 7% - 17% Fixed income: 48% - 67% Real estate: 0% - 8%
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block]	Changes in our Level 3 plan assets for the year ended December 31, 2015 included: Asset Category December 31, 2014 Balance Net Realized and Unrealized Gains/Losses Net Purchases, Issuances and Settlements Net Transfers Into/(Out of) Level 3 December 31, 2015 Balance Real Estate $ — 5 80 — $ 85
Schedule of Net Funded Status [Table Text Block]	The following table sets forth the status of the qualified defined-benefit pension plans (in millions): 2015 2014 Projected benefit obligation (PBO) Beginning of year $ 2,050 $ 1,709 Service cost 41 33 Interest cost 84 81 Plan settlement (62 ) — Actuarial (gain) loss (140 ) 298 Benefits paid (75 ) (71 ) End of year $ 1,898 $ 2,050 Plan assets at fair value Beginning of year $ 1,917 $ 1,769 Actual return on plan assets (43 ) 219 Employer contributions — — Plan settlement (62 ) — Benefits paid (75 ) (71 ) End of year $ 1,737 $ 1,917 Funded status (unfunded) $ (161 ) $ (133 ) Percent funded 92 % 94 %
Schedule of Amounts Recognized in Balance Sheet [Table Text Block]	The amounts recognized in the consolidated balance sheets (in millions): 2015 2014 Accrued benefit liability-long term $ 173 $ 133 Plan assets-long term (within noncurrent Other Assets) (12 ) — Total liability recognized $ 161 $ 133 The amounts not yet reflected in net periodic benefit cost and included in AOCL: 2015 2014 Prior service credit $ (11 ) $ (12 ) Net loss 499 514 Amount recognized in AOCL (pretax) $ 488 $ 502
Schedule of Net Benefit Costs [Table Text Block]	Net pension expense for the qualified defined-benefit plans included the following components (in millions): 2015 2014 2013 Service cost $ 41 $ 33 $ 46 Interest cost 84 81 73 Expected return on assets (122 ) (117 ) (111 ) Amortization of prior service cost (1 ) (1 ) (1 ) Recognized actuarial loss 26 13 43 Settlement expense (special item) 14 — — Net pension expense $ 42 $ 9 $ 50
Schedule of Expected Benefit Payments [Table Text Block]	Future benefits expected to be paid over the next ten years under the qualified defined-benefit pension plans from the assets of those plans (in millions): 2016 $ 77 2017 86 2018 93 2019 96 2020 107 2021 - 2024 613

COMMITMENTS AND CONTINGENCIES C

COMMITMENTS AND CONTINGENCIES COMMITMENTS AND CONTINGENCIES (Tables)	12 Months Ended
	Dec. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Schedule of Future Minimum Rental Payments for Operating Leases and Unrecorded Unconditional Purchase Obligtaions [Table Text Block]	Future minimum fixed payments for commitments as of December 31, 2015 (in millions): Aircraft Leases Facility Leases Aircraft Commitments Capacity Purchase Agreements 2016 $ 113 $ 92 $ 505 $ 67 2017 104 88 549 58 2018 98 41 444 60 2019 90 41 390 64 2020 81 38 327 68 Thereafter 467 142 418 554 Total $ 953 $ 442 $ 2,633 $ 871

SHAREHOLDER'S EQUITY (Tables)

SHAREHOLDER'S EQUITY (Tables)	12 Months Ended
	Dec. 31, 2015
Equity [Abstract]
Schedule of Treasury Stock by Class [Table Text Block]	Share repurchase activity (in millions, except shares): 2015 2014 2013 Shares Amount Shares Amount Shares Amount 2015 $1 billion Repurchase Program 1,517,277 $ 120 — $ — — $ — 2014 $650 million Repurchase Program 5,691,051 $ 385 5,497,427 $ 265 — $ — 2012 $250 million Repurchase Program — — 1,819,304 83 4,984,186 159 Total 7,208,328 $ 505 7,316,731 $ 348 4,984,186 $ 159
Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block]	AOCL consisted of the following (in millions, net of tax): 2015 2014 Related to marketable securities (3 ) — Related to employee benefit plans (288 ) (298 ) Related to interest rate derivatives (12 ) (12 ) $ (303 ) $ (310 )

STOCK-BASED COMPENSATION PLANS

STOCK-BASED COMPENSATION PLANS (Tables)	12 Months Ended
	Dec. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of Compensation Cost for Share-based Payment Arrangements, Allocation of Share-based Compensation Costs by Plan [Table Text Block]	The table below summarizes the components of total stock-based compensation (in millions): 2015 2014 2013 Stock options $ 2 $ 3 $ 3 Stock awards 11 10 10 Deferred stock awards 1 1 1 Employee stock purchase plan 3 2 2 Stock-based compensation $ 17 $ 16 $ 16 Tax benefit related to stock-based compensation $ 7 $ 6 $ 6
Schedule of Unrecognized Compensation Cost, Nonvested Awards [Table Text Block]	Unrecognized stock-based compensation for non-vested options and awards and the weighted-average period the expense will be recognized (in millions): Amount Weighted- Average Period Stock options $ 3 1.0 Stock awards 8 0.7 Unrecognized stock-based compensation $ 11 0.7
Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]	The fair value of each option grant was estimated on the date of grant using the Black-Scholes option-pricing model with the following weighted-average assumptions used for grants: 2015 2014 2013 Expected volatility 53 % 65 % 67 % Expected term 6 years 6 years 6 years Risk-free interest rate 1.67 % 1.87 % 1.1 % Expected dividend yield 1.25 % 1.25 % — Weighted-average grant date fair value per share $ 28.71 $ 21.70 $ 14.74 Estimated fair value of options granted (millions) $ 3 $ 3 $ 3
Schedule of Share-based Compensation, Stock Options, Activity [Table Text Block]	The tables below summarize stock option activity for the year ended December 31, 2015: Shares Weighted- Average Exercise Price Per Share Weighted- Average Contractual Life (Years) Aggregate Intrinsic Value (in millions) Outstanding, December 31, 2014 707,688 $ 21.57 6.4 $ 27 Granted 93,660 65.30 Exercised (255,717 ) 15.97 Canceled (1 ) 38.76 Forfeited or expired (5,285 ) 44.56 Outstanding, December 31, 2015 540,345 $ 31.58 6.3 $ 26 Exercisable, December 31, 2015 195,873 $ 18.62 5.6 $ 12 Vested or expected to vest, December 31, 2015 539,868 $ 31.57 6.3 $ 26 (in millions) 2015 2014 2013 Intrinsic value of option exercises $ 14 $ 20 $ 19 Cash received from stock option exercises 4 6 8 Tax benefit related to stock option exercises 5 7 7 Fair value of options vested 3 2 3
Schedule of Share-based Compensation, Restricted Stock Units Award Activity [Table Text Block]	The following table summarizes information about outstanding stock awards: Number of Units Weighted- Average Grant Date Fair Value Weighted- Average Contractual Life (Years) Aggregate Intrinsic Value (in millions) Non-vested, December 31, 2014 1,027,390 $ 26.19 0.6 $ 61 Granted 244,874 50.94 Vested (764,322 ) 26.33 Forfeited (37,227 ) 35.86 Non-vested, December 31, 2015 470,715 $ 38.09 0.8 $ 38

OPERATING SEGMENT INFORMATION (

OPERATING SEGMENT INFORMATION (Tables)	12 Months Ended
	Dec. 31, 2015
Segment Reporting [Abstract]
Schedule of Segment Reporting Information, by Segment [Table Text Block]	Operating segment information is as follows (in millions): Alaska Year Ended December 31, 2015 Mainline Regional Horizon Consolidating Air Group Adjusted (a) Special Items (b) Consolidated Operating revenues Passenger Mainline $ 3,939 $ — $ — $ — $ 3,939 $ — $ 3,939 Regional — 854 — — 854 — 854 Total passenger revenues 3,939 854 — — 4,793 — 4,793 CPA revenues — — 408 (408 ) — — — Freight and mail 103 5 — — 108 — 108 Other-net 621 72 4 — 697 — 697 Total operating revenues 4,663 931 412 (408 ) 5,598 — 5,598 Operating expenses Operating expenses, excluding fuel 2,653 695 375 (409 ) 3,314 32 3,346 Economic fuel 823 131 — — 954 — 954 Total operating expenses 3,476 826 375 (409 ) 4,268 32 4,300 Nonoperating income (expense) Interest income 19 — — 2 21 — 21 Interest expense (28 ) — (10 ) (4 ) (42 ) — (42 ) Other 28 — 1 6 35 — 35 19 — (9 ) 4 14 — 14 Income (loss) before income tax $ 1,206 $ 105 $ 28 $ 5 $ 1,344 $ (32 ) $ 1,312 Alaska Year Ended December 31, 2014 Mainline Regional Horizon Consolidating Air Group Adjusted (a) Special Items (b) Consolidated Operating revenues Passenger Mainline $ 3,774 $ — $ — $ — $ 3,774 $ — $ 3,774 Regional — 805 — — 805 — 805 Total passenger revenues 3,774 805 — — 4,579 — 4,579 CPA revenues — — 371 (371 ) — — — Freight and mail 109 5 — 114 — 114 Other-net 592 78 5 675 — 675 Total operating revenues 4,475 888 376 (371 ) 5,368 — 5,368 Operating expenses Operating expenses, excluding fuel 2,417 623 349 (371 ) 3,018 (30 ) 2,988 Economic fuel 1,251 190 — — 1,441 (23 ) 1,418 Total operating expenses 3,668 813 349 (371 ) 4,459 (53 ) 4,406 Nonoperating income (expense) Interest income 20 — — 1 21 — 21 Interest expense (32 ) — (12 ) (4 ) (48 ) — (48 ) Other 39 (1 ) 2 — 40 — 40 27 (1 ) (10 ) (3 ) 13 — 13 Income (loss) before income tax $ 834 $ 74 $ 17 $ (3 ) $ 922 $ 53 $ 975 Alaska Year Ended December 31, 2013 Mainline Regional Horizon Consolidating Air Group Adjusted (a) Special Items (b) Consolidated Operating revenues Passenger Mainline $ 3,490 $ — $ — $ — $ 3,490 $ — $ 3,490 Regional — 777 — — 777 — 777 Total passenger revenues 3,490 777 — — 4,267 — 4,267 CPA revenues — — 368 (368 ) — — — Freight and mail 109 4 — — 113 — 113 Other-net 513 66 5 — 584 192 776 Total operating revenues 4,112 847 373 (368 ) 4,964 192 5,156 Operating expenses Operating expenses, excluding fuel 2,293 585 341 (368 ) 2,851 — 2,851 Economic fuel 1,294 181 — — 1,475 (8 ) 1,467 Total operating expenses 3,587 766 341 (368 ) 4,326 (8 ) 4,318 Nonoperating income (expense) Interest income 18 — — — 18 — 18 Interest expense (38 ) — (14 ) (4 ) (56 ) — (56 ) Other 25 (12 ) 2 1 16 — 16 5 (12 ) (12 ) (3 ) (22 ) — (22 ) Income (loss) before income tax $ 530 $ 69 $ 20 $ (3 ) $ 616 $ 200 $ 816 (a) The 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. (b) Includes accounting adjustments related to mark-to-market fuel-hedge accounting charges (all years), pension settlement charge (2015), litigation-related matter (2015), non-cash curtailment gain (2014), a gain related to a legal matter (2014), and Special mileage plan revenue (2013). 2015 2014 2013 Depreciation: Alaska (a) $ 268 243 $ 223 Horizon 52 51 47 Parent company — — — Consolidated $ 320 $ 294 $ 270 Capital expenditures: Alaska (a) $ 821 $ 659 $ 494 Horizon 10 35 72 Consolidated $ 831 $ 694 $ 566 Total assets at end of period: Alaska (a) $ 8,129 $ 6,665 Horizon 718 809 Parent company 4,734 3,551 Elimination of inter-company accounts (7,048 ) (4,961 ) Consolidated $ 6,533 $ 6,064 (a) There are no depreciation expenses, capital expenditures or assets associated with purchased capacity flying at Alaska Regional.

GENERAL AND SUMMARY OF SIGNIF32

GENERAL AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - CASH AND CASH EQUIVALENTS (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Accounting Policies [Abstract]
Negative cash balance	$ 12	$ 7

GENERAL AND SUMMARY OF SIGNIF33

GENERAL AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - INVENTORIES AND SUPPLIES - NET (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Accounting Policies [Abstract]
Allowance for all non-surplus expendable inventories	$ 37	$ 34
Fuel inventory	$ 14	$ 21

GENERAL AND SUMMARY OF SIGNIF34

GENERAL AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - PROPERTY, EQUIPMENT AND DEPRECIATION (Details)	12 Months Ended
	Dec. 31, 2015
Buildings [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	30 years
Buildings [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	25 years
Minor building and land improvements [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	10 years
Computer hardware and software [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	5 years
Computer hardware and software [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Other furniture and equipment [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	10 years
Other furniture and equipment [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	5 years
B737 | Aircraft [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	20 years
Q400 [Member] | Aircraft [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	15 years

GENERAL AND SUMMARY OF SIGNIF35

GENERAL AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - LEASED AIRCRAFT RETURN COSTS (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Accounting Policies [Abstract]
Leased aircraft return costs	$ 5	$ 1

GENERAL AND SUMMARY OF SIGNIF36

GENERAL AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - REVENUE RECOGNITION (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Accounting Policies [Abstract]
Travel credits for future travel	$ 42	$ 33

GENERAL AND SUMMARY OF SIGNIF37

GENERAL AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - MILEAGE PLAN (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Mileage Plan [Line Items]
Other accrued liabilities	$ 661	$ 585
Other liabilities	362	327
Deferred revenue	431	374
Deferred revenue from Mileage Plan awards issued but not yet flown	37	33
Passenger revenues	4,793	4,579	$ 4,267
Other-net revenues	697	675	584
Special Revenue	0	0	192
Total Operating Revenues	5,598	5,368	5,156
Revenue From Mileage Plan [Member]
Mileage Plan [Line Items]
Passenger revenues	267	246	208
Other-net revenues	329	295	256
Special Revenue	0	0	192
Total Operating Revenues	596	541	656
Commission revenue	280	261	$ 213
Liabilities From Mileage Plan [Member]
Mileage Plan [Line Items]
Other accrued liabilities	368	343
Other liabilities	19	20
Deferred revenue	427	367
Liabilities	$ 814	$ 730

GENERAL AND SUMMARY OF SIGNIF38

GENERAL AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - SELLING EXPENSES (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Accounting Policies [Abstract]
Advertising expense	$ 55	$ 49	$ 28

GENERAL AND SUMMARY OF SIGNIF39

GENERAL AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES GENERAL AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - STOCK-BASED COMPENSATION (Details)	12 Months Ended
	Dec. 31, 2015
Employee stock purchase plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Discount from Market Price, Purchase Date	15.00%

GENERAL AND SUMMARY OF SIGNIF40

GENERAL AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - RECENTLY ISSUED ACCOUNTING PRONOUNCEMENTS (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
New Accounting Pronouncement, Early Adoption [Line Items]
Total Current Assets	$ 1,663	$ 1,639
Other liabilities	$ 362	327
New Accounting Pronouncement, Early Adoption, Effect [Member]
New Accounting Pronouncement, Early Adoption [Line Items]
Total Current Assets		(117)
Other liabilities		$ (117)

CASH, CASH EQUIVALENTS AND MA41

CASH, CASH EQUIVALENTS AND MARKETABLE SECURITIES (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Cash and Cash Equivalents [Abstract]
Cash	$ 4	$ 4
Money Market Funds, at Carrying Value	69	103
Cash equivalents	69	103
Cash and cash equivalents	73	107	$ 80	$ 122
Available-for-sale Securities, Current [Abstract]
Marketable securities, Cost Basis	1,260	1,110
Marketable securities, Unrealized Gains	1	3
Marketable securities, Unrealized Losses	(6)	(3)
Marketable securities, Fair Value	1,255	1,110
Cash and marketables securities, Cost Basis	1,333	1,217
Total cash and marketable securities	1,328	1,217
Available-for-sale Securities, Activity [Abstract]
Proceeds from sales and maturities	1,175	1,092	1,089
Gross realized gains	2	4	4
Gross realized losses	(3)	(2)	$ (2)
U.S. government and agency securities
Available-for-sale Securities, Current [Abstract]
Marketable securities, Cost Basis	254	166
Marketable securities, Unrealized Gains	0	0
Marketable securities, Unrealized Losses	(1)	0
Marketable securities, Fair Value	253	166
Foreign government bonds
Available-for-sale Securities, Current [Abstract]
Marketable securities, Cost Basis	31	25
Marketable securities, Unrealized Gains	0	0
Marketable securities, Unrealized Losses	0	0
Marketable securities, Fair Value	31	25
Asset-backed securities
Available-for-sale Securities, Current [Abstract]
Marketable securities, Cost Basis	130	130
Marketable securities, Unrealized Gains	0	0
Marketable securities, Unrealized Losses	0	0
Marketable securities, Fair Value	130	130
Mortgage-backed securities
Available-for-sale Securities, Current [Abstract]
Marketable securities, Cost Basis	117	127
Marketable securities, Unrealized Gains	0	0
Marketable securities, Unrealized Losses	(1)	(1)
Marketable securities, Fair Value	116	126
Corporate notes and bonds
Available-for-sale Securities, Current [Abstract]
Marketable securities, Cost Basis	711	644
Marketable securities, Unrealized Gains	1	3
Marketable securities, Unrealized Losses	(4)	(2)
Marketable securities, Fair Value	708	645
Municipal securities
Available-for-sale Securities, Current [Abstract]
Marketable securities, Cost Basis	17	18
Marketable securities, Unrealized Gains	0	0
Marketable securities, Unrealized Losses	0	0
Marketable securities, Fair Value	$ 17	$ 18

CASH, CASH EQUIVALENTS AND MA42

CASH, CASH EQUIVALENTS AND MARKETABLE SECURITIES - MATURITIES (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Cost Basis [Abstract]
Due in one year or less	$ 182
Due after one year through five years	1,055
Due after five years through 10 years	14
Due after 10 years	9
Marketable securities, Cost Basis	1,260	$ 1,110
Fair Value [Abstract]
Due in one year or less	182
Due after one year through five years	1,050
Due after five years through 10 years	14
Due after 10 years	9
Marketable securities, Fair Value	$ 1,255	$ 1,110

DERIVATIVE INSTRUMENTS - BALANC

DERIVATIVE INSTRUMENTS - BALANCE SHEET CLASSIFICATION (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Derivatives, Fair Value [Line Items]
Accumulated other comprehensive loss	$ (303)	$ (310)
Fuel hedge contracts [Member] | Derivative Instruments Not Designated as Hedges [Member] | Fuel Hedge Contracts, Current [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets, Current	2	3
Fuel hedge contracts [Member] | Derivative Instruments Not Designated as Hedges [Member] | Fuel Hedge Contracts, Noncurrent [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets, Noncurrent	2	4
Interest rate swaps agreements [Member] | Derivative Instruments Designated as Hedges [Member] | Other Accrued Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Liabilities, Current	(5)	(6)
Interest rate swaps agreements [Member] | Derivative Instruments Designated as Hedges [Member] | Other Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Liabilities, Noncurrent	(13)	(13)
Interest rate swaps agreements [Member] | Derivative Instruments Designated as Hedges [Member] | Accumulated Other Comprehensive Loss [Member]
Derivatives, Fair Value [Line Items]
Accumulated other comprehensive loss	$ 18	$ 19

DERIVATIVE INSTRUMENTS - INCOME

DERIVATIVE INSTRUMENTS - INCOME STATEMENT (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Loss in Accumulated Other Comprehensive Loss To Be Reclassified Within Next Twelve Months	$ 5
Derivative Instruments Not Designated as Hedges [Member] | Fuel hedge contracts [Member] | Gains (losses) recognized in aircraft fuel expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Losses recognized in income	(19)	$ (18)	$ (44)
Cash Flow Hedging [Member] | Derivative Instruments Designated as Hedges [Member] | Interest rate swaps agreements [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Losses in accumulated other comprehensive loss	(5)	(8)	10
Cash Flow Hedging [Member] | Derivative Instruments Designated as Hedges [Member] | Interest rate swaps agreements [Member] | Gains (losses) recognized in aircraft rent [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Losses recognized in income	$ (6)	$ (6)	$ (6)

DERIVATIVE INSTRUMENTS - FAIR V

DERIVATIVE INSTRUMENTS - FAIR VALUE OF HEDGE POSITIONS (Details) gallons in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2015USD ($)gallonsaircraft	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)
Derivative [Line Items]
Net cash received (paid) to for new positions and settlements | $	$ (17)	$ (9)	$ 5
B737-800 [Member]
Derivative [Line Items]
Capital Leased Assets, Number of B737-800 Aircraft | aircraft	6
Not Designated as Hedging Instrument [Member] | Fuel hedge contracts [Member]
Derivative [Line Items]
Fuel hedge contracts outstanding (in gallons) | gallons	273

FAIR VALUE MEASUREMENTS - FAIR

FAIR VALUE MEASUREMENTS - FAIR VALUE OF ASSETS AND LIABILITIES (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Current	$ 1,255	$ 1,110
Fuel hedge contracts [Member] | Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative instruments, assets	4	7
Fuel hedge contracts [Member] | Level 1 [Member] | Recurring [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] | Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative instruments, assets	4	7
Interest rate swaps agreements [Member] | Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative instruments, liabilities	(18)	(19)
Interest rate swaps agreements [Member] | Level 1 [Member] | Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative instruments, liabilities	0	0
Interest rate swaps agreements [Member] | Level 2 [Member] | Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative instruments, liabilities	(18)	(19)
U.S. government and agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Current	253	166
U.S. government and agency securities | Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	253	166
U.S. government and agency securities | Level 1 [Member] | Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Current	253
Marketable securities		166
U.S. government and agency securities | Level 2 [Member] | Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0	0
Foreign government bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Current	31	25
Foreign government bonds | Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	31	25
Foreign government bonds | Level 1 [Member] | Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0	0
Foreign government bonds | Level 2 [Member] | Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	31	25
Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Current	130	130
Asset-backed securities | Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	130	130
Asset-backed securities | Level 1 [Member] | Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0	0
Asset-backed securities | Level 2 [Member] | Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	130	130
Mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Current	116	126
Mortgage-backed securities | Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	116	126
Mortgage-backed securities | Level 1 [Member] | Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0	0
Mortgage-backed securities | Level 2 [Member] | Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	116	126
Corporate notes and bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Current	708	645
Corporate notes and bonds | Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	708	645
Corporate notes and bonds | Level 1 [Member] | Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0	0
Corporate notes and bonds | Level 2 [Member] | Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	708	645
Municipal securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Current	17	18
Municipal securities | Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	17	18
Municipal securities | Level 1 [Member] | Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0	0
Municipal securities | Level 2 [Member] | Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	$ 17	$ 18

FAIR VALUE MEASUREMENTS - LONG-

FAIR VALUE MEASUREMENTS - LONG-TERM DEBT (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Carrying Amount [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	$ 520	$ 614
Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	$ 557	$ 666

LONG-TERM DEBT - SCHEDULE OF LO

LONG-TERM DEBT - SCHEDULE OF LONG-TERM DEBT (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Debt Instrument [Line Items]
Long-term Debt	$ 686	$ 803
Less current portion	115	117
Long-term debt, net of current portion	$ 571	$ 686
Weighted-average variable-interest rate	5.70%	5.70%
Weighted-average variable-interest rate	1.80%	1.60%
Proceeds from issuance of long-term debt	$ 0	$ 51	$ 0
Long-term debt payments	116	119	$ 161
Long-term Debt, Fiscal Year Maturity [Abstract]
2,016	115
2,017	121
2,018	151
2,019	114
2,020	116
Thereafter	69
Long-term Debt	686	803
Fixed-rate notes payable due through 2024
Debt Instrument [Line Items]
Long-term Debt	520	614
Long-term Debt, Fiscal Year Maturity [Abstract]
Long-term Debt	520	614
Variable-rate notes payable due through 2025
Debt Instrument [Line Items]
Long-term Debt	166	189
Long-term Debt, Fiscal Year Maturity [Abstract]
Long-term Debt	$ 166	$ 189

LONG-TERM DEBT - LINE OF CREDIT

LONG-TERM DEBT - LINE OF CREDIT (Details)	12 Months Ended
	Dec. 31, 2015USD ($)aircraftcredit_facility
Line of Credit Facility [Line Items]
Number of credit facilities | credit_facility	3
Line of Credit Facility, minimum asset requirement	$ 500,000,000
Credit Facility 1 [Member] | Secured by aircraft [Member]
Line of Credit Facility [Line Items]
Line of credit facility, borrowing capacity	100,000,000
Credit Facility 2 [Member] | Secured by other [Member]
Line of Credit Facility [Line Items]
Line of credit facility, borrowing capacity	100,000,000
Credit Facility 3 [Member]
Line of Credit Facility [Line Items]
Line of credit facility, borrowing capacity	$ 52,000,000
Number of aircrafts used as collateral | aircraft	2
Secured Debt [Member] | Credit Facility 1 [Member]
Line of Credit Facility [Line Items]
Line of credit facility, borrowing capacity	$ 100,000,000
Secured Debt [Member] | Credit Facility 2 [Member]
Line of Credit Facility [Line Items]
Line of credit facility, borrowing capacity	$ 100,000,000

INCOME TAXES - DEFERRED TAX ASS

INCOME TAXES - DEFERRED TAX ASSETS AND LIABILITIES (Details) - USD ($)	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Excess of tax over book depreciation	$ 1,110,000,000	$ 1,042,000,000
Other—net	23,000,000	22,000,000
Gross deferred tax liabilities	1,133,000,000	1,064,000,000
Mileage Plan	(208,000,000)	(206,000,000)
Inventory obsolescence	(22,000,000)	(20,000,000)
Deferred gains	(8,000,000)	(10,000,000)
Employee benefits	(167,000,000)	(166,000,000)
Fuel hedge contracts	(5,000,000)	(5,000,000)
Other—net	(41,000,000)	(24,000,000)
Gross deferred tax assets	451,000,000	431,000,000
Net deferred tax liabilities	682,000,000	$ 633,000,000
Deferred tax assets valuation allowance	$ 0

INCOME TAXES - COMPONENTS OF TA

INCOME TAXES - COMPONENTS OF TAX EXPENSE (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Current tax expense (benefit):
Federal	$ 397	$ 229	$ 145
State	30	27	17
Total current	427	256	162
Deferred tax expense:
Federal	60	103	131
State	(23)	11	15
Total deferred	37	114	146
Total tax expense related to income	$ 464	$ 370	$ 308

INCOME TAXES - EFFECTIVE INCOME

INCOME TAXES - EFFECTIVE INCOME TAX RECONCILIATION (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
U.S. federal tax rate		35.00%	35.00%	35.00%
Income before income tax			$ 975	$ 816
Income (loss) before income tax		$ 1,312	975	816
Expected tax expense		459	341	286
Nondeductible expenses		4	4	4
State income taxes		19	25	21
State income sourcing		(15)	0	0
Other—net		(3)	0	(3)
Total tax expense related to income		$ 464	$ 370	$ 308
Effective tax rate		35.40%	37.90%	37.70%
Tax amendment, cumulative benefit	$ 26
Additions based on tax positions and settlements related to the current year	$ 18	$ 19	$ 1	$ 1

INCOME TAXES INCOME TAXES - UNC

INCOME TAXES INCOME TAXES - UNCERTAIN TAX POSITIONS (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
Beginning balance		$ 3	$ 2	$ 1
Additions based on tax positions and settlements related to the current year	$ 18	19	1	1
Ending balance	$ 22	$ 22	$ 3	$ 2

EMPLOYEE BENEFIT PLANS EMPLOYEE

EMPLOYEE BENEFIT PLANS EMPLOYEE BENEFIT PLANS - ADDITIONAL INFORMATION (Details)	12 Months Ended
	Dec. 31, 2015plan
Compensation and Retirement Disclosure [Abstract]
Number of defined benefit plans	4
Number of defined contribution plans	5

EMPLOYEE BENEFIT PLANS - ASSUMP

EMPLOYEE BENEFIT PLANS - ASSUMPTIONS (Details) - Qualified Defined Benefit [Member]	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation [Abstract]
Benefit obligations, Weighted-average discount rate		4.20%
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Net period benefit costs, Weighted-average discount rate	4.20%	4.85%	3.95%
Net period benefit costs, Weighted-average expected return on assets	6.50%	6.75%	7.25%
Minimum [Member]
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation [Abstract]
Benefit obligations, Weighted-average discount rate	4.55%
Benefit obligations, Rate of compensation increase	2.06%	2.85%
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Net period benefit costs, Rate of compensation increase	2.85%	2.90%	3.05%
Maximum [Member]
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation [Abstract]
Benefit obligations, Weighted-average discount rate	4.69%
Benefit obligations, Rate of compensation increase	2.65%	3.91%
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Net period benefit costs, Rate of compensation increase	3.91%	3.93%	4.02%

EMPLOYEE BENEFIT PLANS - PLAN A

EMPLOYEE BENEFIT PLANS - PLAN ASSETS (Details) - Qualified Defined Benefit [Member] - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Plan asset allocations	100.00%	100.00%
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Plan Assets	$ 1,737,000,000	$ 1,917,000,000	$ 1,769,000,000
Level 2 [Member]
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Plan Assets	$ 1,652,000,000	$ 1,917,000,000
Equity funds [Member] | U.S.
Defined Benefit Plan Disclosure [Line Items]
Plan asset allocations	28.00%	33.00%
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Equities, Range Minimum	21.00%
Equities, Range Maximum	33.00%
Equity funds [Member] | U.S. | Level 2 [Member]
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Plan Assets	$ 491,000,000	$ 634,000,000
Equity funds [Member] | Non-U.S. [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan asset allocations	12.00%	14.00%
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Equities, Range Minimum	7.00%
Equities, Range Maximum	17.00%
Equity funds [Member] | Non-U.S. [Member] | Level 2 [Member]
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Plan Assets	$ 208,000,000	$ 272,000,000
Credit bond index fund [Member] | Level 2 [Member]
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Plan Assets	$ 953,000,000	$ 190,000,000
Fixed Income Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan asset allocations	55.00%	53.00%
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Equities, Range Minimum	48.00%
Equities, Range Maximum	67.00%
Government and credit bond index funds [Member] | Level 2 [Member]
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Plan Assets	$ 0	$ 821,000,000
Real Estate [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan asset allocations	5.00%	0.00%
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Equities, Range Minimum	0.00%
Equities, Range Maximum	8.00%
Real Estate [Member] | Level 3 [Member]
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Plan Assets	$ 85,000,000	$ 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings and Other Comprehensive Income (Loss)	5
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases, (Sales), Issuances, (Settlements)	80
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers, Net	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	$ 85,000,000

EMPLOYEE BENEFIT PLANS - FUNDED

EMPLOYEE BENEFIT PLANS - FUNDED STATUS (Details) - Qualified Defined Benefit [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Benefit obligation
Beginning of year	$ 2,050	$ 1,709
Service cost	41	33	$ 46
Interest cost	84	81	73
Plan settlement	(62)	0
Actuarial (gain) loss	(140)	298
Benefits paid	(75)	(71)
End of year	1,898	2,050	1,709
Plan assets at fair value
Beginning of year	1,917	1,769
Actual return on plan assets	(43)	219
Employer contributions	0	0
Plan settlement	(62)	0
Benefits paid	(75)	(71)
End of year	1,737	1,917	$ 1,769
Funded status (unfunded)	$ (161)	$ (133)
Percent funded	92.00%	94.00%
Accumulated benefit obligation	$ 1,753	$ 1,909

EMPLOYEE BENEFIT PLANS - AMOUNT

EMPLOYEE BENEFIT PLANS - AMOUNTS RECOGNIZED IN CONSOLIDATED BALANCE SHEETS (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Pension and Other Postretirement Defined Benefit Plans, Liabilities [Abstract]
Accrued benefit liability-long term	$ 270	$ 246
Qualified Defined Benefit [Member]
Pension and Other Postretirement Defined Benefit Plans, Liabilities [Abstract]
Accrued benefit liability-long term	173	133
Plan assets-long term (within noncurrent Other Assets)	(12)	0
Total liability recognized	161	133
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), before Tax [Abstract]
Prior service cost (credit)	(11)	(12)
Net gain	499	514
Amount recognized in AOCI (pretax)	$ 488	$ 502

EMPLOYEE BENEFIT PLANS - EXPECT

EMPLOYEE BENEFIT PLANS - EXPECTED AMORTIZATION FROM AOCI (Details) - Qualified Defined Benefit [Member] $ in Millions	12 Months Ended
	Dec. 31, 2015USD ($)
Defined Benefit Plan Disclosure [Line Items]
Prior service credit	$ (1)
Net loss	$ 25

EMPLOYEE BENEFIT PLANS - NET PE

EMPLOYEE BENEFIT PLANS - NET PENSION EXPENSE (Details) - Qualified Defined Benefit [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	$ 41	$ 33	$ 46
Interest cost	84	81	73
Expected return on assets	(122)	(117)	(111)
Amortization of prior service cost	(1)	(1)	(1)
Recognized actuarial loss	26	13	43
Settlement expense (special item)	(14)	0	0
Net periodic benefit cost	42	9	$ 50
Plan settlement	$ 62	$ 0

EMPLOYEE BENEFIT PLANS - FUTURE

EMPLOYEE BENEFIT PLANS - FUTURE BENEFITS EXPECTED TO BE PAID (Details) - Qualified Defined Benefit [Member] $ in Millions	Dec. 31, 2015USD ($)
Defined Benefit Plan Disclosure [Line Items]
2,016	$ 77
2,017	86
2,018	93
2,019	96
2,020	107
2021 - 2024	$ 613

EMPLOYEE BENEFIT PLANS EMPLOY62

EMPLOYEE BENEFIT PLANS EMPLOYEE BENEFIT PLANS - POSTRETIREMENT MEDICAL BENEFITS (Details) - Postretirement Medical Benefits [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Benefit obligation	$ 64	$ 81
Recognized net gain (loss) due to curtailments	25
Recognized net gain (loss) due to curtailments, sick leave subsidy	5
Recognized net gain (loss) due to curtailments, special items	$ 20

EMPLOYEE BENEFIT PLANS - DEFINE

EMPLOYEE BENEFIT PLANS - DEFINED CONTRIBUTION PLANS (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Compensation and Retirement Disclosure [Abstract]
Total expense for the defined-contribution plans	$ 60	$ 54	$ 44

EMPLOYEE BENEFIT PLANS - PILOT

EMPLOYEE BENEFIT PLANS - PILOT LONG-TERM DISABILITY BENEFITS (Details) - Postretirement Health Coverage [Member] - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Total liability net of a prefunded trust account	$ 19	$ 16
Prefunded trust account	$ 2	$ 2

EMPLOYEE BENEFIT PLANS - EMPLOY

EMPLOYEE BENEFIT PLANS - EMPLOYEE INCENTIVE-PAY PLANS (Details) $ in Millions	12 Months Ended
	Dec. 31, 2015USD ($)$ / Quarter	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)
Defined Benefit Plan Disclosure [Line Items]
Variable incentive pay | $	$ 120	$ 116	$ 105
Operational Performance Rewards Program entitles all Air Group employees to maximum quarterly payouts (in dollars per quarter) | $ / Quarter	300

COMMITMENTS AND CONTINGENCIES66

COMMITMENTS AND CONTINGENCIES COMMITMENTS AND CONTINGENCIES (Details) $ in Millions	12 Months Ended
	Dec. 31, 2015USD ($)aircraftcarriers	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)	Dec. 31, 2017aircraft
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Rent expense	$ 295	$ 288	$ 290
Capacity purchase arrangements, Carriers | carriers	3
Horizon [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Capacity purchase arrangements, Percent	100.00%
Aircraft Commitments [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
2,016	$ 505
2,017	549
2,018	444
2,019	390
2,020	327
Thereafter	418
Total	2,633
Capacity Purchase Agreements[Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
2,016	67
2,017	58
2,018	60
2,019	64
2,020	68
Thereafter	554
Total	871
Aircraft Leases [Member]
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2,016	113
2,017	104
2,018	98
2,019	90
2,020	81
Thereafter	467
Total	953
Facility Leases [Member]
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2,016	92
2,017	88
2,018	41
2,019	41
2,020	38
Thereafter	142
Total	$ 442
B-737 [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Commited to purchase (in aircraft) | aircraft	68
Option to purchase additional (in aircraft) | aircraft	46
B737-900ER [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Commited to purchase (in aircraft) | aircraft	31
B737 MAX [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Commited to purchase (in aircraft) | aircraft	37
Q400 [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Commited to purchase (in aircraft) | aircraft	2
Option to purchase additional (in aircraft) | aircraft	5
CRJ-700 [Member] | Aircraft Leases [Member] | Airline Capacity Purchase Arrangements [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Number of Aircraft under New Capacity Purchase Agreement | aircraft	2
Property Subject to Operating Lease [Member] | B-737 [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Operating leases, number of leased assets (in aircraft) | aircraft	27
Property Subject to Operating Lease [Member] | Q400 [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Operating leases, number of leased assets (in aircraft) | aircraft	15
Property Subject to Operating Lease [Member] | E-175 [Domain]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Operating leases, number of leased assets (in aircraft) | aircraft	5
Property Subject to Operating Lease [Member] | CRJ-700 [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Operating leases, number of leased assets (in aircraft) | aircraft	8
Property Subject to Operating Lease [Member] | CRJ-700 [Member] | Aircraft Leases [Member] | Airline Capacity Purchase Arrangements [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Number of Aircraft under New Capacity Purchase Agreement | aircraft	6
Operating Aircraft [Member] | CRJ-700 [Member] | Aircraft Leases [Member] | Airline Capacity Purchase Arrangements [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Number of Aircraft under New Capacity Purchase Agreement | aircraft	8
Operating Aircraft [Member] | Original E175 [Member] | Aircraft Leases [Member] | Airline Capacity Purchase Arrangements [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Number of Aircraft under New Capacity Purchase Agreement | aircraft	8
SkyWest [Member] | Property Subject to Operating Lease [Member] | E-175 [Domain]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Operating leases, number of leased assets (in aircraft) | aircraft	15
SkyWest [Member] | Property Subject to Operating Lease [Member] | CRJ-700 [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Operating leases, number of leased assets (in aircraft) | aircraft	6
SkyWest [Member] | Property Available for Operating Lease [Member] | E-175 [Domain] | Aircraft Leases [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Operating Leases, Number of Additional Units That Could Be Leased | aircraft	8
Scenario, Forecast [Member] | Property Subject to Operating Lease [Member] | E-175 [Domain]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Operating leases, number of leased assets (in aircraft) | aircraft				8

SHAREHOLDER'S EQUITY SHAREHOLDE

SHAREHOLDER'S EQUITY SHAREHOLDERS' EQUITY - STOCK CHANGES (Details) - $ / shares	Dec. 31, 2015	Dec. 31, 2014
Stock Split [Line Items]
Common stock, shares authorized	200,000,000	200,000,000
Common stock, par value	$ 0.01	$ 0.01
prestocksplit [Domain]
Stock Split [Line Items]
Common stock, shares authorized	100,000,000
Common stock, par value	$ 1

SHAREHOLDER'S EQUITY SHAREHOL68

SHAREHOLDER'S EQUITY SHAREHOLDERS' EQUITY - DIVIDENDS (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended	3 Months Ended	12 Months Ended
	Feb. 11, 2016	Sep. 30, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Subsequent Event [Line Items]
Common Stock, Dividends, Per Share, Declared		$ 0.20	$ 0.80	$ 0.50	$ 0.20
Payments of Dividends			$ 102	$ 68	$ 28
Subsequent Event [Member]
Subsequent Event [Line Items]
Common Stock, Dividends, Per Share, Declared	$ 0.275
DividendIncrease	38.00%

SHAREHOLDER'S EQUITY - COMMON S

SHAREHOLDER'S EQUITY - COMMON STOCK REPURCHASE (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Aug. 31, 2015	May. 01, 2014	Sep. 01, 2012
Equity, Class of Treasury Stock [Line Items]
Common stock repurchase (in shares)	7,208,328	7,316,731	4,984,186
Common stock repurchase	$ 505	$ 348	$ 159
2015 $1 billion Repurchase Program [Member]
Equity, Class of Treasury Stock [Line Items]
Share repurchase program, authorized amount				$ 1,000
Common stock repurchase (in shares)	1,517,277
Common stock repurchase	$ 120
2014 $650 million Repurchase Program
Equity, Class of Treasury Stock [Line Items]
Share repurchase program, authorized amount					$ 650
Common stock repurchase (in shares)	5,691,051	5,497,427
Common stock repurchase	$ 385	$ 265
2012 $250 million Repurchase Program
Equity, Class of Treasury Stock [Line Items]
Share repurchase program, authorized amount						$ 250
Common stock repurchase (in shares)	0	1,819,304	4,984,186
Common stock repurchase	$ 0	$ 83	$ 159

SHAREHOLDER'S EQUITY SHAREHOL70

SHAREHOLDER'S EQUITY SHAREHOLDERS' EQUITY - OTHER (Details) - shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Equity [Abstract]
Retirement of treasury stock	4,016,654
Treasury Stock, Shares	3,266,774	75,100

SHAREHOLDER'S EQUITY SHAREHOL71

SHAREHOLDER'S EQUITY SHAREHOLDERS' EQUITY - ACCUMULATED OTHER COMPREHENSIVE LOSS (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Equity [Abstract]
Unrealized gain on marketable securities considered available-for-sale	$ (3)	$ 0
Related to employee benefit plans	(288)	(298)
Related to interest rate derivatives	(12)	(12)
Accumulated other comprehensive loss	$ (303)	$ (310)

SPECIAL ITEMS SPECIAL ITEMS (De

SPECIAL ITEMS SPECIAL ITEMS (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Special Revenue	$ 0	$ 0	$ 192
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Operating Results		44
Special Item	32	(30)	0
Special Item, net of tax	$ 20
Special Item, net of tax, per diluted share	$ 0.15
Gain related to litigation settlement		$ 10
Original Estimate [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Change in Accounting Estimate, Description		12.00%
Revised Estimate [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Change in Accounting Estimate, Description		17.40%
Pension Plan [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Settlement expense (special item)	$ (14)	$ 0	$ 0

STOCK-BASED COMPENSATION PLAN73

STOCK-BASED COMPENSATION PLANS (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 17	$ 16	$ 16
Tax benefit related to stock-based compensation	7	6	6
Unrecognized stock-based compensation for non-vested options and awards	$ 11
Unrecognized stock-based compensation awards weighted-average period	8 months 12 days
Shares remaining available for future grants of either options or stock awards (in shares)	36,000,000
Shares authorized under stock-based compensation plans (in shares)	16,353,597
Stock options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 2	$ 3	$ 3
Unrecognized stock-based compensation for non-vested options and awards	$ 3
Unrecognized stock-based compensation awards weighted-average period	1 year
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Expected volatility	53.00%	65.00%	67.00%
Expected term	6 years	6 years	6 years
Risk-free interest rate	1.67%	1.87%	1.10%
Expected dividend yield	1.25%	1.25%	0.00%
Weighted-average grant date fair value per share (in dollars per share)	$ 28.71	$ 21.70	$ 14.74
Estimated fair value of options granted (millions)	$ 3	$ 3	$ 3
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding, beginning balance (in shares)	707,688
Granted (in Shares)	93,660
Exercised (in shares)	(255,717)
Canceled (in shares)	(1)
Forfeited or expired (in shares)	(5,285)
Outstanding, ending balance (in shares)	540,345	707,688
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Outstanding, beginning balance, Weighted-Average Exercise Price Per Share (in dollars per share)	$ 21.57
Granted, Weighted-Average Exercise Price Per Share (in dollars per share)	65.30
Exercised, Weighted-Average Exercise Price Per Share (in dollars per share)	15.97
Canceled, Weighted-Average Exercise Price Per Share (in dollars per share)	38.76
Fofeited or expired, Weighted-Average Exercise Price Per Share (in dollars per share)	44.56
Outstanding, ending balance, Weighted-Average Exercise Price Per Share (in dollars per share)	$ 31.58	$ 21.57
Outstanding, Weighted-Average Contractual Life	6 years 3 months 18 days	6 years 4 months 24 days
Outstanding, Aggregate Intrinsic Value	$ 26	$ 27
Exercisable, Outstanding (in shares)	195,873
Exercisable, Weighted-Average Exercise Price Per Share (in dollars per share)	$ 18.62
Exercisable, Weighted-Average Contractual Life	5 years 7 months 6 days
Exercisable, Aggregate Intrinsic Value	$ 12
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest [Abstract]
Vested or expected to vest, Shares	539,868
Vested or expected to vest, Weighted-Average Exercise Price Per Share (in dollars per share)	$ 31.57
Vested or expected to vest, Weighted-Average Contractual Life	6 years 3 months 18 days
Vested or expected to vest, Aggregate Intrinsic Value	$ 26
Intrinsic value of option exercises	14	20	19
Cash received from stock option exercises	4	6	8
Tax benefit related to stock option exercises	5	7	7
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Additional Disclosures [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested in Period, Fair Value	3	2	3
Stock awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	11	$ 10	10
Unrecognized stock-based compensation for non-vested options and awards	$ 8
Unrecognized stock-based compensation awards weighted-average period	8 months 12 days
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Non-vested, beginning balance (in shares)	1,027,390
Granted (in shares)	244,874
Vested (in shares)	(764,322)
Forfeited (in shares)	(37,227)
Non-vested, ending balance (in shares)	470,715	1,027,390
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Additional Disclosures [Abstract]
Non-vested, beginning balance, Weighted-Average Grant Date Fair Value (in dollars per share)	$ 26.19
Granted, Weighted-Average Grant Date Fair Value (in dollars per share)	50.94
Vested, Weighted-Average Grant Date Fair Value (in dollars per share)	26.33
Forfeited, Weighted-Average Grant Date Fair Value (in dollars per share)	35.86
Non-vested, ending balance, Weighted-Average Price Per Share (in dollars per share)	$ 38.09	$ 26.19
Non-vested, Weighted-Average Contractual Life	9 months 18 days	7 months 6 days
Non-vested, Total Instrinsic Value (in dollars)	$ 38	$ 61
Deferred stock awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	1	1	1
Employee stock purchase plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 3	$ 2	$ 2
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Granted (in shares)	281,058	298,283	171,227
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Additional Disclosures [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Purchase Price of Common Stock, Percent	85.00%
Share-based Compensation Arrangement by Share-based Payment Award, Maximum Employee Subscription Rate	10.00%

OPERATING SEGMENT INFORMATION74

OPERATING SEGMENT INFORMATION (Details) $ in Millions		12 Months Ended
		Dec. 31, 2015USD ($)airlinesegment	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)
Segment Reporting Information [Line Items]
Number of operating airlines | airline		2
Number of operating segments | segment		3
Operating revenues
Passenger, Mainline		$ 3,939	$ 3,774	$ 3,490
Passenger, Regional		854	805	777
Total passenger revenue		4,793	4,579	4,267
CPA revenues		0	0	0
Freight and mail		108	114	113
Other Net and Special Revenue		697	675	776
Total Operating Revenues		5,598	5,368	5,156
Operating expenses
Operating expenses, excluding fuel		3,346	2,988	2,851
Economic fuel		954	1,418	1,467
Total Operating Expenses		4,300	4,406	4,318
Nonoperating income (expense)
Interest income		21	21	18
Interest expense		(42)	(48)	(56)
Other		35	40	16
Nonoperating Income (Expense) Total		14	13	(22)
Income (loss) before income tax		1,312	975	816
Income before income tax			975	816
Depreciation		320	294	270
Capital expenditures		831	694	566
Total assets		6,533	6,064
Air Group Adjusted [Member]
Operating revenues
Passenger, Mainline	[1]	3,939	3,774	3,490
Passenger, Regional	[1]	854	805	777
Total passenger revenue	[1]	4,793	4,579	4,267
CPA revenues	[1]	0	0	0
Freight and mail	[1]	108	114	113
Other Net and Special Revenue	[1]	697	675	584
Total Operating Revenues	[1]	5,598	5,368	4,964
Operating expenses
Operating expenses, excluding fuel	[1]	3,314	3,018	2,851
Economic fuel	[1]	954	1,441	1,475
Total Operating Expenses	[1]	4,268	4,459	4,326
Nonoperating income (expense)
Interest income	[1]	21	21	18
Interest expense	[1]	(42)	(48)	(56)
Other	[1]	35	40	16
Nonoperating Income (Expense) Total	[1]	14	13	(22)
Income (loss) before income tax	[1]	1,344	922	616
Alaska Airlines [Member]
Nonoperating income (expense)
Depreciation	[2]	268	243	223
Capital expenditures	[2]	821	659	494
Total assets	[2]	8,129	6,665
Alaska Mainline [Member]
Operating revenues
Passenger, Mainline		3,939	3,774	3,490
Passenger, Regional		0	0	0
Total passenger revenue		3,939	3,774	3,490
CPA revenues		0	0	0
Freight and mail		103	109	109
Other Net and Special Revenue		621	592	513
Total Operating Revenues		4,663	4,475	4,112
Operating expenses
Operating expenses, excluding fuel		2,653	2,417	2,293
Economic fuel		823	1,251	1,294
Total Operating Expenses		3,476	3,668	3,587
Nonoperating income (expense)
Interest income		19	20	18
Interest expense		(28)	(32)	(38)
Other		28	39	25
Nonoperating Income (Expense) Total		19	27	5
Income (loss) before income tax		1,206	834	530
Alaska Regional [Member]
Operating revenues
Passenger, Mainline		0	0	0
Passenger, Regional		854	805	777
Total passenger revenue		854	805	777
CPA revenues		0	0	0
Freight and mail		5	5	4
Other Net and Special Revenue		72	78	66
Total Operating Revenues		931	888	847
Operating expenses
Operating expenses, excluding fuel		695	623	585
Economic fuel		131	190	181
Total Operating Expenses		826	813	766
Nonoperating income (expense)
Interest income		0	0	0
Interest expense		0	0	0
Other		0	(1)	(12)
Nonoperating Income (Expense) Total		0	(1)	(12)
Income (loss) before income tax		105	74	69
Horizon [Member]
Operating revenues
Passenger, Mainline		0	0	0
Passenger, Regional		0	0	0
Total passenger revenue		0	0	0
CPA revenues		408	371	368
Freight and mail		0	0	0
Other Net and Special Revenue		4	5	5
Total Operating Revenues		412	376	373
Operating expenses
Operating expenses, excluding fuel		375	349	341
Economic fuel		0	0	0
Total Operating Expenses		375	349	341
Nonoperating income (expense)
Interest income		0	0	0
Interest expense		(10)	(12)	(14)
Other		1	2	2
Nonoperating Income (Expense) Total		(9)	(10)	(12)
Income (loss) before income tax		28	17	20
Depreciation		52	51	47
Capital expenditures		10	35	72
Total assets		718	809
Parent [Member]
Nonoperating income (expense)
Depreciation		0	0	0
Total assets		4,734	3,551
Intersegment Eliminations
Operating revenues
Passenger, Mainline		0	0	0
Passenger, Regional		0	0	0
Total passenger revenue		0	0	0
CPA revenues		(408)	$ (371)	(368)
Freight and mail		0		0
Other Net and Special Revenue		0		0
Total Operating Revenues		(408)	$ (371)	(368)
Operating expenses
Operating expenses, excluding fuel		(409)	(371)	(368)
Economic fuel		0	0	0
Total Operating Expenses		(409)	(371)	(368)
Nonoperating income (expense)
Interest income		2	1	0
Interest expense		(4)	(4)	(4)
Other		6	0	1
Nonoperating Income (Expense) Total		4	(3)	(3)
Income (loss) before income tax		5	(3)	(3)
Total assets		(7,048)	(4,961)
Special Charges [Member]
Operating revenues
Passenger, Mainline	[3]	0	0	0
Passenger, Regional	[3]	0	0	0
Total passenger revenue	[3]	0	0	0
CPA revenues	[3]	0	0	0
Freight and mail	[3]	0	0	0
Other Net and Special Revenue	[3]	0	0	192
Total Operating Revenues	[3]	0	0	192
Operating expenses
Operating expenses, excluding fuel	[3]	32	(30)	0
Economic fuel	[3]	0	(23)	(8)
Total Operating Expenses	[3]	32	(53)	(8)
Nonoperating income (expense)
Interest income	[3]	0	0	0
Interest expense	[3]	0	0	0
Other	[3]	0	0	0
Nonoperating Income (Expense) Total	[3]	0	0	0
Income (loss) before income tax	[3]	$ (32)	$ 53	$ 200
[1]	The 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.
[2]	There are no depreciation expenses, capital expenditures or assets associated with purchased capacity flying at Alaska Regional.
[3]	Includes accounting adjustments related to mark-to-market fuel-hedge accounting charges (all years), pension settlement charge (2015), litigation-related matter (2015), non-cash curtailment gain (2014), a gain related to a legal matter (2014), and Special mileage plan revenue (2013).