Alaska Air (ALK) 10-K 14 Feb 24 2023 FY Annual report Financial data

Cover

Cover - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2023	Jan. 31, 2024	Jun. 30, 2023
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2023
Document Transition Report	false
Entity File Number	1-8957
Entity Registrant Name	ALASKA AIR GROUP, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	91-1292054
Entity Address, Address Line One	19300 International Boulevard
Entity Address, City or Town	Seattle
Entity Address, State or Province	WA
Entity Address, Postal Zip Code	98188
City Area Code	206
Local Phone Number	392-5040
Title of 12(b) Security	Common Stock, $0.01 Par Value
Trading Symbol	ALK
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		126,048,946
Entity Public Float			$ 6.7
Amendment Flag	false
Document Fiscal Year Focus	2023
Entity Central Index Key	0000766421
Document Fiscal Period Focus	FY
Current Fiscal Year End Date	--12-31
ICFR Auditor Attestation Flag	true
Security Exchange Name	NYSE
Document Information [Line Items]
Auditor Firm ID	185
Auditor Location	Seattle, WA
Auditor Name	KPMG LLP
Document Financial Statement Error Correction [Flag]	false
Entity Shell Company	false

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Operating Revenues
Total Operating Revenues	$ 10,426	$ 9,646	$ 6,176
Operating Expenses
Wages and benefits	3,041	2,640	2,218
Payroll Support Program Grant Recognized	0	0	(914)
Variable incentive pay	200	257	151
Aircraft fuel, including hedging gains and losses	2,641	2,668	1,279
Aircraft maintenance	488	424	364
Aircraft rent	208	291	254
Landing fees and other rentals	680	581	555
Contracted services	389	329	235
Selling expenses	303	295	173
Depreciation and amortization	451	415	394
Cost of Services, Catering	241	197	139
Third-party regional carrier expense	218	182	147
Other operating expenses	729	717	507
Special Items - Impairment charges and other	392	496	(1)
Restructuring Charges	0	0	(10)
Special items—other	51	84	(10)
Total Operating Expenses	10,032	9,576	5,491
Operating Income (Loss), Total	394	70	685
Nonoperating Income (Expense) [Abstract]
Investment Income, Interest	80	53	25
Interest Expense	(121)	(108)	(128)
Interest Costs Capitalized Adjustment	27	14	11
Special Items - Net non-operating	(18)	0	0
Other - net	(39)	50	36
Nonoperating Income (Expense) Total	(71)	9	(56)
Income before income tax	323	79	629
Income Tax Expense, Before Tax Cuts and Jobs Act of 2017	88	21	151
Income tax expense	88	21	151
Net Income	$ 235	$ 58	$ 478
Basic earnings per share	$ 1.84	$ 0.46	$ 3.82
Diluted earnings per share	$ 1.83	$ 0.45	$ 3.77
Shares used for computation:
Basic	127,375	126,657	125,063
Diluted	128,708	127,899	126,775
Mileage Plan Services, Other [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	$ 648	$ 590	$ 461
Cargo and Freight [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	252	248	216
Passenger Revenue [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	9,526	8,808	5,499
Passenger Revenue [Member] | Passenger [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	9,526	8,808	5,499
Mileage Plan Revenue [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	1,682	1,521	1,100
Mileage Plan Revenue [Member] | Passenger [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	1,034	931	639
Mileage Plan Revenue [Member] | Mileage Plan Services, Other [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	648	590	461
Cargo and Other Revenue [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	252	248	216
Cargo and Other Revenue [Member] | Cargo and Freight [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	$ 252	$ 248	$ 216

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Current Assets
Cash and cash equivalents	$ 281	$ 338
Marketable securities	1,510	2,079
Total cash and marketable securities	1,791	2,417
Receivables - net	383	296
Inventories and supplies - net	116	104
Prepaid Expense	176	163
Other Assets, Current	239	60
Total Current Assets	2,705	3,040
Property and Equipment
Aircraft and other flight equipment	10,425	9,053
Other property and equipment	1,814	1,661
Deposits for future flight equipment	491	670
Property and Equipment	12,730	11,384
Less accumulated depreciation and amortization	4,342	4,127
Total Property and Equipment - Net	8,388	7,257
Other Assets
Operating Lease, Right-of-Use Asset	1,195	1,471
Goodwill and intangible assets	2,033	2,038
Other noncurrent assets	292	380
Total Other Assets	3,520	3,889
Total Assets	14,613	14,186
Current Liabilities
Accounts payable	207	221
Accrued wages, vacation and payroll taxes	584	619
Other accrued liabilities	800	846
Operating Lease, Liability, Current	158	228
Current portion of long-term debt	353	276
Total Current Liabilities	4,459	4,493
Long-Term Debt, Net of Current Portion	2,182	1,883
Other Liabilities and Credits
Operating Lease, Liability, Noncurrent	1,125	1,393
Deferred Income Tax Liabilities, Net	695	574
Deferred revenue	1,382	1,374
Obligation for pension and postretirement medical benefits	362	348
Other liabilities	295	305
Total Other Liabilities and Credits	3,859	3,994
Commitments and Contingencies
Preferred stock, par value	$ 0.01
Preferred stock, shares authorized	5,000,000
Shareholders' Equity
Preferred stock, $0.01 par value, Authorized: 5,000,000 shares, none issued or outstanding	$ 0	$ 0
Common stock, shares, outstanding	126,090,353	127,533,916
Common stock, shares issued	138,960,830	136,883,042
Common stock, $0.01 par value, Authorized: 400,000,000 shares, Issued: 2023 - 138,960,830 shares; 2022 - 136,883,042 shares, Outstanding: 2023 - 126,090,353 shares; 2022 - 127,533,916 shares	$ 1	$ 1
Capital in excess of par value	$ 695	$ 577
Treasury Stock, Common, Shares	9,349,944	12,870,477
Treasury stock (common), at cost: 2023 - 12,870,477 shares; 2022 - 9,349,944 shares	$ (819)	$ (674)
Accumulated other comprehensive loss	(299)	(388)
Retained earnings	4,535	4,300
Shareholders' Equity Total	4,113	3,816
Total Liabilities and Shareholders' Equity	$ 14,613	14,186
Common stock, shares authorized	400,000,000
Common stock, par value	$ 0.01
Air Traffic Liability
Current Liabilities
Air traffic liability	$ 1,136	1,180
Mileage Plan Revenue [Member]
Current Liabilities
Air traffic liability	$ 1,221	$ 1,123

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Shareholders' Equity:
Preferred stock, par value	$ 0.01
Preferred stock, shares authorized	5,000,000
Common stock, par value	$ 0.01
Common stock, shares authorized	400,000,000
Common stock, shares issued	138,960,830	136,883,042
Treasury Stock, Common, Shares	9,349,944	12,870,477
Virgin Group trademark license agreement
Shareholders' Equity:
Loss Contingency, Damages Sought, Value	$ 8

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE OPERATIONS - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Net Income	$ 235	$ 58	$ 478
Related to marketable securities:
Marketable securities, net of tax	46	(76)	(27)
Related to employee benefit plans:
Employee benefit plans, net of tax	48	(67)	246
Related to interest rate derivative instruments:
Interest rate derivative instruments, net of tax	(5)	17	13
Other comprehensive income (loss)	89	(126)	232
Comprehensive income	$ 324	$ (68)	$ 710

CONSOLIDATED STATEMENTS OF SHAR

CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) $ in Millions	Total	Common Stock	Capital in Excess of Par Value	Treasury Stock, Common	Accumulated Other Comprehensive Loss	Retained Earnings
Stockholders' Equity at Dec. 31, 2020	$ 2,988	$ 1	$ 391	$ (674)	$ (494)	$ 3,764
Common Stock Outstanding at Dec. 31, 2020		124,217,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	478					478
Other comprehensive income (loss)	232				232
Stock-based compensation	44		44
Adjustments to Additional Paid in Capital, Warrant Issued	16		16
Stock issued for employee stock purchase plan (in shares)		1,255,000
Stock issued for employee stock purchase plan	48		48
Stock issued under stock plans (in shares)		424,000
Stock issued under stock plans	(5)		(5)
Stockholders' Equity at Dec. 31, 2021	3,801	$ 1	494	(674)	(262)	4,242
Common Stock Outstanding at Dec. 31, 2021		125,906,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-Based Compensation Arrangement by Share-Based Payment Award, Shares Issued in Period		10,000
Net Income	58					58
Other comprehensive income (loss)	(126)				(126)
Stock-based compensation	35		35
Stock issued for employee stock purchase plan (in shares)		1,293,000
Stock issued for employee stock purchase plan	54		54
Stock issued under stock plans (in shares)		318,000
Stock issued under stock plans	(6)		(6)
Stockholders' Equity at Dec. 31, 2022	$ 3,816	$ 1	577	(674)	(388)	4,300
Common Stock Outstanding at Dec. 31, 2022	127,533,916	127,534,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-Based Compensation Arrangement by Share-Based Payment Award, Shares Issued in Period		17,000
Net Income	$ 235					235
Other comprehensive income (loss)	$ 89				89
Common stock repurchase (in shares)	(3,520,533)	(3,521,000)
Common stock repurchase	$ (145)			(145)
Stock-based compensation	60		60
Stock issued for employee stock purchase plan (in shares)		1,855,000
Stock issued for employee stock purchase plan	59		59
Stock issued under stock plans (in shares)		205,000
Stock issued under stock plans	(1)		(1)
Stockholders' Equity at Dec. 31, 2023	$ 4,113	$ 1	$ 695	$ (819)	$ (299)	$ 4,535
Common Stock Outstanding at Dec. 31, 2023	126,090,353	126,090,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-Based Compensation Arrangement by Share-Based Payment Award, Shares Issued in Period		17,000

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Cash flows from operating activities:
Net Income	$ 235	$ 58	$ 478
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	451	415	394
Stock-based compensation and other	85	42	51
Special Items - Impairment charges and other (noncash)	371	496	(1)
Special items - labor and related (noncash)	51	0	0
Restructuring Charges	0	0	(10)
Changes in certain assets and liabilities:
Changes in deferred income taxes	81	22	104
(Increase) decrease in accounts receivable	(19)	(45)	(69)
Increase (decrease) in air traffic liability	(44)	17	90
Increase in deferred revenue	106	139	81
Pension contribution	0	0	(100)
Proceeds from Income Tax Refunds	0	295	3
Other - net	(267)	(21)	9
Net cash provided by operating activities	1,050	1,418	1,030
Property and equipment additions:
Aircraft and aircraft purchase deposits	(1,055)	(1,272)	(68)
Other flight equipment	(197)	(208)	(126)
Other property and equipment	(242)	(191)	(98)
Total property and equipment additions	(1,494)	(1,671)	(292)
Purchases of marketable securities	(536)	(1,797)	(4,301)
Sales and maturities of marketable securities	1,152	2,252	3,595
Proceeds from Sale of Productive Assets	32	4	2
Other investing activities	(118)	(6)	(12)
Net cash used in investing activities	(964)	(1,218)	(1,008)
Cash flows from financing activities:
Proceeds from issuance of long-term debt, net of issuance costs	411	0	363
Long-term debt payments	(282)	(385)	(1,334)
Common stock repurchases	(137)	0	0
Other financing activities	(139)	60	57
Net cash used in financing activities	(147)	(325)	(914)
Net decrease in cash and cash equivalents	(61)	(125)	(892)
Cash, cash equivalents, and restricted cash at beginning of period	369	494	1,386
Cash, cash equivalents, and restricted cash at end of period	308	369	494
Cash and cash equivalents	$ 281	$ 338	$ 470

CONSOLIDATED STATEMENTS OF CA_2

CONSOLIDATED STATEMENTS OF CASH FLOWS (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Cash paid during the year for:
Interest, net of amount capitalized	$ 105	$ 71	$ 109
Income taxes, net of refunds received	15	0	48
Noncash transactions [Abstract]
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	178	461	273
Operating Lease Converted To Finance Lease	505	0	0
Noncash or Part Noncash Acquisition, Fixed Assets Acquired	179	0	0
Reconciliation of cash, cash equivalents, and restricted cash:
Cash and cash equivalents	281	338	470
Restricted Cash and Investments, Current	27	31	24
Total cash, cash equivalents, and restricted cash at end of the period	$ 308	$ 369	$ 494

GENERAL AND SUMMARY OF SIGNIFIC

GENERAL AND SUMMARY OF SIGNIFICANT ACCOUNTING	12 Months Ended
	Dec. 31, 2023
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 (Air Group, or the Company), and its primary subsidiaries, Alaska Airlines, Inc. (Alaska) and Horizon Air Industries, Inc. (Horizon). Our consolidated financial statements also include McGee Air Services, a ground services subsidiary of Alaska. The Company conducts substantially all of its operations through these subsidiaries. All 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 (GAAP) and their preparation requires the use of management’s estimates. Actual results may differ from these estimates. Certain rows, columns, figures, or percentages may not recalculate due to rounding. 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 $14 million and $9 million at December 31, 2023 and 2022, 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's restricted cash balances are not material and are classified as Other noncurrent assets. Restricted cash balances are primarily used to guarantee various letters of credit, self-insurance programs, or other contractual rights. They consist 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 are reflected in accumulated other comprehensive income (loss). The Company evaluates the investment portfolio on a quarterly basis for expected credit losses. The Company uses a systematic methodology that groups assets by relevant market sector, and considers available quantitative and qualitative evidence in evaluating potential allowances for credit losses. If the cost of an investment exceeds its fair value, management evaluates, among other factors, general market and industry conditions, credit quality of debt instrument issuers, the duration and extent to which the fair value is less than cost, the Company's intent and ability to hold, or plans to sell, the investment. Once a decline in fair value is determined to be the result of an expected credit loss, an allowance is recorded to Other—net in the consolidated statements of operations. Receivables - net Receivables primarily consist of amounts due from credit card processors for the sale of passenger tickets, from the Company's affinity card partner for the purchase of miles under our loyalty program, and from taxing authorities for certain tax receivables. Given the nature of these receivables, reserves are immaterial to the overall balance. In 2023, certain A321neos were sold to a third-party with full payment for the aircraft occurring in January 2024. The balance owed to Alaska as of December 31, 2023 for these transactions was classified within Receivables - net. 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 expendable inventories was $60 million and $55 million at December 31, 2023 and 2022. Removals from the reserve in 2023 were immaterial. Inventory and supplies - net also includes fuel inventory of $31 million and $38 million at December 31, 2023 and 2022. 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: Estimated Useful Life Estimated Salvage Value Aircraft and other flight equipment: B737 and E175 aircraft 20 to 25 years 10% Buildings 25 to 40 years 10% Minor building and land improvements 10 years —% Capitalized leases and leasehold improvements Generally shorter of lease term or —% Computer hardware and software 3 to 10 years —% Other furniture and equipment 5 to 10 years —% Near the end of an asset's estimated useful life, management updates the salvage value estimates based on current market conditions and expected use of the asset. Repairable and rotable aircraft parts are included in Aircraft and other flight equipment, and are depreciated over the associated fleet life. Capitalized interest, 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. 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 at which identifiable cash flows are largely independent of the cash flows of other groups of assets and liabilities, which is generally the fleet level. 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 . For these purposes, the fair value is estimated using a combination of Level 2 inputs, including published market value estimates for the assets being assessed, and Level 3 inputs, including Company-specific and asset-specific indicators. Goodwill Goodwill represents the excess of purchase price over the fair value of the related net assets acquired in the Company's acquisition of Virgin America and is not amortized. The total balance of goodwill is associated with the Mainline reporting unit. The Company reviews goodwill for impairment annually in the fourth quarter, or more frequently if events or circumstances indicate that an impairment may exist. The assessment utilizes either a qualitative or quantitative approach. The qualitative approach considers factors such as Alaska Air Group market capitalization and other market trends, and unobservable inputs, including Company specific cash flow and performance information. If it is determined that it is more likely than not that the asset may be impaired, management utilizes a quantitative approach to assess the asset's fair value and the amount of impairment and a charge may be recorded. In 2023, the fair value of the Mainline reporting unit exceeded its carrying value. Intangible Assets Intangible assets are comprised primarily of indefinite-lived airport slots recorded in conjunction with the acquisition of Virgin America. Indefinite-lived intangibles were recorded at fair value upon acquisition and are not amortized, but are tested at least annually for impairment using a similar methodology to goodwill, as described above. Aircraft Maintenance Deposits Certain Airbus leases include contractually required maintenance deposit payments to the lessor, which collateralize the lessor for future maintenance events should the Company not perform required maintenance. Most of the lease agreements provide that maintenance deposits are reimbursable upon completion of the major maintenance event in an amount equal to the lesser of (i) the amount qualified for reimbursement from maintenance deposits held by the lessor associated with the specific major maintenance event or (ii) the qualifying costs related to the specific major maintenance event. The Company establishes accounting maintenance deposits as assets on the balance sheet using estimates of the anticipated timing and cost of the specific major maintenance events, such that the accounting deposits do not exceed the amount qualified for reimbursement. Aircraft maintenance deposits recorded on the consolidated balance sheets were $70 million and $140 million as of December 31, 2023 and December 31, 2022. As of December 31, 2023, all maintenance deposits are presented within Other current assets on the consolidated balance sheets. Any expense associated with aircraft maintenance deposits which may not ultimately be claimable in the standard course of operating the aircraft is included in Aircraft maintenance in the consolidated statements of operations. Following the Company's decision in early 2022 to exit the Airbus fleet before contractual return timelines, expense associated with aircraft maintenance deposits, including impairment of those deposits which will not be claimed, was recognized ratably over the remaining operating period of the respective aircraft, and classified within Special items - fleet transition and other in the consolidated statement of operations. See Note 2 for further discussion of these special items. Leased Aircraft Return Costs Costs to return leased aircraft are accrued when the costs are probable and reasonably estimable, usually over the twelve months prior to the lease return, unless a determination is made to remove the leased asset from operation. If the leased aircraft is removed from the operating fleet, the estimated cost to return is accrued at the time of removal. If a leased aircraft has a known early retirement date in the future, the estimated cost to return is accrued through the retirement date. 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 may not be known with certainty until lease termination. As leased aircraft are returned, payments made reduce the outstanding lease return liability. As of December 31, 2023, the total outstanding liability is $112 million and is included in Other accrued liabilities, compared to $186 million included in Other accrued liabilities and $91 million included in Other liabilities as of December 31, 2022. Expense associated with lease returns in the standard course of operating the aircraft is included in Aircraft maintenance in the consolidated statements of operations. Expense associated with lease returns when aircraft are permanently parked or anticipated to be removed from the fleet before its contractual return date is recorded as a charge at the date the aircraft is permanently parked, regardless of contractual return date, and is classified within Special items - fleet transition and other in the consolidated statements of operations. See Note 2 for further discussion of these special items. Airframe and Engine Maintenance Expense Maintenance and repairs on our aircraft, other than engine maintenance on certain 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 B737-800, B737-900ER, and E175 engines are covered under power-by-the-hour agreements with third parties, whereby the Company pays a determinable amount, and transfers risk, to a third party. For these agreements, the Company expenses the contract amounts based on engine usage. Advertising Expenses The Company's advertising expenses include advertising, sponsorship and promotional costs. Advertising production costs are expensed as incurred. Advertising expense was $78 million, $85 million, and $63 million during the years ended December 31, 2023, 2022 and 2021. Derivative Financial Instruments The Company's operations are significantly impacted by changes in aircraft fuel prices and interest rates. In an effort to manage exposure to these risks, the Company has entered 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 are recognized in AOCL or in the consolidated statements of operations, depending on the nature of the instrument. Cash flows related to these derivative instruments are classified as operating cash flows within the consolidated statements of cash flows. The Company does not apply hedge accounting to its derivative fuel hedge contracts, nor does it hold or issue them for trading purposes. For cash flow hedges related to 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. As of December 31, 2023, the Company has suspended its crude oil hedge program. Our final position will settle in the first quarter of 2025. Income Taxes The Company uses the asset and liability approach for accounting for 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. As of December 31, 2023, there is a partial valuation allowance against net deferred tax assets. The Company accounts for unrecognized tax benefits in accordance with the applicable accounting standards. See Note 8 to the consolidated financial statements for more discussion of income taxes. Stock-Based Compensation Accounting standards require companies to recognize expense over the service period based on the fair value of stock options and other equity-based compensation issued to employees estimated 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. Recent Accounting Pronouncements In November 2023, the FASB issued ASU 2023-07, Segment Reporting (Topic 280), which requires public entities to disclose information about their reportable segments’ significant expenses and other segment items on an interim and annual basis. ASU 2023-07 is effective for fiscal years beginning after December 15, 2023, and for interim periods within fiscal years beginning after December 15, 2024, with early adoption permitted. The Company is currently evaluating the impact of adopting ASU 2023-07. In December 2023, the FASB issued ASU 2023-09, Income Taxes (Topic 740), which requires public entities to provide disclosure of specific categories in the rate reconciliation, as well as disclosure of income taxes paid disaggregated by jurisdiction on an annual basis. ASU 2023-09 is effective for fiscal years beginning after December 15, 2024, with early adoption permitted. The Company is currently evaluating the impact of adopting ASU 2023-09.

FLEET TRANSITION

FLEET TRANSITION	12 Months Ended
	Dec. 31, 2023
Property, Plant and Equipment [Abstract]
Fleet Transition and Related Activities Disclosure	NOTE 2. FLEET TRANSITION In 2022, the Company announced plans to accelerate the transition of its mainline operations to an all-Boeing fleet. It also announced plans to transition its regional operations to an all-Embraer fleet. The removal of all A320 and Q400 aircraft from operating service was completed in January 2023. The removal of all A321neo aircraft from operating service was completed in September 2023. During 2023, Alaska reached agreements with multiple lessors to exit its ten A321neo operating leases and purchase the aircraft. Alaska also reached an agreement to subsequently sell the ten aircraft to a third party. Nine aircraft purchases and eight sales closed by December 31, 2023. The remaining purchase and sales closed in January 2024. As a result of the purchase agreement with the lessor, the operating lease associated with the aircraft that was not purchased by December 31, 2023 was considered modified, and upon evaluation was reclassified as a finance lease. Valuation of Long-Lived Assets The Company reviews its long-lived assets for impairment whenever events or circumstances indicate that the total carrying value of an asset or asset group may not be recoverable. In 2023, the Company recorded impairment charges of $278 million related to the A321neo fleet, reflecting the amount by which carrying value exceeded fair value of the aircraft. This charge was included within Special items - fleet transition and other in the consolidated statements of operations. Other Fleet Related Disclosure As of December 31, 2023, the finance lease associated with the one A321neo that had not been purchased was included within Current portion of long-term debt and finance leases in the consolidated balance sheets. The two A321neo aircraft that had not been sold to the third party as of the balance sheet date were included within Other current assets. There were also two A321neo aircraft sales to the third party that transacted in 2023 but were not paid in full until January 2024. The receivable balance associated with these transactions was included within Receivables - net on the consolidated balance sheets. Special charges were also recognized during the year for other fleet transition costs, including accelerated aircraft ownership expenses, certain aircraft maintenance work performed as a result of the fleet retirements, adjustments to estimated costs to return the A320 fleet, and penalty rent for Airbus aircraft which have not yet been returned to the lessor as of the lease expiration date. Interest expense associated with the finance leases of $18 million for 2023 was recognized within Special items - net non-operating in the consolidated statements of operations. The following table summarizes our special charges for fleet transition costs related to our Airbus and Q400 fleets for the twelve months ended December 31, 2023 and 2022: Twelve Months Ended December 31, (in millions) 2023 2022 Impairment of long-lived assets (a) $ 268 $ 70 Other costs (b) 124 426 Special items - fleet transition and other $ 392 $ 496 (a) Net of immaterial gains associated with the sale of certain Q400 aircraft in 2023 that were previously impaired in 2022. (b) Inclusive of immaterial activity associated with the agreement to acquire Hawaiian Airlines recorded in 2023 and $15 million associated with certain incremental litigation accrual costs recorded in 2022.

REVENUE FROM CONTRACTS WITH CUS

REVENUE FROM CONTRACTS WITH CUSTOMERS (Notes)	12 Months Ended
	Dec. 31, 2023
Revenue from Contracts with Customer [Abstract]
Revenue from Contract with Customer [Text Block]	NOTE 3. REVENUE Ticket revenue is recorded as Passenger revenue, and represents the primary source of the Company's revenue. Also included in Passenger revenue is passenger ancillary revenue such as checked-bag fees, on-board food and beverage, and certain revenue from the frequent flyer program. Mileage Plan other revenue includes brand and marketing revenue from our co-branded credit card and other partners and certain interline frequent flyer revenue, net of commissions. Cargo and other revenue includes freight and mail revenue, and to a lesser extent, other ancillary revenue products such as lounge membership and certain commissions. The Company disaggregates revenue by segment in Note 14. The level of detail within the Company’s consolidated statements of operations, segment disclosures, and in this footnote depict the nature, amount, timing and uncertainty of revenue and how cash flows are affected by economic and other factors. Passenger Ticket and Ancillary Services Revenue The primary performance obligation on a typical passenger ticket is to provide air travel to the passenger. Ticket revenue is collected in advance of travel and recorded as air traffic liability on the consolidated balance sheets. The Company satisfies its performance obligation and recognizes ticket revenue for each flight segment when the transportation is provided. Ancillary passenger revenue relates to items such as checked-bag fees and on-board food and beverage sales, all of which are provided at time of flight. As such, the obligation to perform these services is satisfied at the time of travel and is recorded with ticket revenue in Passenger revenue. Revenue is also recognized for tickets that are expected to expire unused, a concept referred to as “passenger ticket breakage.” Passenger ticket breakage is recorded at the intended travel date using estimates made at the time of sale based on the Company’s historical experience of expired tickets, and other facts such as program changes and modifications. Differences between advance passenger ticket breakage estimates and actual expirations are recognized as revenue when changes to estimate assumptions are observed or when tickets are no longer valid. In addition to selling tickets on its own marketed flights, Alaska has interline agreements with partner airlines under which it sells multi-city tickets with one or more segments of the trip flown by a partner airline, or it operates a connecting flight sold by a partner airline. Each segment in a connecting flight represents a separate performance obligation. Revenue on segments sold and operated by the Company is recognized as Passenger revenue in the gross amount of the allocated ticket price when the travel occurs, while the commission paid to the partner airline is recognized as a selling expense when the related transportation is provided. Revenue on segments operated by a partner airline is deferred for the full amount of the consideration received at the time the ticket is sold and, once the segment has been flown the Company records the net amount, after compensating the partner airline, as Cargo and other revenue. A portion of revenue from the Mileage Plan program is recorded in Passenger revenue. As members are awarded mileage credits on flown tickets, these credits become a distinct performance obligation to the Company. The Company allocates the transaction price to each performance obligation identified in a passenger ticket contract on a relative standalone selling price basis. The standalone selling price for loyalty mileage credits issued is discussed in the Loyalty mileage credits section of this Note below. The amount allocated to the mileage credits is deferred on the balance sheet. Once a member travels using a travel award redeemed with mileage credits on one of the Company's airline carriers, the revenue associated with those mileage credits is recorded as Passenger revenue. Taxes collected from passengers, including transportation excise taxes, airport and security fees, and other fees, are recorded on a net basis within Passenger revenue in the consolidated statements of operations. Passenger revenue recognized in the consolidated statements of operations (in millions): Twelve Months Ended December 31, 2023 2022 2021 Passenger ticket revenue, net of taxes and fees $ 8,016 $ 7,430 $ 4,533 Passenger ancillary revenue 476 447 327 Mileage Plan passenger revenue 1,034 931 639 Total Passenger revenue $ 9,526 $ 8,808 $ 5,499 As passenger tickets and related ancillary services are primarily sold via credit cards, certain amounts due from credit card processors are recorded as airline traffic receivables. These credit card receivables and receivables from our affinity credit card partner represent $243 million and $201 million on the consolidated balance sheets as of December 31, 2023 and 2022. For performance obligations with performance periods of less than one year, GAAP provides a practical expedient that allows the Company not to disclose the transaction price allocated to remaining performance obligations and the timing of related revenue recognition. As passenger tickets expire one year from ticketing, if unused or not exchanged, the Company elected to apply this practical expedient. Mileage Plan Loyalty Program Loyalty mileage credits The Company’s Mileage Plan loyalty program provides frequent flyer travel awards to program members based upon accumulated loyalty mileage credits. Mileage credits are earned through travel, purchases using the Mileage Plan co-branded credit card and purchases from other participating partners. Outstanding mileage credits have no expiry date. The Company offers redemption of mileage credits through free, discounted, or upgraded air travel on flights operated by Alaska and its regional partners or on one of its 30 partners, as well as redemption at partner hotels. The Company uses a relative standalone selling price to allocate consideration to material performance obligations in contracts with customers that include loyalty mileage credits. As directly observable selling prices for mileage credits are not available, the Company determines the standalone selling price of mileage credits primarily using actual ticket purchase prices for similar tickets flown, adjusted for the likelihood of redemption, or breakage. In determining similar tickets flown, the Company considers current market prices, class of service, type of award, and other factors. For mileage credits accumulated through travel on partner airlines, the Company uses actual consideration received from the partners. Revenue related to air transportation is deferred in the amount of the relative standalone selling price allocated to the loyalty mileage credits as they are issued. The Company satisfies its performance obligation when the mileage credits are redeemed and the related air transportation is delivered. The Company estimates breakage for the portion of loyalty mileage credits not expected to be redeemed using a statistical analysis of historical data, including source of mileage credit earned, slow-moving, and low-credit accounts, among other factors. The Company recognizes breakage proportionally as mileage credits are redeemed. The Company reviews the breakage rate used on an annual basis. Co-branded credit card agreements and other In addition to mileage credits, the co-branded credit card agreement, referred to herein as the Agreement, also includes performance obligations for waived bag fees, Companion Fare offers to purchase an additional ticket at a discount, marketing, priority boarding, and the use of intellectual property including the brand (unlimited access to the use of the Company’s brand and frequent flyer member lists), which is the predominant element in the Agreement. The co-branded card bank partner is the customer for some elements, including the brand and marketing, while the Mileage Plan member is the customer for other elements such as mileage credits, bag waivers, priority boarding and companion fares. At the inception of the Agreement, management estimated the selling price of each of the performance obligations. The objective was to determine the price at which a sale would be transacted if the product or service was sold on a stand-alone basis. The Company determined its best estimate of selling price for each element by considering multiple inputs and methods including, but not limited to, the estimated selling price of comparable travel, discounted cash flows, brand value, published selling prices, number of miles awarded, and number of miles redeemed. The Company estimated the selling prices and volumes over the term of the Agreement in order to determine the allocation of proceeds to each of the multiple deliverables. The estimates of the standalone selling prices of each element do not change subsequent to the original valuation of the contract unless the contract is materially modified, but the allocation between elements may change based upon the actual and updated projected volumes of each element delivered during the term of the contract. Consideration received from the bank is variable and is primarily from consumer spend on the card, among other items. The Company allocates consideration to each of the performance obligations, including mileage credits, waived bag fees, companion fares, and brand and marketing, using their relative standalone selling price. Because the performance obligation related to providing use of intellectual property including the brand is satisfied over time, it is recognized in Mileage Plan other revenue in the period that those elements are sold. The Company records passenger revenue related to the air transportation and certificates for discounted companion travel when the transportation is delivered. In contracts with non-bank partners, the Company has identified two performance obligations in most cases - travel and brand. The travel performance obligation is deferred until the transportation is provided in the amount of the estimated standalone selling price of the ticket, less breakage, and the brand performance obligation is recognized using the residual method as commission revenue when the brand element is sold. Mileage credit sales recorded under the residual approach are immaterial to the overall program. Partner airline loyalty Alaska has interline arrangements with certain airlines whereby its members may earn and redeem Mileage Plan credits on those airlines, and members of a partner airline’s loyalty program may earn and redeem frequent flyer program credits on flights operated by Alaska and its regional partners. When a Mileage Plan member earns credits on a partner airline, the partner airline remits a contractually-agreed upon fee to the Company which is deferred until credits are redeemed. When a Mileage Plan member redeems credits on a partner airline, the Company pays a contractually agreed upon fee to the other airline, which is netted against the revenue recognized associated with the award travel. When a member of a partner airline redeems frequent flyer credits on Alaska, the partner airline remits a contractually-agreed upon amount to the Company, recognized as Passenger revenue upon travel. If the partner airline’s member earns frequent flyer program credits on an Alaska flight, the Company remits a contractually-agreed upon fee to the partner airline and records a commission expense. Mileage Plan revenue included in the consolidated statements of operations (in millions): Twelve Months Ended December 31, 2023 2022 2021 Passenger revenue $ 1,034 $ 931 $ 639 Mileage Plan other revenue 648 590 461 Total Mileage Plan revenue $ 1,682 $ 1,521 $ 1,100 Mileage Plan other revenue is primarily brand and marketing revenue from our affinity card products. Cargo and Other Revenue The Company provides freight and mail services (cargo). The majority of cargo services are provided to commercial businesses and the United States Postal Service. The Company satisfies cargo service performance obligations and recognizes revenue when the shipment arrives at its final destination, or is transferred to a third-party carrier for delivery. The Company also earns other revenue for lounge memberships, hotel and car commissions, travel insurance, and certain other immaterial items not intrinsically tied to providing air travel to passengers. Revenue is recognized when these services are rendered and recorded as Cargo and other revenue. The transaction price for Cargo and other revenue is the price paid by the customer. Cargo and other revenue included in the consolidated statements of operations (in millions): Twelve Months Ended December 31, 2023 2022 2021 Cargo revenue $ 128 $ 133 $ 124 Other revenue 124 115 92 Total Cargo and other revenue $ 252 $ 248 $ 216 Air Traffic Liability and Deferred Revenue Passenger ticket and ancillary services liabilities The Company recognized Passenger revenue of $823 million and $700 million from the 2022 and 2021 year-end air traffic liability balance during the twelve months ended December 31, 2023 and 2022. Mileage Plan liabilities The total deferred revenue liability included on the consolidated balance sheets represents the remaining transaction price that has been allocated to Mileage Plan performance obligations not yet satisfied by the Company. In general, the current amounts will be recognized as revenue within 12 months and the long-term amounts will be recognized as revenue over a period of approximately three to four years. This period of time represents the average time that members have historically taken to earn and redeem miles. The Company records a receivable for amounts due from the affinity card partner and from other partners as mileage credits are sold until the payments are collected. The Company had $102 million and $83 million of such receivables as of December 31, 2023 and December 31, 2022. Mileage credits are combined into one homogeneous pool and are not specifically identifiable once deposited. As such, loyalty revenue disclosed earlier in this Note are comprised of miles that were part of the deferred revenue and liabilities balances at the beginning of the period and miles that were issued during the period. The table below presents a roll forward of the total frequent flyer liability (in millions): Twelve Months Ended December 31, 2023 2022 Total Deferred Revenue balance at January 1 $ 2,497 $ 2,358 Travel miles and companion certificate redemption - Passenger revenue (974) (878) Miles redeemed on partner airlines - Other revenue (117) (65) Increase in liability for mileage credits issued 1,197 1,082 Total Deferred Revenue balance at December 31 $ 2,603 $ 2,497 Selling Costs Certain costs such as credit card fees, travel agency and other commissions paid, as well as Global Distribution Systems booking fees, are incurred when the Company sells passenger tickets and ancillary services in advance of the travel date. The Company defers such costs and recognizes them as expenses when the travel occurs. Prepaid expense recorded on the consolidated balance sheets for such costs was $35 million and $33 million as of December 31, 2023 and December 31, 2022. The Company recorded related expense on the consolidated statements of operations of $334 million, $311 million and $90 million for the twelve months ended December 31, 2023, 2022, and 2021.

DERIVATIVE INSTRUMENTS

DERIVATIVE INSTRUMENTS	12 Months Ended
	Dec. 31, 2023
Derivative Instruments and Hedging Activities Disclosure [Abstract]
DERIVATIVE INSTRUMENTS	NOTE 4. DERIVATIVE INSTRUMENTS AND RISK MANAGEMENT Fuel Hedge Contracts The Company’s operations are dependent upon the price and availability of aircraft fuel. To manage economic risks associated with fluctuations in aircraft fuel prices, the Company has historically entered into call options for crude oil. As of December 31, 2023, the Company had outstanding fuel hedge contracts covering approximately 324 million gallons of crude oil that will be settled between January 2024 and March 2025. The hedge program was suspended in the fourth quarter of 2023. Interest Rate Swap Agreements The Company is exposed to market risk from adverse changes in variable interest rates on long-term debt. To manage this risk, the Company periodically enters into interest rate swap agreements. As of December 31, 2023, the Company had interest rate swap agreements with third parties designed to hedge the volatility of the underlying variable interest rates on $253 million of debt. All of the interest rate swap agreements stipulate that the Company pay a fixed interest rate and receive a floating interest rate over the term of the underlying contracts. All significant terms of the swap agreements match the terms of the underlying hedged items and have been designated as qualifying hedging instruments, which are accounted for as cash flow hedges. As qualifying cash flow hedges, the interest rate swaps are recognized at fair value on the balance sheet, and changes in the fair value are recognized in accumulated other comprehensive loss. 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 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 recognized in interest expense, if material. Fair Values of Derivative Instruments Fair values of derivative instruments on the consolidated balance sheet (in millions): 2023 2022 Fuel hedge contracts (not designated as hedges) Other current assets $ 10 $ 33 Other assets 1 11 Interest rate swaps (designated as hedges) Other current assets 6 8 Other noncurrent assets 2 7 (Losses)/gains in accumulated other comprehensive loss (AOCL) (7) 23 The net cash paid for fuel hedge positions was $29 million during 2023, compared to net cash received of $130 million during 2022 and net cash received of $38 million during 2021. Pretax effect of derivative instruments on earnings and AOCL (in millions): 2023 2022 2021 Fuel hedge contracts (not designated as hedges) (Losses)/gains recognized in Aircraft fuel $ (62) $ 93 $ 104 Interest rate swaps (designated as hedges) (Losses)/gains recognized in other comprehensive income (OCI) (7) 23 17 Gains related to interest rate swaps on variable rate debt of $8 million were recognized in interest expense during 2023. The amounts shown as recognized in OCI are prior to the losses recognized in aircraft rent during the period. The Company expects to reclassify from OCI $6 million in interest income within the next twelve months.

LONG-TERM DEBT

LONG-TERM DEBT	12 Months Ended
	Dec. 31, 2023
Debt Disclosure [Abstract]
LONG-TERM DEBT	NOTE 6. LONG-TERM DEBT Long-term debt obligations on the consolidated balance sheet (in millions): 2023 2022 Fixed-rate notes payable due through 2029 $ 80 $ 113 Fixed-rate PSP note payable due through 2031 600 600 Fixed-rate EETC payable due through 2025 & 2027 835 947 Variable-rate notes payable due through 2035 971 514 Less debt issuance costs (15) (15) Total debt 2,471 2,159 Less current portion (a) 289 276 Long-term debt, less current portion $ 2,182 $ 1,883 Weighted-average fixed-interest rate 3.4 % 3.5 % Weighted-average variable-interest rate 6.8 % 5.8 % (a) Excludes finance lease liabilities recognized within Current portion of long-term debt and finance leases in the consolidated balance sheets as of December 31, 2023. Approximately $253 million of the Company's total variable-rate notes payable are effectively fixed via interest rate swaps at December 31, 2023, resulting in an effective weighted-average interest rate for the full debt portfolio of 4.4%. During 2023, the Company incurred debt of $595 million from multiple lenders and sources. New debt includes proceeds of $416 million which is secured by aircraft. Additionally, $179 million was incurred as part of an agreement to finance certain E175 deliveries. Debt from this agreement is reflected as a non-cash transaction within the supplemental disclosures in the consolidated statements of cash flows. The Company made debt payments of $282 million in 2023. Debt Maturity At December 31, 2023, long-term debt principal payments for the next five years and thereafter are as follows (in millions): Total 2024 $ 294 2025 351 2026 307 2027 630 2028 114 Thereafter 790 Total Principal Payments $ 2,486 Bank Lines of Credit Alaska has three credit facilities totaling $626 million as of December 31, 2023. One credit facility is for $150 million, expires in March 2025, and is secured by certain accounts receivable, spare engines, spare parts, and ground service equipment. A second credit facility is for $400 million, expires in June 2026, and is secured by aircraft. Both facilities have variable interest rates based on SOFR plus a specified margin. A third credit facility is for $76 million, expires in June 2024, and is secured by aircraft. Alaska has secured letters of credit against the third facility, but has no plans to borrow using either of the other two facilities. All credit facilities have a requirement to maintain a minimum unrestricted cash and marketable securities balance of $500 million. Alaska was in compliance with this covenant at December 31, 2023.

EMPLOYEE BENEFIT PLANS

EMPLOYEE BENEFIT PLANS	12 Months Ended
	Dec. 31, 2023
Retirement Benefits [Abstract]
EMPLOYEE BENEFIT PLANS	EMPLOYEE BENEFIT PLANS Four qualified defined-benefit plans, one non-qualified defined-benefit plan, and eight defined-contribution retirement plans cover various employee groups of Alaska, Horizon, and McGee Air Services. 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 post-retirement 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 four qualified defined-benefit pension plans are funded as required by the Employee Retirement Income Security Act of 1974. The defined-benefit plan assets consist primarily of marketable equity and fixed-income securities. The work groups covered by qualified defined-benefit pension plans include salaried employees, pilots, clerical, office, passenger service employees, mechanics, and related craft employees. The Company uses a December 31 measurement date for these plans. All plans are closed to new entrants. Weighted average assumptions used to determine benefit obligations: The rates below vary by plan and related work group. 2023 2022 Discount rates 5.14% to 5.16% 5.41% to 5.42% Rate of compensation increases 2.01% to 2.34% 2.01% to 2.35% Weighted average assumptions used to determine net periodic benefit cost: The rates below vary by plan and related work group. 2023 2022 2021 Discount rates 5.41% to 5.42% 2.82% to 2.90% 2.43% to 2.58% Expected return on plan assets 5.00% to 6.50% 3.00% to 5.25% 3.00% to 5.50% Rate of compensation increases 2.01% to 2.35% 2.02% to 2.38% 2.02% to 2.43% The discount rates are determined using current interest rates earned on high-quality, long-term bonds with maturities that correspond with the estimated cash distributions from the pension plans. At December 31, 2023, 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 target and actual asset allocation of the funds in the qualified defined-benefit plans, by asset category, are as follows: Salaried Plan (a) All Other Plans Target 2023 2022 Target 2023 2022 Asset category: Domestic equity securities 2%-12% 7 % 7 % 29%-39% 36 % 35 % Non-U.S. equity securities 0%-8% 3 % 3 % 9%-19% 15 % 15 % Fixed income securities 85%-95% 90 % 90 % 37%-57% 45 % 45 % Real estate 0% — % — % 0%-10% 4 % 5 % Plan assets 100 % 100 % 100 % 100 % (a) As our Salaried Plan is frozen and fully funded, our investment strategies differ significantly from that of our other outstanding plans. Investments are in lower-risk securities, with earnings designed to maintain a fully-funded status. The Company’s investment policy focuses on achieving maximum returns at a reasonable risk for pension assets over a full market cycle. 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. Plan assets invested in common commingled trust funds are fair valued using the net asset values of these funds to determine fair value as allowed using the practical expedient 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 assets by fund category (in millions): 2023 2022 Fair Value Hierarchy Fund type: U.S. equity market fund $ 634 $ 568 2 Non-U.S. equity fund 261 242 2 Credit bond index fund 1,061 1,001 2 Plan assets in common commingled trusts $ 1,956 $ 1,811 Real estate 60 76 (a) Cash equivalents 7 7 1 Total plan assets $ 2,023 $ 1,894 (a) In accordance with Subtopic 820-10, certain investments that are measured at net asset value per share (or its equivalent) have not been classified in the fair value hierarchy. The following table sets forth the status of the qualified defined-benefit pension plans (in millions): 2023 2022 Projected benefit obligation (PBO) Beginning of year $ 2,079 $ 2,758 Service cost 29 46 Interest cost 108 66 Plan amendments (a) — 9 Actuarial (gain)/loss 83 (628) Benefits paid (116) (172) End of year $ 2,183 $ 2,079 Plan assets at fair value Beginning of year $ 1,894 $ 2,695 Actual return on plan assets 245 (629) Benefits paid (116) (172) End of year $ 2,023 $ 1,894 Unfunded status $ (160) $ (185) Percent funded 93 % 91 % (a) In conjunction with the 2022 collective bargaining agreement with ALPA, certain participants had credited service restored for leave periods which were previously ineligible for accrual. The accumulated benefit obligation for the combined qualified defined-benefit pension plans was $2.1 billion and $2.0 billion at December 31, 2023 and 2022. During 2023 actuarial losses increased the benefit obligation primarily due to decreases in discount rates, partially offset by changes in demographic assumptions. Plan assets increased in 2023 driven primarily by positive market returns on the portfolio. The amounts recognized in the consolidated balance sheets (in millions): 2023 2022 Accrued benefit liability-long term $ (245) $ (240) Plan assets-long term (within Other noncurrent assets) 85 55 Total liability recognized $ (160) $ (185) The amounts not yet reflected in net periodic benefit cost and included in AOCL (in millions): 2023 2022 Prior service cost (credit) $ 6 $ 6 Net loss 367 438 Amount recognized in AOCL (pretax) $ 373 $ 444 Defined benefit plans with projected benefit obligations and accumulated benefit obligations exceeding fair value of plan assets are as follows (in millions): 2023 2022 Projected benefit obligation $ 1,403 $ 1,332 Accumulated benefit obligation 1,327 1,267 Fair value of plan assets 1,158 1,092 Net pension expense for the qualified defined-benefit plans included the following components (in millions): 2023 2022 2021 Service cost $ 29 $ 45 $ 52 Interest cost 108 65 56 Expected return on assets (114) (128) (122) Amortization of prior service credit — (1) (1) Recognized actuarial loss 23 8 37 Net pension expense (benefit) $ 46 $ (11) $ 22 Alaska expects to have approximately $30 million in estimated required contributions for its plans in 2024. 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): Total 2024 $ 113 2025 131 2026 139 2027 154 2028 163 2029-2033 854 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 periodic 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, and accumulated benefit obligation are immaterial. The net pension expense in prior year and expected future expense is also immaterial. Post-retirement 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 post-retirement benefit obligation for this subsidy is unfunded. The accumulated post-retirement benefit obligation was $98 million and $89 million at December 31, 2023 and 2022. The net periodic benefit cost was not material in 2023 or 2022. Defined-Contribution Plans The eight 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 $203 million, $160 million and $125 million in 2023, 2022, and 2021. 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 sheets at December 31, 2023 and 2022. 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, 2023 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 $72 million and $69 million, which was recorded net of a prefunded trust account of $10 million and $11 million, and included in long-term other liabilities on the consolidated balance sheets as of December 31, 2023 and December 31, 2022. Employee Incentive-Pay Plans The Company has employee incentive plans that pay employees based on certain financial and operational metrics. These metrics are set and approved annually by the Compensation and Leadership Development Committee of the Board of Directors. The aggregate expense under these plans in 2023, 2022 and 2021 was $200 million, $257 million and $151 million. The incentive plans are summarized below. • Performance-Based Pay (PBP) is a program that rewards the majority of Alaska and Horizon employees. The program is based on various metrics that adjust periodically, including those related to Air Group profitability, safety, guest experience, and sustainability. The program also includes the potential for additional payout if Air Group profitability finishes among the highest in the industry. • The Operational Performance Rewards Program (OPR) entitles the majority of Alaska and Horizon employees to quarterly payouts of up to $450 per person if certain operational and safety objectives are met.

SHAREHOLDER'S EQUITY

SHAREHOLDER'S EQUITY	12 Months Ended
	Dec. 31, 2023
Equity [Abstract]
SHAREHOLDER'S EQUITY	SHAREHOLDERS' EQUITY Common Stock Repurchase In August 2015, the Board of Directors authorized a $1 billion share repurchase program. In March 2020, the Company suspended the share repurchase program as required by the CARES Act. These restrictions ended on October 1, 2022. The Company restarted the share repurchase program in February 2023, pursuant to the existing repurchase program. As of December 31, 2023, the Company has repurchased 11.1 million shares for $688 million under this program. The program has remaining authorization of $312 million. No shares were repurchased in 2022. Share purchase activity (in millions, except share amounts): Twelve Months Ended December 31, 2023 Shares Amount (a) 2015 Repurchase Program—$1 billion 3,520,533 $ 145 (a) Due to the timing difference between trade date and settlement date, certain repurchases had not settled in cash as of December 31, 2023, and may not agree directly to the consolidated statements of cash flows. CARES Act Warrant Issuance As taxpayer protection required under the Payroll Support Program (PSP) under the CARES Act, the Company granted the U.S. government a total of 1,455,437 warrants to purchase ALK common stock in 2020 and 2021. An additional 427,080 warrants were issued in conjunction with a draw on the CARES Act Loan in 2020. These warrants are non-voting, freely transferable, may be settled as net shares or in cash at the Company's option, and have a five-year term. As of December 31, 2023, there are 1,882,517 total warrants outstanding, with a weighted average strike price of 39.06. The value of the warrants was estimated using a Black-Scholes option pricing model. The total fair value of the warrants of $30 million, recorded in stockholders' equity at issuance.

STOCK-BASED COMPENSATION PLANS

STOCK-BASED COMPENSATION PLANS	12 Months Ended
	Dec. 31, 2023
Share-Based Payment Arrangement [Abstract]
STOCK-BASED COMPENSATION PLANS	STOCK-BASED COMPENSATION PLANS 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 table below summarizes the components of total stock-based compensation (in millions): 2023 2022 2021 Stock options $ 2 $ 3 $ 5 Stock awards (a) 39 14 20 Deferred stock awards 1 1 1 Employee stock purchase plan 17 17 18 Stock-based compensation $ 59 $ 35 $ 44 Tax benefit related to stock-based compensation $ 14 $ 9 $ 11 (a) In 2023, the Company, with approval by the Compensation and Leadership Development Committee of the Board of Directors, granted additional stock awards to address equity value forfeited by certain executives due to the compensation limitations of the CARES Act. Unrecognized stock-based compensation for non-vested options and awards and the weighted-average period the expense will be recognized (dollars in millions): Amount Weighted-Average Stock options $ 1 0 Stock awards 26 1.6 Unrecognized stock-based compensation $ 27 1.6 The Company is authorized to issue 20 million shares of common stock under these plans, of which 9 million shares remain available for future grants of either options or stock awards as of December 31, 2023. 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: 2023 2022 2021 Expected volatility 46 % 44 % 43 % Expected term 6 years 6 years 6 years Risk-free interest rate 3.64 % 1.91 % 0.68 % Expected dividend yield — — — Weighted-average grant date fair value per share $ 16.77 $ 23.36 $ 23.66 Estimated fair value of options granted (millions) $ 1 $ 4 $ 4 The expected market price volatility and expected term are based on historical results. 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, 2023: Shares Weighted- Weighted- Aggregate Intrinsic Outstanding, December 31, 2022 1,230,757 $ 61.45 5.6 $ 1 Granted 50,120 58.54 Exercised (24,996) 35.44 Canceled (86,475) 68.95 Forfeited or expired (7,976) 56.37 Outstanding, December 31, 2023 1,161,430 $ 61.36 5.1 $ — Exercisable, December 31, 2023 883,061 $ 62.84 4.5 $ — Vested or expected to vest, December 31, 2023 1,161,430 $ 61.36 5.1 $ — (in millions) 2023 2022 2021 Intrinsic value of option exercises $ — $ — $ 3 Fair value of options vested $ 4 $ 4 $ 4 Cash received from stock option exercises was not material for the year ended December 31, 2023. 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 vesting period. The fair value of the RSUs is based on the stock price on the date of grant. Generally, 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 Weighted-Average Grant Date Fair Value Weighted- Aggregate Non-vested, December 31, 2022 106,760 $ 53.97 2.9 $ 11 Granted 1,245,008 51.99 Vested (389,231) 51.03 Forfeited (93,753) 61.97 Non-vested, December 31, 2023 868,784 $ 51.95 1.7 $ 34 Deferred Stock Awards Deferred Stock Units (DSUs) are awarded to members of the 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 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 1,855,608, 1,292,489 and 1,254,393 shares in 2023, 2022 and 2021 under the ESPP.

OPERATING SEGMENT INFORMATION

OPERATING SEGMENT INFORMATION	12 Months Ended
	Dec. 31, 2023
Segment Reporting [Abstract]
Operating Segment Information	OPERATING SEGMENT INFORMATION Alaska Air Group has two operating airlines—Alaska and Horizon. Each is regulated by the U.S. Department of Transportation’s Federal Aviation Administration. Alaska has CPAs for regional capacity with Horizon and SkyWest, under which Alaska receives all passenger revenue. Under GAAP, operating segments are defined as components of a business for which there is discrete financial information that is regularly assessed by the Chief Operating Decision Maker (CODM) in making resource allocation decisions. Financial performance for the operating airlines and CPAs is managed and reviewed by the Company's CODM as part of three reportable operating segments: • Mainline - includes scheduled air transportation on Alaska's Boeing jet aircraft for passengers and cargo throughout the U.S., and in parts of Canada, Mexico, Costa Rica, Belize, Guatemala, and the Bahamas. • Regional - includes Horizon's and other third-party carriers’ scheduled air transportation for passengers across a shorter distance network within the U.S., Canada, and Mexico under a CPA. This segment includes the actual revenue and expenses associated with regional flying, as well as an allocation of corporate overhead incurred by Air Group on behalf of the regional operations. • Horizon - includes the capacity sold to Alaska under a CPA. Expenses include those typically borne by regional airlines such as crew costs, ownership costs and maintenance costs. The CODM makes resource allocation decisions for these reporting segments based on flight profitability data, aircraft type, route economics and other financial information. The "Consolidating and Other" column reflects parent company activity, McGee Air Services, consolidating entries and other immaterial business units of the company. The “Air Group Adjusted” column represents a non-GAAP measure that is used by the Company CODM to evaluate performance and allocate resources. Adjustments are further explained below in reconciling to consolidated GAAP results. Operating segment information is as follows (in millions): Year Ended December 31, 2023 Mainline Regional Horizon Consolidating & Other (a) Air Group Adjusted (b) Special Items (c) Consolidated Operating Revenue Passenger revenue $ 8,097 $ 1,429 $ — $ — $ 9,526 $ — $ 9,526 CPA revenue — — 374 (374) — — — Mileage Plan other revenue 599 49 — — 648 — 648 Cargo and other revenue 244 — — 8 252 — 252 Total Operating Revenue 8,940 1,478 374 (366) 10,426 — 10,426 Operating Expenses Operating expenses, excluding fuel 5,841 1,121 344 (358) 6,948 443 7,391 Fuel expense 2,264 379 — — 2,643 (2) 2,641 Total Operating Expenses 8,105 1,500 344 (358) 9,591 441 10,032 Non-operating Income (Expense) (15) — (41) 3 (53) (18) (71) Income (Loss) Before Income Tax $ 820 $ (22) $ (11) $ (5) $ 782 $ (459) $ 323 Pretax Margin 7.5 % 3.1 % Year Ended December 31, 2022 Mainline Regional Horizon Consolidating & Other (a) Air Group Adjusted (b) Special Items (c) Consolidated Operating Revenue Passenger revenue $ 7,454 $ 1,354 $ — $ — $ 8,808 $ — $ 8,808 CPA revenue — — 359 (359) — — — Mileage Plan other revenue 538 52 — — 590 — 590 Cargo and other revenue 244 — — 4 248 — 248 Total Operating Revenue 8,236 1,406 359 (355) 9,646 — 9,646 Operating Expenses Operating expenses, excluding fuel 5,216 1,085 383 (356) 6,328 580 6,908 Fuel expense 2,195 397 — — 2,592 76 2,668 Total Operating Expenses 7,411 1,482 383 (356) 8,920 656 9,576 Non-operating Income (Expense) 30 — (22) 1 9 — 9 Income (Loss) Before Income Tax $ 855 $ (76) $ (46) $ 2 $ 735 $ (656) $ 79 Pretax Margin 7.6 % 0.8 % Year Ended December 31, 2021 Mainline Regional Horizon Consolidating & Other (a) Air Group Adjusted (b) Special Items (c) Consolidated Operating Revenue Passenger revenue $ 4,411 $ 1,088 $ — $ — $ 5,499 $ — $ 5,499 CPA revenue — — 406 (406) — — — Mileage Plan other revenue 402 59 — — 461 — 461 Cargo and other revenue 212 — — 4 216 — 216 Total Operating Revenue 5,025 1,147 406 (402) 6,176 — 6,176 Operating Expenses Operating expenses, excluding fuel 4,101 1,096 373 (433) 5,137 (925) 4,212 Fuel expense 1,065 261 — — 1,326 (47) 1,279 Total Operating Expenses 5,166 1,357 373 (433) 6,463 (972) 5,491 Non-operating Income (Expense) (38) — (21) 3 (56) — (56) Income (Loss) Before Income Tax $ (179) $ (210) $ 12 $ 34 $ (343) $ 972 $ 629 Pretax Margin (5.6) % 10.2 % (a) Includes consolidating entries, Air Group parent company, McGee Air Services, and other immaterial business units. (b) The Air Group Adjusted column represents the financial information that is reviewed by management to assess performance of operations and determine capital allocations and excludes certain charges. (c) Includes special items and mark-to-market fuel-hedge accounting adjustments. 2023 2022 2021 Depreciation and amortization: Mainline $ 403 $ 351 $ 323 Horizon 48 64 71 Consolidated $ 451 $ 415 $ 394 Capital expenditures: Mainline $ 1,473 $ 1,544 $ 236 Horizon (a) 200 127 56 Consolidated $ 1,673 $ 1,671 $ 292 Total assets at end of period: Mainline $ 19,937 $ 19,733 Horizon 1,352 1,157 Consolidating & Other (6,676) (6,704) Consolidated $ 14,613 $ 14,186

Earnings Per Share

Earnings Per Share	12 Months Ended
	Dec. 31, 2023
Earnings Per Share [Abstract]
Earnings Per Share [Text Block]	NOTE 15. EARNINGS PER SHARE Basic earnings per share is calculated by dividing net income by the weighted average number of common shares outstanding during the period. Diluted earnings per share is calculated by dividing net income by the weighted average number of common shares outstanding during the period, including potential dilution from the exercise of in-the-money stock options, stock awards, the employee stock purchase plan, and warrants issued under various federal payroll support programs using the treasury stock method. Anti-dilutive common stock equivalents excluded from the calculation of diluted earnings per share were 1.9 million, 1.7 million, and 1.4 million during the years ending December 31, 2023, 2022, and 2021 .

Business Combinations and Asset

Business Combinations and Asset Acquisitions	12 Months Ended
	Dec. 31, 2023
Business Combination and Asset Acquisition [Abstract]
Business Combination Disclosure [Text Block]	NOTE 16. PROPOSED ACQUISITION OF HAWAIIAN HOLDINGS INC. On December 2, 2023, the Company entered into a definitive agreement to acquire Hawaiian Holdings, Inc. (Hawaiian). The Company has agreed to pay Hawaiian's shareholders $18.00 per share, or approximately $1.0 billion, in cash for the outstanding shares of Hawaiian Holdings, Inc. In addition, the Company expects to assume Hawaiian's debt and lease obligations on the date of acquisition. The acquisition is subject to approval by Hawaiian's shareholders and various regulatory bodies, among other customary closing conditions. The shareholder vote is scheduled to take place on February 16, 2024. To date, the financial impacts of the pending acquisition have not been material, and future financial impacts are not yet estimable. The Company currently expects the acquisition will close in 2025, subject to Hawaiian shareholder approval and U.S. antitrust clearance.

GENERAL AND SUMMARY OF SIGNIF_2

GENERAL AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	12 Months Ended
	Dec. 31, 2023
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 (Air Group, or the Company), and its primary subsidiaries, Alaska Airlines, Inc. (Alaska) and Horizon Air Industries, Inc. (Horizon). Our consolidated financial statements also include McGee Air Services, a ground services subsidiary of Alaska. The Company conducts substantially all of its operations through these subsidiaries. All 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 (GAAP) and their preparation requires the use of management’s estimates. Actual results may differ from these estimates. Certain rows, columns, figures, or percentages may not recalculate due to rounding.
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 $14 million and $9 million at December 31, 2023 and 2022, 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's restricted cash balances are not material and are classified as Other noncurrent assets. Restricted cash balances are primarily used to guarantee various letters of credit, self-insurance programs, or other contractual rights. They consist of highly liquid securities with original maturities of three months or less. They are carried at cost, which approximates fair value.
Marketable 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 are reflected in accumulated other comprehensive income (loss). The Company evaluates the investment portfolio on a quarterly basis for expected credit losses. The Company uses a systematic methodology that groups assets by relevant market sector, and considers available quantitative and qualitative evidence in evaluating potential allowances for credit losses. If the cost of an investment exceeds its fair value, management evaluates, among other factors, general market and industry conditions, credit quality of debt instrument issuers, the duration and extent to which the fair value is less than cost, the Company's intent and ability to hold, or plans to sell, the investment. Once a decline in fair value is determined to be the result of an expected credit loss, an allowance is recorded to Other—net in the consolidated statements of operations.
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 expendable inventories was $60 million and $55 million at December 31, 2023 and 2022. Removals from the reserve in 2023 were immaterial. Inventory and supplies - net also includes fuel inventory of $31 million and $38 million at December 31, 2023 and 2022. 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: Estimated Useful Life Estimated Salvage Value Aircraft and other flight equipment: B737 and E175 aircraft 20 to 25 years 10% Buildings 25 to 40 years 10% Minor building and land improvements 10 years —% Capitalized leases and leasehold improvements Generally shorter of lease term or —% Computer hardware and software 3 to 10 years —% Other furniture and equipment 5 to 10 years —% Near the end of an asset's estimated useful life, management updates the salvage value estimates based on current market conditions and expected use of the asset. Repairable and rotable aircraft parts are included in Aircraft and other flight equipment, and are depreciated over the associated fleet life. Capitalized interest, 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. 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 at which identifiable cash flows are largely independent of the cash flows of other groups of assets and liabilities, which is generally the fleet level. 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 . For these purposes, the fair value is estimated using a combination of Level 2 inputs, including published market value estimates for the assets being assessed, and Level 3 inputs, including Company-specific and asset-specific indicators.
Goodwill	Goodwill
Intangible Assets	Intangible Assets Intangible assets are comprised primarily of indefinite-lived airport slots recorded in conjunction with the acquisition of Virgin America. Indefinite-lived intangibles were recorded at fair value upon acquisition and are not amortized, but are tested at least annually for impairment using a similar methodology to goodwill, as described above.
Aircraft Maintenance Deposits	Aircraft Maintenance Deposits Certain Airbus leases include contractually required maintenance deposit payments to the lessor, which collateralize the lessor for future maintenance events should the Company not perform required maintenance. Most of the lease agreements provide that maintenance deposits are reimbursable upon completion of the major maintenance event in an amount equal to the lesser of (i) the amount qualified for reimbursement from maintenance deposits held by the lessor associated with the specific major maintenance event or (ii) the qualifying costs related to the specific major maintenance event. The Company establishes accounting maintenance deposits as assets on the balance sheet using estimates of the anticipated timing and cost of the specific major maintenance events, such that the accounting deposits do not exceed the amount qualified for reimbursement. Aircraft maintenance deposits recorded on the consolidated balance sheets were $70 million and $140 million as of December 31, 2023 and December 31, 2022. As of December 31, 2023, all maintenance deposits are presented within Other current assets on the consolidated balance sheets.
Leased Aircraft Return Costs [Policy Text Block]	Leased Aircraft Return Costs Costs to return leased aircraft are accrued when the costs are probable and reasonably estimable, usually over the twelve months prior to the lease return, unless a determination is made to remove the leased asset from operation. If the leased aircraft is removed from the operating fleet, the estimated cost to return is accrued at the time of removal. If a leased aircraft has a known early retirement date in the future, the estimated cost to return is accrued through the retirement date. 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 may not be known with certainty until lease termination. As leased aircraft are returned, payments made reduce the outstanding lease return liability. As of December 31, 2023, the total outstanding liability is $112 million and is included in Other accrued liabilities, compared to $186 million included in Other accrued liabilities and $91 million included in Other liabilities as of December 31, 2022.
Advertising Cost, Policy, Expensed Advertising Cost [Policy Text Block]	Advertising Expenses
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 exposure to these risks, the Company has entered 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 are recognized in AOCL or in the consolidated statements of operations, depending on the nature of the instrument. Cash flows related to these derivative instruments are classified as operating cash flows within the consolidated statements of cash flows. The Company does not apply hedge accounting to its derivative fuel hedge contracts, nor does it hold or issue them for trading purposes. For cash flow hedges related to 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]
Income Tax, Policy [Policy Text Block]	Income Taxes The Company uses the asset and liability approach for accounting for 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. As of December 31, 2023, there is a partial valuation allowance against net deferred tax assets. The Company accounts for unrecognized tax benefits in accordance with the applicable accounting standards.
Share-based Compensation, Option and Incentive Plans Policy [Policy Text Block]	Stock-Based Compensation Accounting standards require companies to recognize expense over the service period based on the fair value of stock options and other equity-based compensation issued to employees estimated 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.
New Accounting Pronouncements, Policy [Policy Text Block]	Recent Accounting Pronouncements In November 2023, the FASB issued ASU 2023-07, Segment Reporting (Topic 280), which requires public entities to disclose information about their reportable segments’ significant expenses and other segment items on an interim and annual basis. ASU 2023-07 is effective for fiscal years beginning after December 15, 2023, and for interim periods within fiscal years beginning after December 15, 2024, with early adoption permitted. The Company is currently evaluating the impact of adopting ASU 2023-07. In December 2023, the FASB issued ASU 2023-09, Income Taxes (Topic 740), which requires public entities to provide disclosure of specific categories in the rate reconciliation, as well as disclosure of income taxes paid disaggregated by jurisdiction on an annual basis. ASU 2023-09 is effective for fiscal years beginning after December 15, 2024, with early adoption permitted. The Company is currently evaluating the impact of adopting ASU 2023-09.
Receivable	Receivables - net Receivables primarily consist of amounts due from credit card processors for the sale of passenger tickets, from the Company's affinity card partner for the purchase of miles under our loyalty program, and from taxing authorities for certain tax receivables. Given the nature of these receivables, reserves are immaterial to the overall balance. In 2023, certain A321neos were sold to a third-party with full payment for the aircraft occurring in January 2024. The balance owed to Alaska as of December 31, 2023 for these transactions was classified within Receivables - net.
Maintenance Cost, Policy	Airframe and Engine Maintenance Expense Maintenance and repairs on our aircraft, other than engine maintenance on certain 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 B737-800, B737-900ER, and E175 engines are covered under power-by-the-hour agreements with third parties, whereby the Company pays a determinable amount, and transfers risk, to a third party. For these agreements, the Company expenses the contract amounts based on engine usage.

GENERAL AND SUMMARY OF SIGNIF_3

GENERAL AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)	12 Months Ended
	Dec. 31, 2023
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: Estimated Useful Life Estimated Salvage Value Aircraft and other flight equipment: B737 and E175 aircraft 20 to 25 years 10% Buildings 25 to 40 years 10% Minor building and land improvements 10 years —% Capitalized leases and leasehold improvements Generally shorter of lease term or —% Computer hardware and software 3 to 10 years —% Other furniture and equipment 5 to 10 years —%

REVENUE FROM CONTRACTS WITH C_2

REVENUE FROM CONTRACTS WITH CUSTOMERS (Tables)	12 Months Ended
	Dec. 31, 2023
Revenue from Contracts with Customer [Abstract]
Disaggregation of Revenue [Table Text Block]	Passenger revenue recognized in the consolidated statements of operations (in millions): Twelve Months Ended December 31, 2023 2022 2021 Passenger ticket revenue, net of taxes and fees $ 8,016 $ 7,430 $ 4,533 Passenger ancillary revenue 476 447 327 Mileage Plan passenger revenue 1,034 931 639 Total Passenger revenue $ 9,526 $ 8,808 $ 5,499 Mileage Plan revenue included in the consolidated statements of operations (in millions): Twelve Months Ended December 31, 2023 2022 2021 Passenger revenue $ 1,034 $ 931 $ 639 Mileage Plan other revenue 648 590 461 Total Mileage Plan revenue $ 1,682 $ 1,521 $ 1,100 Cargo and other revenue included in the consolidated statements of operations (in millions): Twelve Months Ended December 31, 2023 2022 2021 Cargo revenue $ 128 $ 133 $ 124 Other revenue 124 115 92 Total Cargo and other revenue $ 252 $ 248 $ 216
Contract with Customer, Asset and Liability [Table Text Block]	The table below presents a roll forward of the total frequent flyer liability (in millions): Twelve Months Ended December 31, 2023 2022 Total Deferred Revenue balance at January 1 $ 2,497 $ 2,358 Travel miles and companion certificate redemption - Passenger revenue (974) (878) Miles redeemed on partner airlines - Other revenue (117) (65) Increase in liability for mileage credits issued 1,197 1,082 Total Deferred Revenue balance at December 31 $ 2,603 $ 2,497

DERIVATIVE INSTRUMENTS (Tables)

DERIVATIVE INSTRUMENTS (Tables)	12 Months Ended
	Dec. 31, 2023
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): 2023 2022 Fuel hedge contracts (not designated as hedges) Other current assets $ 10 $ 33 Other assets 1 11 Interest rate swaps (designated as hedges) Other current assets 6 8 Other noncurrent assets 2 7 (Losses)/gains in accumulated other comprehensive loss (AOCL) (7) 23
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): 2023 2022 2021 Fuel hedge contracts (not designated as hedges) (Losses)/gains recognized in Aircraft fuel $ (62) $ 93 $ 104 Interest rate swaps (designated as hedges) (Losses)/gains recognized in other comprehensive income (OCI) (7) 23 17

FAIR VALUE MEASUREMENTS (Tables

FAIR VALUE MEASUREMENTS (Tables)	12 Months Ended
	Dec. 31, 2023
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, 2023 December 31, 2022 Level 1 Level 2 Total Level 1 Level 2 Total Assets Marketable securities U.S. government and agency securities $ 387 $ — $ 387 $ 505 $ — $ 505 Equity mutual funds 5 — 5 5 — 5 Foreign government bonds — 10 10 — 25 25 Asset-backed securities — 192 192 — 261 261 Mortgage-backed securities — 115 115 — 196 196 Corporate notes and bonds — 763 763 — 1,025 1,025 Municipal securities — 38 38 — 62 62 Total Marketable securities 392 1,118 1,510 510 1,569 2,079 Derivative instruments Fuel hedge contracts - call options — 11 11 — 44 44 Interest rate swap agreements — 8 8 — 15 15 Total Assets $ 392 $ 1,137 $ 1,529 $ 510 $ 1,628 $ 2,138 Fixed-rate debt on the consolidated balance sheet and the estimated fair value of long-term fixed-rate debt (in millions): December 31, 2023 December 31, 2022 Fixed-rate debt $ 1,515 $ 1,660 Estimated fair value $ 1,382 $ 1,473 Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis Certain assets and liabilities are recognized or disclosed at fair value on a nonrecurring basis, including property, plant and equipment, operating lease assets, goodwill, and intangible assets. These assets are subject to fair valuation when there is evidence of impairment. Refer to Note 2 for discussion regarding impairment charges recorded in the year.
Schedule of Realized Gain (Loss) [Table Text Block]	Proceeds from sales of marketable securities were $1.2 billion, $2.3 billion, and $3.6 billion in 2023, 2022, and 2021.
Schedule of Debt Investment Maturities [Table Text Block]	Maturities for marketable securities (in millions): December 31, 2023 Cost Basis Fair Value Due in one year or less $ 372 $ 366 Due after one year through five years 1,126 1,091 Due after five years through nine years 36 33 Due after 10 years 17 15 No maturity date 4 5 Total $ 1,555 $ 1,510

LONG-TERM DEBT (Tables)

LONG-TERM DEBT (Tables)	12 Months Ended
	Dec. 31, 2023
Debt Disclosure [Abstract]
Schedule of Long-term Debt Instruments [Table Text Block]	Long-term debt obligations on the consolidated balance sheet (in millions): 2023 2022 Fixed-rate notes payable due through 2029 $ 80 $ 113 Fixed-rate PSP note payable due through 2031 600 600 Fixed-rate EETC payable due through 2025 & 2027 835 947 Variable-rate notes payable due through 2035 971 514 Less debt issuance costs (15) (15) Total debt 2,471 2,159 Less current portion (a) 289 276 Long-term debt, less current portion $ 2,182 $ 1,883 Weighted-average fixed-interest rate 3.4 % 3.5 % Weighted-average variable-interest rate 6.8 % 5.8 %
Schedule of Maturities of Long-term Debt [Table Text Block]	At December 31, 2023, long-term debt principal payments for the next five years and thereafter are as follows (in millions): Total 2024 $ 294 2025 351 2026 307 2027 630 2028 114 Thereafter 790 Total Principal Payments $ 2,486

Leases, Codification Topic 842

Leases, Codification Topic 842 (Tables)	12 Months Ended
	Dec. 31, 2023
Leases [Abstract]
Schedule of Lease Assets	Operating lease assets balance by asset class was as follows (in millions): December 31, 2023 December 31, 2022 Aircraft $ 468 $ 701 CPA Aircraft 622 683 Airport and terminal facilities 29 21 Corporate real estate and other 76 66 Total Operating Lease Assets $ 1,195 $ 1,471
Lease, Cost	The impact of leases, including variable lease cost, was as follows (in millions): Classification 2023 2022 2021 Expense Aircraft (a) Aircraft rent $ 100 $ 191 $ 174 CPA Aircraft Aircraft rent 108 100 80 Airport and terminal facilities Landing fees and other rentals 451 384 379 Corporate real estate and other Landing fees and other rentals 31 33 21 Total lease expense $ 690 $ 708 $ 654 Revenue Lease revenue Cargo and other revenue (15) (15) (16) Net lease impact $ 675 $ 693 $ 638 (a) Aircraft lease expense excludes the portion of aircraft rent that was accelerated due to the fleet transition and recorded to Special items - fleet transition and other, as well as interest expense associated with certain A321neo finance leases recorded to Special items - net non-operating within the consolidated statements of operations. Refer to Note 2 to the consolidated financial statements for additional information.
Lessee, Operating Lease, Liability, Maturity	Future minimum lease payments under non-cancellable leases as of December 31, 2023 (in millions): Aircraft (a) CPA Aircraft Airport and Terminal Facilities Corporate Real Estate and Other 2024 $ 162 $ 112 $ 5 $ 10 2025 72 112 6 9 2026 75 112 6 9 2027 71 112 5 8 2028 64 110 5 7 Thereafter 306 276 9 112 Total Lease Payments (b) $ 750 $ 834 $ 36 $ 155 Less: Imputed interest (145) (191) (6) (74) Total $ 605 $ 643 $ 30 $ 81 (a) Future minimum lease payments include payments for aircraft operated under operating leases and aircraft removed from operating service which remain under operating and finance leases, as we have remaining cash obligations under existing terms. (b) Future minimum lease payments in the table reflect incentive credits related to leased B737-9 aircraft. As a result, the operating lease liabilities presented on the consolidated balance sheet will not agree to this table.
Weighted Average Lease Assumptions	The weighted average IBR and weighted average remaining lease term (in years) for all asset classes were as follows at December 31, 2023. Weighted Average IBR Weighted Average Remaining Lease Term Aircraft 5.5 % 9.3 CPA Aircraft 7.0 % 7.8 Airport and terminal facilities 5.3 % 6.7 Corporate real estate and other 5.4 % 26.6

INCOME TAXES (Tables)

INCOME TAXES (Tables)	12 Months Ended
	Dec. 31, 2023
Income Tax Disclosure [Abstract]
Schedule of Deferred Tax Assets and Liabilities [Table Text Block]	Deferred tax (assets) and liabilities comprise the following (in millions): 2023 2022 Excess of tax over book depreciation $ 1,605 $ 1,312 Intangibles - net 16 17 Operating lease assets 292 356 Other - net 3 49 Deferred tax liabilities 1,916 1,734 Mileage Plan (455) (436) Inventory obsolescence (23) (21) Employee benefits (159) (145) Net operating losses (166) (28) Operating lease liabilities (329) (392) Leasehold maintenance (28) (67) Other - net (77) (88) Deferred tax assets (1,237) (1,177) Valuation allowance 16 17 Net deferred tax liabilities $ 695 $ 574
Schedule of Components of Income Tax Expense (Benefit) [Table Text Block]	The components of income tax expense are as follows (in millions): 2023 2022 2021 Current income tax (benefit) expense: Federal $ (3) $ (11) $ 40 State (4) (3) 16 Total current income tax (benefit) expense (7) (14) 56 Deferred income tax expense: Federal 82 32 80 State 13 3 15 Total deferred income tax expense 95 35 95 Income tax expense $ 88 $ 21 $ 151
Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]	2023 2022 2021 Income before income tax $ 323 $ 79 $ 629 Expected tax expense 68 17 132 Nondeductible expenses 14 11 10 State income tax expense 17 5 20 Tax law changes — — (14) State income sourcing (5) (2) — Valuation allowance (1) (4) 1 Tax credits (3) (5) (2) Uncertain tax positions (5) (1) 3 Other - net 3 — 1 Actual tax expense $ 88 $ 21 $ 151 Effective tax rate (a) 27.1 % 26.2 % 24.0 %
Summary of Income Tax Contingencies [Table Text Block]	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 2020 to 2022 Alaska 2018 to 2022 California 2007 to 2022 Oregon 2015 to 2022 Certain tax years are open to the extent of net operating loss carryforwards. Changes in the liability for gross unrecognized tax benefits during 2023, 2022 and 2021 are as follows (in millions): 2023 2022 2021 Balance at January 1 $ 21 $ 41 $ 35 Additions related to prior years — — 3 Releases related to prior years — (1) — Additions related to current year activity 9 1 3 Releases due to settlements (3) (20) — Releases due to lapse of statute of limitations (2) — — Balance at December 31 $ 25 $ 21 $ 41

EMPLOYEE BENEFIT PLANS (Tables)

EMPLOYEE BENEFIT PLANS (Tables)	12 Months Ended
	Dec. 31, 2023
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Plan with Accumulated Benefit Obligation in Excess of Plan Assets	Defined benefit plans with projected benefit obligations and accumulated benefit obligations exceeding fair value of plan assets are as follows (in millions): 2023 2022 Projected benefit obligation $ 1,403 $ 1,332 Accumulated benefit obligation 1,327 1,267 Fair value of plan assets 1,158 1,092
Defined Benefit Plan, Plan with Projected Benefit Obligation in Excess of Plan Assets
Qualified Defined Benefit [Member]
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: The rates below vary by plan and related work group. 2023 2022 Discount rates 5.14% to 5.16% 5.41% to 5.42% Rate of compensation increases 2.01% to 2.34% 2.01% to 2.35% Weighted average assumptions used to determine net periodic benefit cost: The rates below vary by plan and related work group. 2023 2022 2021 Discount rates 5.41% to 5.42% 2.82% to 2.90% 2.43% to 2.58% Expected return on plan assets 5.00% to 6.50% 3.00% to 5.25% 3.00% to 5.50% Rate of compensation increases 2.01% to 2.35% 2.02% to 2.38% 2.02% to 2.43%
Schedule of Allocation of Plan Assets [Table Text Block]	The target and actual asset allocation of the funds in the qualified defined-benefit plans, by asset category, are as follows: Salaried Plan (a) All Other Plans Target 2023 2022 Target 2023 2022 Asset category: Domestic equity securities 2%-12% 7 % 7 % 29%-39% 36 % 35 % Non-U.S. equity securities 0%-8% 3 % 3 % 9%-19% 15 % 15 % Fixed income securities 85%-95% 90 % 90 % 37%-57% 45 % 45 % Real estate 0% — % — % 0%-10% 4 % 5 % Plan assets 100 % 100 % 100 % 100 % (a) As our Salaried Plan is frozen and fully funded, our investment strategies differ significantly from that of our other outstanding plans. Investments are in lower-risk securities, with earnings designed to maintain a fully-funded status. Plan assets by fund category (in millions): 2023 2022 Fair Value Hierarchy Fund type: U.S. equity market fund $ 634 $ 568 2 Non-U.S. equity fund 261 242 2 Credit bond index fund 1,061 1,001 2 Plan assets in common commingled trusts $ 1,956 $ 1,811 Real estate 60 76 (a) Cash equivalents 7 7 1 Total plan assets $ 2,023 $ 1,894
Schedule of Net Funded Status [Table Text Block]	The following table sets forth the status of the qualified defined-benefit pension plans (in millions): 2023 2022 Projected benefit obligation (PBO) Beginning of year $ 2,079 $ 2,758 Service cost 29 46 Interest cost 108 66 Plan amendments (a) — 9 Actuarial (gain)/loss 83 (628) Benefits paid (116) (172) End of year $ 2,183 $ 2,079 Plan assets at fair value Beginning of year $ 1,894 $ 2,695 Actual return on plan assets 245 (629) Benefits paid (116) (172) End of year $ 2,023 $ 1,894 Unfunded status $ (160) $ (185) Percent funded 93 % 91 %
Schedule of Amounts Recognized in Balance Sheet [Table Text Block]	The amounts recognized in the consolidated balance sheets (in millions): 2023 2022 Accrued benefit liability-long term $ (245) $ (240) Plan assets-long term (within Other noncurrent assets) 85 55 Total liability recognized $ (160) $ (185) The amounts not yet reflected in net periodic benefit cost and included in AOCL (in millions): 2023 2022 Prior service cost (credit) $ 6 $ 6 Net loss 367 438 Amount recognized in AOCL (pretax) $ 373 $ 444
Schedule of Net Benefit Costs [Table Text Block]	Net pension expense for the qualified defined-benefit plans included the following components (in millions): 2023 2022 2021 Service cost $ 29 $ 45 $ 52 Interest cost 108 65 56 Expected return on assets (114) (128) (122) Amortization of prior service credit — (1) (1) Recognized actuarial loss 23 8 37 Net pension expense (benefit) $ 46 $ (11) $ 22
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): Total 2024 $ 113 2025 131 2026 139 2027 154 2028 163 2029-2033 854

COMMITMENTS AND CONTINGENCIES C

COMMITMENTS AND CONTINGENCIES COMMITMENTS AND CONTINGENCIES (Tables)	12 Months Ended
	Dec. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Schedule of Future Minimum Rental Payments for Operating Leases and Unrecorded Unconditional Purchase Obligtaions [Table Text Block]	Future minimum payments for commitments as of December 31, 2023 (in millions): Aircraft-Related Commitments (a) Capacity Purchase Agreements and Other Obligations (b) 2024 $ 1,252 $ 235 2025 1,366 230 2026 1,097 224 2027 600 220 2028 151 223 Thereafter 716 515 Total $ 5,182 $ 1,647

SHAREHOLDER'S EQUITY (Tables)

SHAREHOLDER'S EQUITY (Tables)	12 Months Ended
	Dec. 31, 2023
Equity [Abstract]
Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block]	A roll forward of the amounts included in accumulated other comprehensive loss is shown below for the twelve months ended December 31, 2023, 2022, and 2021: Marketable Securities Employee Benefit Plan Interest Rate Derivatives Tax Effect Total Balance at December 31, 2020 $ 30 $ (659) $ (25) $ 160 $ (494) Reclassifications into earnings (6) 33 — (6) 21 Change in value (29) 294 17 (71) 211 Balance at December 31, 2021 $ (5) $ (332) $ (8) $ 83 $ (262) Reclassifications into earnings 9 3 — (4) 8 Change in value (108) (92) 23 43 (134) Balance at December 31, 2022 $ (104) $ (421) $ 15 $ 122 $ (388) Reclassifications into earnings 13 19 — (7) 25 Change in value 45 44 (7) (18) 64 Balance at December 31, 2023 $ (46) $ (358) $ 8 $ 97 $ (299)

ACCUMULATED OTHER COMPREHENSIVE

ACCUMULATED OTHER COMPREHENSIVE LOSS (Tables)	12 Months Ended
	Dec. 31, 2023
Equity [Abstract]
Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block]	A roll forward of the amounts included in accumulated other comprehensive loss is shown below for the twelve months ended December 31, 2023, 2022, and 2021: Marketable Securities Employee Benefit Plan Interest Rate Derivatives Tax Effect Total Balance at December 31, 2020 $ 30 $ (659) $ (25) $ 160 $ (494) Reclassifications into earnings (6) 33 — (6) 21 Change in value (29) 294 17 (71) 211 Balance at December 31, 2021 $ (5) $ (332) $ (8) $ 83 $ (262) Reclassifications into earnings 9 3 — (4) 8 Change in value (108) (92) 23 43 (134) Balance at December 31, 2022 $ (104) $ (421) $ 15 $ 122 $ (388) Reclassifications into earnings 13 19 — (7) 25 Change in value 45 44 (7) (18) 64 Balance at December 31, 2023 $ (46) $ (358) $ 8 $ 97 $ (299)

STOCK-BASED COMPENSATION PLANS

STOCK-BASED COMPENSATION PLANS (Tables)	12 Months Ended
	Dec. 31, 2023
Share-Based Payment Arrangement [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): 2023 2022 2021 Stock options $ 2 $ 3 $ 5 Stock awards (a) 39 14 20 Deferred stock awards 1 1 1 Employee stock purchase plan 17 17 18 Stock-based compensation $ 59 $ 35 $ 44 Tax benefit related to stock-based compensation $ 14 $ 9 $ 11
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 (dollars in millions): Amount Weighted-Average Stock options $ 1 0 Stock awards 26 1.6 Unrecognized stock-based compensation $ 27 1.6
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: 2023 2022 2021 Expected volatility 46 % 44 % 43 % Expected term 6 years 6 years 6 years Risk-free interest rate 3.64 % 1.91 % 0.68 % Expected dividend yield — — — Weighted-average grant date fair value per share $ 16.77 $ 23.36 $ 23.66 Estimated fair value of options granted (millions) $ 1 $ 4 $ 4
Share-based Compensation, Stock Options, Activity [Table Text Block]	The tables below summarize stock option activity for the year ended December 31, 2023: Shares Weighted- Weighted- Aggregate Intrinsic Outstanding, December 31, 2022 1,230,757 $ 61.45 5.6 $ 1 Granted 50,120 58.54 Exercised (24,996) 35.44 Canceled (86,475) 68.95 Forfeited or expired (7,976) 56.37 Outstanding, December 31, 2023 1,161,430 $ 61.36 5.1 $ — Exercisable, December 31, 2023 883,061 $ 62.84 4.5 $ — Vested or expected to vest, December 31, 2023 1,161,430 $ 61.36 5.1 $ — (in millions) 2023 2022 2021 Intrinsic value of option exercises $ — $ — $ 3 Fair value of options vested $ 4 $ 4 $ 4
Schedule of Share-based Compensation, Restricted Stock Units Award Activity [Table Text Block]	The following table summarizes information about outstanding stock awards: Number Weighted-Average Grant Date Fair Value Weighted- Aggregate Non-vested, December 31, 2022 106,760 $ 53.97 2.9 $ 11 Granted 1,245,008 51.99 Vested (389,231) 51.03 Forfeited (93,753) 61.97 Non-vested, December 31, 2023 868,784 $ 51.95 1.7 $ 34

OPERATING SEGMENT INFORMATION (

OPERATING SEGMENT INFORMATION (Tables)	12 Months Ended
	Dec. 31, 2023
Segment Reporting, Asset Reconciling Item [Line Items]
Schedule of Segment Reporting Information, by Segment	Operating segment information is as follows (in millions): Year Ended December 31, 2023 Mainline Regional Horizon Consolidating & Other (a) Air Group Adjusted (b) Special Items (c) Consolidated Operating Revenue Passenger revenue $ 8,097 $ 1,429 $ — $ — $ 9,526 $ — $ 9,526 CPA revenue — — 374 (374) — — — Mileage Plan other revenue 599 49 — — 648 — 648 Cargo and other revenue 244 — — 8 252 — 252 Total Operating Revenue 8,940 1,478 374 (366) 10,426 — 10,426 Operating Expenses Operating expenses, excluding fuel 5,841 1,121 344 (358) 6,948 443 7,391 Fuel expense 2,264 379 — — 2,643 (2) 2,641 Total Operating Expenses 8,105 1,500 344 (358) 9,591 441 10,032 Non-operating Income (Expense) (15) — (41) 3 (53) (18) (71) Income (Loss) Before Income Tax $ 820 $ (22) $ (11) $ (5) $ 782 $ (459) $ 323 Pretax Margin 7.5 % 3.1 % Year Ended December 31, 2022 Mainline Regional Horizon Consolidating & Other (a) Air Group Adjusted (b) Special Items (c) Consolidated Operating Revenue Passenger revenue $ 7,454 $ 1,354 $ — $ — $ 8,808 $ — $ 8,808 CPA revenue — — 359 (359) — — — Mileage Plan other revenue 538 52 — — 590 — 590 Cargo and other revenue 244 — — 4 248 — 248 Total Operating Revenue 8,236 1,406 359 (355) 9,646 — 9,646 Operating Expenses Operating expenses, excluding fuel 5,216 1,085 383 (356) 6,328 580 6,908 Fuel expense 2,195 397 — — 2,592 76 2,668 Total Operating Expenses 7,411 1,482 383 (356) 8,920 656 9,576 Non-operating Income (Expense) 30 — (22) 1 9 — 9 Income (Loss) Before Income Tax $ 855 $ (76) $ (46) $ 2 $ 735 $ (656) $ 79 Pretax Margin 7.6 % 0.8 % Year Ended December 31, 2021 Mainline Regional Horizon Consolidating & Other (a) Air Group Adjusted (b) Special Items (c) Consolidated Operating Revenue Passenger revenue $ 4,411 $ 1,088 $ — $ — $ 5,499 $ — $ 5,499 CPA revenue — — 406 (406) — — — Mileage Plan other revenue 402 59 — — 461 — 461 Cargo and other revenue 212 — — 4 216 — 216 Total Operating Revenue 5,025 1,147 406 (402) 6,176 — 6,176 Operating Expenses Operating expenses, excluding fuel 4,101 1,096 373 (433) 5,137 (925) 4,212 Fuel expense 1,065 261 — — 1,326 (47) 1,279 Total Operating Expenses 5,166 1,357 373 (433) 6,463 (972) 5,491 Non-operating Income (Expense) (38) — (21) 3 (56) — (56) Income (Loss) Before Income Tax $ (179) $ (210) $ 12 $ 34 $ (343) $ 972 $ 629 Pretax Margin (5.6) % 10.2 % (a) Includes consolidating entries, Air Group parent company, McGee Air Services, and other immaterial business units. (b) The Air Group Adjusted column represents the financial information that is reviewed by management to assess performance of operations and determine capital allocations and excludes certain charges. (c) Includes special items and mark-to-market fuel-hedge accounting adjustments. 2023 2022 2021 Depreciation and amortization: Mainline $ 403 $ 351 $ 323 Horizon 48 64 71 Consolidated $ 451 $ 415 $ 394 Capital expenditures: Mainline $ 1,473 $ 1,544 $ 236 Horizon (a) 200 127 56 Consolidated $ 1,673 $ 1,671 $ 292 Total assets at end of period: Mainline $ 19,937 $ 19,733 Horizon 1,352 1,157 Consolidating & Other (6,676) (6,704) Consolidated $ 14,613 $ 14,186

Earnings Per Share (Tables)

Earnings Per Share (Tables) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	1,900	1,700	1,400
Net Income	$ 235	$ 58	$ 478
Basic	127,375	126,657	125,063
Incremental Common Shares Attributable to Dilutive Effect of Share-Based Payment Arrangements	1,333	1,242	1,712
Diluted	128,708	127,899	126,775
Basic earnings per share	$ 1.84	$ 0.46	$ 3.82
Diluted earnings per share	$ 1.83	$ 0.45	$ 3.77

GENERAL AND SUMMARY OF SIGNIF_4

GENERAL AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - CASH AND CASH EQUIVALENTS (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Accounting Policies [Abstract]
Negative cash balance	$ 14	$ 9

GENERAL AND SUMMARY OF SIGNIF_5

GENERAL AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - INVENTORIES AND SUPPLIES - NET (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Accounting Policies [Abstract]
Allowance for all non-surplus expendable inventories	$ 60	$ 55
Fuel inventory	$ 31	$ 38

GENERAL AND SUMMARY OF SIGNIF_6

GENERAL AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - PROPERTY, EQUIPMENT AND DEPRECIATION (Details)	Dec. 31, 2023
Buildings [Member]
Property, Plant and Equipment [Line Items]
Property, Plant, and Equipment, Salvage Value, Percentage	10%
Buildings [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	25 years
Buildings [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	40 years
Minor building and land improvements [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	10 years
Property, Plant, and Equipment, Salvage Value, Percentage	0%
Leaseholds and Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, Plant, and Equipment, Salvage Value, Percentage	0%
Computer hardware and software [Member]
Property, Plant and Equipment [Line Items]
Property, Plant, and Equipment, Salvage Value, Percentage	0%
Computer hardware and software [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Computer hardware and software [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	10 years
Other furniture and equipment [Member]
Property, Plant and Equipment [Line Items]
Property, Plant, and Equipment, Salvage Value, Percentage	0%
Other furniture and equipment [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	5 years
Other furniture and equipment [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	10 years
B737-800 | Aircraft [Member]
Property, Plant and Equipment [Line Items]
Property, Plant, and Equipment, Salvage Value, Percentage	10%
B737-800 | Aircraft [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	20 years
B737-800 | Aircraft [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	25 years

GENERAL AND SUMMARY OF SIGNIF_7

GENERAL AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - ADVERTISING EXPENSES (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Accounting Policies [Abstract]
Advertising Expense	$ 78	$ 85	$ 63

GENERAL AND SUMMARY OF SIGNIF_8

GENERAL AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES GENERAL AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - STOCK-BASED COMPENSATION (Details)	12 Months Ended
	Dec. 31, 2023
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%

GENERAL AND SUMMARY OF SIGNIF_9

GENERAL AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - MAINTENANCE DEPOSITS (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Accounting Policies [Abstract]
Aircraft Maintenance Deposits	$ 70	$ 140
Lease Return Provision, Current	$ (112)	(186)
Lease Return Provision, Non-Current		$ (91)

GENERAL AND SUMMARY OF SIGNI_10

GENERAL AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - LEASE RETURN PROVISION (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Accounting Policies [Abstract]
Lease Return Provision, Current	$ (112)	$ (186)
Lease Return Provision, Non-Current		$ (91)

FLEET TRANSITION (Details)

FLEET TRANSITION (Details) $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($) aircraft	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Impaired Long-Lived Assets Held and Used [Line Items]
Special Items - Impairment charges and other | $	$ 392	$ 496	$ (1)
Finance leased asset, Number of units | aircraft	1
Fleet transition - impairment
Impaired Long-Lived Assets Held and Used [Line Items]
Special Items - Impairment charges and other | $	$ 268	70
Other fleet transition costs
Impaired Long-Lived Assets Held and Used [Line Items]
Special Items - Impairment charges and other | $	124	$ 426
A321neo [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Finance Lease, Impairment Loss | $	$ 278
Number of Aircraft Operated | aircraft	10
A321neo [Member] | Other Current Assets [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Number of Aircraft Operated | aircraft	2
A321neo [Member] | Accounts Receivable [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Number of Aircraft Operated | aircraft	2

COVID-19 PANDEMIC NARRATIVE (De

COVID-19 PANDEMIC NARRATIVE (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended			21 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2021
Concentration Risk [Line Items]
Restructuring Charges	$ 0	$ 0	$ (10)
Special Items - Impairment charges and other	392	$ 496	(1)
Line of credit facility, borrowing capacity	$ 626
Class of Warrant or Right, Number of Securities Called by Warrants or Rights	1,455,437
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 39.06
Adjustments to Additional Paid in Capital, Warrant Issued			$ 16
US Treasury CARES Act Loan
Concentration Risk [Line Items]
Adjustments to Additional Paid in Capital, Warrant Issued				$ 30

REVENUE FROM CONTRACTS WITH C_3

REVENUE FROM CONTRACTS WITH CUSTOMERS (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Cargo and Other Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 252	$ 248	$ 216
Passenger Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	9,526	8,808	5,499
Passenger [Member] | Cargo and Other Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	128	133	124
Passenger Tickets [Member] | Passenger Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	8,016	7,430	4,533
Passenger Ancillary Services [Member] | Passenger Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	476	447	327
Mileage Plan Services [Member] | Passenger Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	1,034	931	639
Mileage Plan Services, Other [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	648	590	461
Other Services [Member] | Cargo and Other Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 124	$ 115	$ 92

REVENUE FROM CONTRACTS WITH C_4

REVENUE FROM CONTRACTS WITH CUSTOMERS Contract Liabilities Activity (Details) - Mileage Plan Revenue [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Contract with Customer, Liability	$ 2,603	$ 2,497	$ 2,358
Contract with Customer, Liability, Increase From Issuance of Credits	1,197	1,082
Mileage Plan Services, Other [Member]
Contract with Customer, Liability, Revenue Recognized	(117)	(65)
Passenger Services [Member]
Contract with Customer, Liability, Revenue Recognized	$ (974)	$ (878)

REVENUE FROM CONTRACTS WITH C_5

REVENUE FROM CONTRACTS WITH CUSTOMERS Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($) aircraft	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Deferred Revenue Arrangement [Line Items]
Percent of Mileage Breakage	17.40%	17.40%
Contract cost recognized	$ 334	$ 311	$ 90
Receivable	$ 383	296
Number of Partner AIrlines | aircraft	30
Credit Card Receivables	$ 243	201
Prepaid Expenses and Other Current Assets [Member]
Deferred Revenue Arrangement [Line Items]
Capitalized Contract Cost, Net	35	33
Passenger Revenue [Member]
Deferred Revenue Arrangement [Line Items]
Contract with Customer, Liability, Revenue Recognized	823	700
Mileage Plan Revenue [Member]
Deferred Revenue Arrangement [Line Items]
Receivable	$ 102	$ 83

DERIVATIVE INSTRUMENTS - BALANC

DERIVATIVE INSTRUMENTS - BALANCE SHEET CLASSIFICATION (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Derivatives, Fair Value [Line Items]
Accumulated other comprehensive loss	$ (299)	$ (388)	$ (262)	$ (494)
Fuel hedge contracts [Member] | Derivative Instruments Not Designated as Hedges [Member] | Fuel Hedge Contracts, Current [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets, Current	10	33
Fuel hedge contracts [Member] | Derivative Instruments Not Designated as Hedges [Member] | Fuel Hedge Contracts, Noncurrent [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets, Current	1	11
Interest rate swaps agreements [Member] | Derivative Instruments Designated as Hedges [Member] | Prepaid Expenses and Other Current Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets, Current	6	8
Interest rate swaps agreements [Member] | Derivative Instruments Designated as Hedges [Member] | Other Noncurrent Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets, Current	2	7
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	$ (7)	$ 23

DERIVATIVE INSTRUMENTS - INCOME

DERIVATIVE INSTRUMENTS - INCOME STATEMENT (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Gains (losses) recognized in interest income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Loss expected to be reclassified	$ (6)
Interest rate swaps agreements [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Losses recognized in income	8
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]
Gain (Loss) on Derivative Instruments, Net, Pretax	(62)	$ 93	$ 104
Cash Flow Hedging [Member] | Derivative Instruments Designated as Hedges [Member] | Interest rate swaps agreements [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification and Tax	$ (7)	$ 23	$ 17

DERIVATIVE INSTRUMENTS - FAIR V

DERIVATIVE INSTRUMENTS - FAIR VALUE OF HEDGE POSITIONS (Details) gallons in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($) gallons	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Derivative Instruments, Gain (Loss) [Line Items]
Payments for (Proceeds from) Hedge, Investing Activities	$ 29	$ (130)	$ (38)
Interest Income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Price Risk Cash Flow Hedge Unrealized Gain (Loss) to be Reclassified During Next 12 Months	$ 6
Fuel hedge contracts [Member] | Derivative Instruments Not Designated as Hedges [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Nonmonetary Notional Amount | gallons	324
Interest rate swaps agreements [Member] | Secured Debt [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Notional Amount	$ 253

FAIR VALUE MEASUREMENTS - FAIR

FAIR VALUE MEASUREMENTS - FAIR VALUE OF ASSETS AND LIABILITIES (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	$ 1,510
Debt Securities, Available-for-Sale and Held-to-Maturity, Fair Value	1,600
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Marketable securities	1,510	$ 2,079
Assets, Fair Value Disclosure	1,529	2,138
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Marketable securities	392	510
Assets, Fair Value Disclosure	392	510
Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Marketable securities	1,118	1,569
Assets, Fair Value Disclosure	1,137	1,628
Fair Value, Measurements, Recurring [Member] | Fuel hedge contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative instruments, assets	11	44
Fair Value, Measurements, Recurring [Member] | Fuel hedge contracts [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative instruments, assets	0	0
Fair Value, Measurements, Recurring [Member] | Fuel hedge contracts [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative instruments, assets	11	44
Fair Value, Measurements, Recurring [Member] | Interest rate swaps agreements [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative instruments, assets	8	15
Fair Value, Measurements, Recurring [Member] | Interest rate swaps agreements [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative instruments, assets	0	0
Fair Value, Measurements, Recurring [Member] | Interest rate swaps agreements [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative instruments, assets	8	15
Fair Value, Measurements, Recurring [Member] | US Treasury and Government [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Marketable securities	387	505
Fair Value, Measurements, Recurring [Member] | US Treasury and Government [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Marketable securities	387	505
Fair Value, Measurements, Recurring [Member] | US Treasury and Government [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Marketable securities	0	0
Fair Value, Measurements, Recurring [Member] | Debt Security, Government, Non-US [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Marketable securities	10	25
Fair Value, Measurements, Recurring [Member] | Debt Security, Government, Non-US [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Marketable securities	0	0
Fair Value, Measurements, Recurring [Member] | Debt Security, Government, Non-US [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Marketable securities	10	25
Fair Value, Measurements, Recurring [Member] | Asset-backed Securities, Securitized Loans and Receivables [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Marketable securities	192	261
Fair Value, Measurements, Recurring [Member] | Asset-backed Securities, Securitized Loans and Receivables [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Marketable securities	0	0
Fair Value, Measurements, Recurring [Member] | Asset-backed Securities, Securitized Loans and Receivables [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Marketable securities	192	261
Fair Value, Measurements, Recurring [Member] | Collateralized Mortgage Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Marketable securities	115	196
Fair Value, Measurements, Recurring [Member] | Collateralized Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Marketable securities	0	0
Fair Value, Measurements, Recurring [Member] | Collateralized Mortgage Backed Securities [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Marketable securities	115	196
Fair Value, Measurements, Recurring [Member] | Corporate Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Marketable securities	763	1,025
Fair Value, Measurements, Recurring [Member] | Corporate Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Marketable securities	0	0
Fair Value, Measurements, Recurring [Member] | Corporate Debt Securities [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Marketable securities	763	1,025
Fair Value, Measurements, Recurring [Member] | US States and Political Subdivisions Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Marketable securities	38	62
Fair Value, Measurements, Recurring [Member] | US States and Political Subdivisions Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Marketable securities	0	0
Fair Value, Measurements, Recurring [Member] | US States and Political Subdivisions Debt Securities [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Marketable securities	38	62
Fair Value, Measurements, Recurring [Member] | Equity funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Marketable securities	5	5
Fair Value, Measurements, Recurring [Member] | Equity funds [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Marketable securities	5	5
Fair Value, Measurements, Recurring [Member] | Equity funds [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Marketable securities	0	$ 0
Fair Value, Measurements, Recurring [Member] | Total Marketable Securities, FV [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Marketable securities	$ 1,500

FAIR VALUE MEASUREMENTS FAIR VA

FAIR VALUE MEASUREMENTS FAIR VALUE MEASUREMENTS - CASH, CASH EQUIVALENTS AND MARKETABLE SECURITIES - MATURITIES (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Cash, Cash Equivalents, and Short-Term Investments [Abstract]
Sales and maturities of marketable securities	$ 1,152	$ 2,252	$ 3,595
Debt Securities, Available-for-sale, Fair Value, Fiscal Year Maturity [Abstract]
Due in one year or less	366
Due after one year through five years	1,091
Due after five years through 10 years	33
Debt Securities, Available-for-sale, Total	1,510
Debt Securities, Available-for-sale, Amortized Cost, Fiscal Year Maturity [Abstract]
Due in one year or less	372
Due after one year through five years	1,126
Due after five years through 10 years	36
Marketable securities	1,555
Debt Securities, Available-for-sale, Maturity, without Single Maturity Date, Amortized Cost	4
Debt Securities, Available-for-Sale, Maturity, Allocated and Single Maturity Date, Rolling after 10 Years, Amortized Cost	17
Debt Securities, Available-for-Sale, Maturity, Allocated and Single Maturity Date, Rolling after 10 Years, Fair Value	15
Debt Securities, Available-for-Sale, Maturity, without Single Maturity Date, Fair Value	$ 5

FAIR VALUE MEASUREMENTS - LONG-

FAIR VALUE MEASUREMENTS - LONG-TERM DEBT (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Fair Value	$ 571
Carrying Amount [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	1,515	$ 1,660
Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	$ 1,382	$ 1,473

LONG-TERM DEBT - SCHEDULE OF LO

LONG-TERM DEBT - SCHEDULE OF LONG-TERM DEBT (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended			21 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2021
Debt Instrument [Line Items]
Long-term Debt	$ 2,471	$ 2,159
Less debt issuance costs	(15)	(15)
Less current portion	289	276
Long-term debt, net of current portion	$ 2,182	$ 1,883
Weighted-average fixed-interest rate	3.40%	3.50%
Weighted-average variable-interest rate	6.80%	5.80%
Proceeds from issuance of long-term debt, net of issuance costs	$ 411	$ 0	$ 363
Long-term debt payments	282	385	1,334
Long-term Debt, Fiscal Year Maturity [Abstract]
2024	294
2025	351
2026	307
2027	630
2028	114
Thereafter	790
Long-term Debt	2,486
Proceeds from Issuance of Long-term Debt	595
Unsecured Term Loan through PSP of CARES Act	$ 600	600
Adjustments to Additional Paid in Capital, Warrant Issued			16
Long-term Debt, Weighted Average Interest Rate, at Point in Time	4.40%
Proceeds from Issuance of Long-term Debt	$ 595
Adjustments to Additional Paid in Capital, Warrant Issued			$ 16
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 39.06
Scheduled debt payments [Member]
Debt Instrument [Line Items]
Long-term debt payments	$ 282
Fixed-rate notes payable due through 2029
Debt Instrument [Line Items]
Long-term Debt	80	113
Variable-rate notes payable due through 2035
Debt Instrument [Line Items]
Long-term Debt	971	514
Fixed-rate EETC payable due through 2027 [Member]
Debt Instrument [Line Items]
Long-term Debt	835	$ 947
US Treasury CARES Act Loan
Long-term Debt, Fiscal Year Maturity [Abstract]
Adjustments to Additional Paid in Capital, Warrant Issued				$ 30
Adjustments to Additional Paid in Capital, Warrant Issued				$ 30
Proceeds from Issuance of Long-Term Debt, Noncash proceeds
Long-term Debt, Fiscal Year Maturity [Abstract]
Proceeds from Issuance of Long-term Debt	179
Proceeds from Issuance of Long-term Debt	179
Proceeds from Issuance of Long-Term Debt, Cash proceeds
Long-term Debt, Fiscal Year Maturity [Abstract]
Proceeds from Issuance of Long-term Debt	416
Proceeds from Issuance of Long-term Debt	$ 416

LONG-TERM DEBT LONG-TERM DEBT -

LONG-TERM DEBT LONG-TERM DEBT - SECURED DEBT (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Debt Instrument [Line Items]
Long-term Debt	$ 2,471	$ 2,159
Long-term debt payments	282	385	$ 1,334
Proceeds from Issuance of Debt	$ 411	$ 0	$ 363

LONG-TERM DEBT - LINE OF CREDIT

LONG-TERM DEBT - LINE OF CREDIT (Details) $ in Millions	Dec. 31, 2023 USD ($) credit_facility
Line of Credit Facility [Line Items]
Line of credit facility, borrowing capacity	$ 626
Number of credit facilities | credit_facility	3
Line of credit facility, asset restrictions, unrestricted cash and marketable securities	$ 500
Credit Facility 1 [Member] | Secured by other [Member]
Line of Credit Facility [Line Items]
Line of credit facility, borrowing capacity	150
Credit Facility 2 [Member] | Secured by aircraft [Member]
Line of Credit Facility [Line Items]
Line of credit facility, borrowing capacity	400
Credit Facility 3 [Member] | Secured by aircraft [Member]
Line of Credit Facility [Line Items]
Line of credit facility, borrowing capacity	$ 76

LEASES - NARRATIVE (Details)

LEASES - NARRATIVE (Details) $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($) aircraft	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Lessee, Lease, Description [Line Items]
Sublease Income	$ 15	$ 15	$ 16
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	178	461	273
Operating Lease, Payments	348
Finance Lease, Principal Payments	$ 211
Finance leased asset, Number of units | aircraft	1
Lessor, Operating Lease, Lease Not yet Commenced, Assumption and Judgment, Value of Underlying Asset, Amount	$ 47
E175 [Member] | Maximum [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Term of Contract	11 years
B737 MAX [Member] | Maximum [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Term of Contract	12 years
B-737-800F | Maximum [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Term of Contract	11 years
Property Subject to Operating Lease [Member] | E175 [Member]
Lessee, Lease, Description [Line Items]
Operating leases, number of leased assets (in aircraft) | aircraft	42
Property Subject to Operating Lease [Member] | B737-800
Lessee, Lease, Description [Line Items]
Operating leases, number of leased assets (in aircraft) | aircraft	10
Property Subject to Operating Lease [Member] | B737 MAX [Member]
Lessee, Lease, Description [Line Items]
Operating leases, number of leased assets (in aircraft) | aircraft	14
Property Subject to Operating Lease [Member] | A320, nonop [Member]
Lessee, Lease, Description [Line Items]
Operating leases, number of leased assets (in aircraft) | aircraft	16
Property Subject to Operating Lease [Member] | B-737-800F
Lessee, Lease, Description [Line Items]
Operating leases, number of leased assets (in aircraft) | aircraft	1
Airport Facilities [Member]
Lessee, Lease, Description [Line Items]
Variable Lease, Cost	$ 447	381	377
Aircraft Leases [Member]
Lessee, Lease, Description [Line Items]
Variable Lease, Cost	10	10	5
Corporate real estate [Member]
Lessee, Lease, Description [Line Items]
Variable Lease, Cost	$ 15	$ 27	$ 17

LEASES - Schedule of Leased Ass

LEASES - Schedule of Leased Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Lessee, Lease, Description [Line Items]
Operating Lease, Right-of-Use Asset	$ 1,195	$ 1,471
Operating Lease, Expense	690	708	$ 654
Sublease Income	(15)	(15)	(16)
Lease, Cost	675	693	638
Aircraft Leases [Member]
Lessee, Lease, Description [Line Items]
Operating Lease, Right-of-Use Asset	468	701
Operating Lease, Cost	100	191	174
CPA Aircraft [Member]
Lessee, Lease, Description [Line Items]
Operating Lease, Right-of-Use Asset	622	683
Operating Lease, Cost	108	100	80
Airport Facilities [Member]
Lessee, Lease, Description [Line Items]
Operating Lease, Right-of-Use Asset	29	21
Operating Lease, Cost	451	384	379
Corporate real estate [Member]
Lessee, Lease, Description [Line Items]
Operating Lease, Right-of-Use Asset	76	66
Operating Lease, Cost	$ 31	$ 33	$ 21

LEASES - Lease Cost (Details)

LEASES - Lease Cost (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Lessee, Lease, Description [Line Items]
Operating Lease, Expense	$ 690	$ 708	$ 654
Sublease Income	15	15	16
Lease, Cost	675	693	638
Aircraft Leases [Member]
Lessee, Lease, Description [Line Items]
Operating Lease, Cost	$ 100	191	174
Operating Lease, Weighted Average Discount Rate, Percent	5.50%
Operating Lease, Weighted Average Remaining Lease Term	9 years 3 months 18 days
CPA Aircraft [Member]
Lessee, Lease, Description [Line Items]
Operating Lease, Cost	$ 108	100	80
Operating Lease, Weighted Average Discount Rate, Percent	7%
Operating Lease, Weighted Average Remaining Lease Term	7 years 9 months 18 days
Airport Facilities [Member]
Lessee, Lease, Description [Line Items]
Operating Lease, Cost	$ 451	384	379
Operating Lease, Weighted Average Discount Rate, Percent	5.30%
Operating Lease, Weighted Average Remaining Lease Term	6 years 8 months 12 days
Corporate real estate [Member]
Lessee, Lease, Description [Line Items]
Operating Lease, Cost	$ 31	$ 33	$ 21
Operating Lease, Weighted Average Discount Rate, Percent	5.40%
Operating Lease, Weighted Average Remaining Lease Term	26 years 7 months 6 days

LEASES - Maturity of Lease Liab

LEASES - Maturity of Lease Liabilities (Details) $ in Millions	Dec. 31, 2023 USD ($)
Aircraft Leases [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Liability, Payments, Due Next Twelve Months	$ 162
Lessee, Operating Lease, Liability, Payments, Due Year Two	72
Lessee, Operating Lease, Liability, Payments, Due Year Three	75
Lessee, Operating Lease, Liability, Payments, Due Year Four	71
Lessee, Operating Lease, Liability, Payments, Due Year Five	64
Lessee, Operating Lease, Liability, Payments, Due after Year Five	306
Lessee, Operating Lease, Liability, Payments, Due	750
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	145
Operating Lease, Liability	605
CPA Aircraft [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Liability, Payments, Due Next Twelve Months	112
Lessee, Operating Lease, Liability, Payments, Due Year Two	112
Lessee, Operating Lease, Liability, Payments, Due Year Three	112
Lessee, Operating Lease, Liability, Payments, Due Year Four	112
Lessee, Operating Lease, Liability, Payments, Due Year Five	110
Lessee, Operating Lease, Liability, Payments, Due after Year Five	276
Lessee, Operating Lease, Liability, Payments, Due	834
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	191
Operating Lease, Liability	643
Airport Facilities [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Liability, Payments, Due Next Twelve Months	5
Lessee, Operating Lease, Liability, Payments, Due Year Two	6
Lessee, Operating Lease, Liability, Payments, Due Year Three	6
Lessee, Operating Lease, Liability, Payments, Due Year Four	5
Lessee, Operating Lease, Liability, Payments, Due Year Five	5
Lessee, Operating Lease, Liability, Payments, Due after Year Five	9
Lessee, Operating Lease, Liability, Payments, Due	36
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	6
Operating Lease, Liability	30
Corporate real estate [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Liability, Payments, Due Next Twelve Months	10
Lessee, Operating Lease, Liability, Payments, Due Year Two	9
Lessee, Operating Lease, Liability, Payments, Due Year Three	9
Lessee, Operating Lease, Liability, Payments, Due Year Four	8
Lessee, Operating Lease, Liability, Payments, Due Year Five	7
Lessee, Operating Lease, Liability, Payments, Due after Year Five	112
Lessee, Operating Lease, Liability, Payments, Due	155
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	74
Operating Lease, Liability	$ 81

INCOME TAXES - DEFERRED TAX ASS

INCOME TAXES - DEFERRED TAX ASSETS AND LIABILITIES (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Income Tax Disclosure [Abstract]
Excess of tax over book depreciation	$ 1,605	$ 1,312
Deferred Tax Liabilities, Intangible Assets	16	17
Deferred Tax Liabilities, Other	3	49
Gross deferred tax liabilities	1,916	1,734
Mileage Plan	(455)	(436)
Inventory obsolescence	(23)	(21)
Employee benefits	(159)	(145)
Net operating losses	(166)	(28)
Other - net	(77)	(88)
Deferred tax assets	(1,237)	(1,177)
Valuation allowance	16	17
Net deferred tax liabilities	695	574
Operating Loss Carryforwards [Line Items]
Valuation allowance	16	17
Deferred Tax Liabilities, Other Finite-Lived Assets	292	356
Deferred Tax Assets - Leasing Arrangement	329	392
Deferred Tax Assets, Leasehold Maintenance	(28)	$ (67)
Federal [Member]
Operating Loss Carryforwards [Line Items]
Net operating loss	684
Income Taxes Receivable	4
State [Member]
Operating Loss Carryforwards [Line Items]
Net operating loss	$ 467

INCOME TAXES - COMPONENTS OF TA

INCOME TAXES - COMPONENTS OF TAX EXPENSE (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Current tax expense (benefit):
Federal	$ (3)	$ (11)	$ 40
State	(4)	(3)	16
Total current	(7)	(14)	56
Deferred tax expense:
Federal	82	32	80
State	13	3	15
Total deferred	95	35	95
Income tax expense	$ 88	$ 21	$ 151

INCOME TAXES - EFFECTIVE INCOME

INCOME TAXES - EFFECTIVE INCOME TAX RECONCILIATION (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Business Acquisition [Line Items]
U.S. federal tax rate	21%	35%	35%
Income before income tax	$ 323	$ 79	$ 629
Expected tax expense	68	17	132
Nondeductible expenses	14	11	10
State income taxes	17	5	20
Valuation allowance	(1)	(4)	1
Tax credits	(3)	(5)	(2)
FIN48 reserve	(5)	(1)	3
Tax law changes	0	0	(14)
Effective Income Tax Rate Reconciliation State and Local Income Sourcing, Amount	(5)	(2)	0
Other—net	3	0	1
Income tax expense	$ 88	$ 21	$ 151
Effective tax rate	27.10%	26.20%	24%

INCOME TAXES INCOME TAXES - UNC

INCOME TAXES INCOME TAXES - UNCERTAIN TAX POSITIONS (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Tax Contingency [Line Items]
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	$ 20
Income Tax Examination, Penalties and Interest Accrued	2	$ 3	$ 8
Income Tax Examination, Penalties and Interest Expense		5	2
Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities	3	20	0
Beginning balance	21	41	35
Additions related to prior years	0	0	3
Releases related to prior years	0	(1)	0
Additions related to current year activity	9	1	3
Releases due to settlements	(3)	(20)	0
Releases due to lapse of statute of limitations	(2)	0	0
Ending balance	$ 25	$ 21	$ 41

INCOME TAXES INCOME TAXES NARRA

INCOME TAXES INCOME TAXES NARRATIVE (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Tax law changes	$ 0	$ 0	$ (14)
Income Taxes Paid	16
Federal [Member]
Operating Loss Carryforwards [Line Items]
Income Taxes Receivable	$ 4

INCOME TAXES NEW ACCOUNTING STA

INCOME TAXES NEW ACCOUNTING STANDARDS (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Other Special Items [Line Items]
Deferred Tax Liabilities, Other	$ 3	$ 49
Valuation allowance	$ 16	$ 17

EMPLOYEE BENEFIT PLANS EMPLOYEE

EMPLOYEE BENEFIT PLANS EMPLOYEE BENEFIT PLANS - ADDITIONAL INFORMATION (Details)	12 Months Ended
	Dec. 31, 2023 plan
Business Acquisition [Line Items]
Number of Qualified Defined Benefit Plans	4
Number of defined benefit plans	1
Number of defined contribution plans	8

EMPLOYEE BENEFIT PLANS - ASSUMP

EMPLOYEE BENEFIT PLANS - ASSUMPTIONS (Details) - Qualified Defined Benefit [Member]	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Minimum [Member]
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation [Abstract]
Benefit obligations, Weighted-average discount rate	5.14%	5.41%
Benefit obligations, Rate of compensation increase	2.01%	2.01%
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Net period benefit costs, Weighted-average discount rate	5.41%	2.82%	2.43%
Net period benefit costs, Weighted-average expected return on assets	5%	3%	3%
Net period benefit costs, Rate of compensation increase	2.01%	2.02%	2.02%
Maximum [Member]
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation [Abstract]
Benefit obligations, Weighted-average discount rate	5.16%	5.42%
Benefit obligations, Rate of compensation increase	2.34%	2.35%
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Net period benefit costs, Weighted-average discount rate	5.42%	2.90%	2.58%
Net period benefit costs, Weighted-average expected return on assets	6.50%	5.25%	5.50%
Net period benefit costs, Rate of compensation increase	2.35%	2.38%	2.43%

EMPLOYEE BENEFIT PLANS - PLAN A

EMPLOYEE BENEFIT PLANS - PLAN ASSETS (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Qualified Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	$ 2,023	$ 1,894	$ 2,695
Plan asset allocations	100%	100%
Qualified Defined Benefit [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	$ 1,956	$ 1,811
Qualified Defined Benefit [Member] | Fixed Income Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan asset allocations	45%	45%
Qualified Defined Benefit [Member] | Credit bond index fund [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	$ 1,061	$ 1,001
Qualified Defined Benefit [Member] | Real Estate [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan asset allocations	4%	5%
Qualified Defined Benefit [Member] | Real Estate [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	$ 60	$ 76
Qualified Defined Benefit [Member] | Cash Equivalents [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	$ 7	$ 7
Qualified Defined Benefit [Member] | Defined Benefit Plan, Equity Securities, US
Defined Benefit Plan Disclosure [Line Items]
Plan asset allocations	36%	35%
Qualified Defined Benefit [Member] | Defined Benefit Plan, Equity Securities, US | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	$ 634	$ 568
Qualified Defined Benefit [Member] | Defined Benefit Plan, Equity Securities, Non-US
Defined Benefit Plan Disclosure [Line Items]
Plan asset allocations	15%	15%
Qualified Defined Benefit [Member] | Defined Benefit Plan, Equity Securities, Non-US | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	$ 261	$ 242
Qualified Defined Benefit Plan - Salaried [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan asset allocations	100%	100%
Qualified Defined Benefit Plan - Salaried [Member] | Fixed Income Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan asset allocations	90%	90%
Qualified Defined Benefit Plan - Salaried [Member] | Real Estate [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan asset allocations	0%	0%
Qualified Defined Benefit Plan - Salaried [Member] | Defined Benefit Plan, Equity Securities, US
Defined Benefit Plan Disclosure [Line Items]
Plan asset allocations	7%	7%
Qualified Defined Benefit Plan - Salaried [Member] | Defined Benefit Plan, Equity Securities, Non-US
Defined Benefit Plan Disclosure [Line Items]
Plan asset allocations	3%	3%
Minimum [Member] | Qualified Defined Benefit [Member] | Fixed Income Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Investment Policy and Strategy, Description	37
Minimum [Member] | Qualified Defined Benefit [Member] | Real Estate [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Investment Policy and Strategy, Description	0
Minimum [Member] | Qualified Defined Benefit [Member] | Defined Benefit Plan, Equity Securities, US
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Investment Policy and Strategy, Description	29
Minimum [Member] | Qualified Defined Benefit [Member] | Defined Benefit Plan, Equity Securities, Non-US
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Investment Policy and Strategy, Description	9
Minimum [Member] | Qualified Defined Benefit Plan - Salaried [Member] | Fixed Income Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Investment Policy and Strategy, Description	85
Minimum [Member] | Qualified Defined Benefit Plan - Salaried [Member] | Real Estate [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Investment Policy and Strategy, Description	0
Minimum [Member] | Qualified Defined Benefit Plan - Salaried [Member] | Defined Benefit Plan, Equity Securities, US
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Investment Policy and Strategy, Description	2
Minimum [Member] | Qualified Defined Benefit Plan - Salaried [Member] | Defined Benefit Plan, Equity Securities, Non-US
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Investment Policy and Strategy, Description	0
Maximum [Member] | Qualified Defined Benefit [Member] | Fixed Income Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Investment Policy and Strategy, Description	57
Maximum [Member] | Qualified Defined Benefit [Member] | Real Estate [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Investment Policy and Strategy, Description	10
Maximum [Member] | Qualified Defined Benefit [Member] | Defined Benefit Plan, Equity Securities, US
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Investment Policy and Strategy, Description	39
Maximum [Member] | Qualified Defined Benefit [Member] | Defined Benefit Plan, Equity Securities, Non-US
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Investment Policy and Strategy, Description	19
Maximum [Member] | Qualified Defined Benefit Plan - Salaried [Member] | Fixed Income Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Investment Policy and Strategy, Description	95
Maximum [Member] | Qualified Defined Benefit Plan - Salaried [Member] | Defined Benefit Plan, Equity Securities, US
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Investment Policy and Strategy, Description	12
Maximum [Member] | Qualified Defined Benefit Plan - Salaried [Member] | Defined Benefit Plan, Equity Securities, Non-US
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Investment Policy and Strategy, Description	8

EMPLOYEE BENEFIT PLANS - FUNDED

EMPLOYEE BENEFIT PLANS - FUNDED STATUS (Details) - Qualified Defined Benefit [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Benefit obligation
Beginning of year	$ 2,079	$ 2,758
Service cost	29	45	$ 52
Actuarial (gain) loss	83	(628)
Defined Benefit Plan, Benefit Obligation, Benefits Paid	(116)	(172)
End of year	2,183	2,079	2,758
Defined Benefit Plan Service Cost, including early-out expense	29	46
Defined Benefit Plan, Benefit Obligation, Special and Contractual Termination Benefits	0	9
Defined Benefit Interest Cost, PBO	108	66
Plan assets at fair value
Beginning of year	1,894	2,695
Actual return on plan assets	245	(629)
Defined Benefit Plan, Plan Assets, Benefits Paid	(116)	(172)
End of year	2,023	1,894	$ 2,695
Funded status (unfunded)	$ (160)	$ (185)
Percent funded	93%	91%
Accumulated benefit obligation	$ 2,100	$ 2,000
Defined Benefit Plan, Plan Assets, Benefits Paid	$ 116	$ 172

EMPLOYEE BENEFIT PLANS - AMOUNT

EMPLOYEE BENEFIT PLANS - AMOUNTS RECOGNIZED IN CONSOLIDATED BALANCE SHEETS (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Liability, Defined Benefit Plan [Abstract]
Accrued benefit liability-long term	$ (362)	$ (348)
Qualified Defined Benefit [Member]
Liability, Defined Benefit Plan [Abstract]
Accrued benefit liability-long term	(245)	(240)
Plan assets-long term (within Other noncurrent assets)	85	55
Total liability recognized	(160)	(185)
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax [Abstract]
Prior service cost (credit)	6	6
Net loss	367	438
Amount recognized in AOCL (pretax)	$ 373	$ 444

EMPLOYEE BENEFIT PLANS - EXPECT

EMPLOYEE BENEFIT PLANS - EXPECTED AMORTIZATION FROM AOCI (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Qualified Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Expected Return (Loss) on Plan Assets	$ 114	$ 128	$ 122

EMPLOYEE BENEFIT PLANS - NET PE

EMPLOYEE BENEFIT PLANS - NET PENSION EXPENSE (Details) - Qualified Defined Benefit [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	$ 29	$ 45	$ 52
Interest cost	108	65	56
Defined Benefit Plan, Benefit Obligation, Special and Contractual Termination Benefits	0	9
Defined Benefit Plan, Expected Return (Loss) on Plan Assets	114	128	122
Amortization of prior service cost	0	(1)	(1)
Defined Benefit Plan, Amortization of Gain (Loss)	(23)	(8)	(37)
Net pension expense (benefit)	$ 46	$ (11)	$ 22

EMPLOYEE BENEFIT PLANS - FUTURE

EMPLOYEE BENEFIT PLANS - FUTURE BENEFITS EXPECTED TO BE PAID (Details) $ in Millions	Dec. 31, 2023 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year	$ 30
Qualified Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
2024	113
2025	131
2026	139
2027	154
2028	163
2029-2033	$ 854

EMPLOYEE BENEFIT PLANS EMPLOY_2

EMPLOYEE BENEFIT PLANS EMPLOYEE BENEFIT PLANS - POSTRETIREMENT MEDICAL BENEFITS (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Postretirement Medical Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Benefit obligation	$ 98	$ 89

EMPLOYEE BENEFIT PLANS - DEFINE

EMPLOYEE BENEFIT PLANS - DEFINED CONTRIBUTION PLANS (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Retirement Benefits [Abstract]
Total expense for the defined-contribution plans	$ 203	$ 160	$ 125

EMPLOYEE BENEFIT PLANS - PILOT

EMPLOYEE BENEFIT PLANS - PILOT LONG-TERM DISABILITY BENEFITS (Details) - Postretirement Health Coverage [Member] - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Defined Benefit Plan Disclosure [Line Items]
Total liability net of a prefunded trust account	$ 72	$ 69
Prefunded trust account	$ 10	$ 11

EMPLOYEE BENEFIT PLANS - EMPLOY

EMPLOYEE BENEFIT PLANS - EMPLOYEE INCENTIVE-PAY PLANS (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Retirement Benefits [Abstract]
Operational Performance Rewards Program entitles all Air Group employees to maximum quarterly payouts (in dollars per quarter)	450
Variable incentive pay	$ 200,000,000	$ 257,000,000	$ 151,000,000

EMPLOYEE BENEFIT PLANS - PROJEC

EMPLOYEE BENEFIT PLANS - PROJECTED BENEFIT OBLIGATION (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Pension Plan with Projected Benefit Obligation in Excess of Plan Assets, Projected Benefit Obligation	$ 1,403	$ 1,332
Defined Benefit Plan, Plan with Accumulated Benefit Obligation in Excess of Plan Assets, Accumulated Benefit Obligation	1,327	1,267
Defined Benefit Plan, Plan with Accumulated Benefit Obligation in Excess of Plan Assets, Plan Assets	$ 1,158	$ 1,092

COMMITMENTS AND CONTINGENCIES_2

COMMITMENTS AND CONTINGENCIES COMMITMENTS AND CONTINGENCIES (Details) $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($) aircraft
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Commited to purchase (in aircraft) | aircraft	204
Finance leased asset, Number of units | aircraft	1
Firm aircraft commitment [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Commited to purchase (in aircraft) | aircraft	89
Aircraft option and other rights [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Commited to purchase (in aircraft) | aircraft	115
Minimum [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Loss Contingency, Range of Possible Loss, Portion Not Accrued	$ 10
Loss Contingency, Range of Possible Loss, Portion Not Accrued	10
Maximum [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Loss Contingency, Range of Possible Loss, Portion Not Accrued	160
Loss Contingency, Range of Possible Loss, Portion Not Accrued	160
Virgin Group trademark license agreement
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Loss Contingency, Damages Sought, Value	8
Loss Contingency, Damages Sought, Value	8
Aircraft Commitments [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
2024	1,252
2025	1,366
2026	1,097
2027	600
2028	151
Thereafter	716
Total	5,182
Capacity Purchase Agreements[Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
2024	235
2025	230
2026	224
2027	220
2028	223
Thereafter	515
Total	$ 1,647
B737 MAX [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Commited to purchase (in aircraft) | aircraft	185
B737 MAX [Member] | Firm aircraft commitment [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Commited to purchase (in aircraft) | aircraft	80
B737 MAX [Member] | Aircraft option and other rights [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Commited to purchase (in aircraft) | aircraft	105
A321neo [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Number of Aircraft Operated | aircraft	10
E175 [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Commited to purchase (in aircraft) | aircraft	19
E175 [Member] | Firm aircraft commitment [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Commited to purchase (in aircraft) | aircraft	9
E175 [Member] | Aircraft option and other rights [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Commited to purchase (in aircraft) | aircraft	10
Property Subject to Operating Lease [Member] | B737-800
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Operating leases, number of leased assets (in aircraft) | aircraft	10
Property Subject to Operating Lease [Member] | B737 MAX [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Operating leases, number of leased assets (in aircraft) | aircraft	14
Property Subject to Operating Lease [Member] | E175 [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Operating leases, number of leased assets (in aircraft) | aircraft	42

SHAREHOLDER'S EQUITY SHAREHOLDE

SHAREHOLDER'S EQUITY SHAREHOLDERS' EQUITY - STOCK CHANGES (Details)	Dec. 31, 2023 $ / shares shares
Equity [Abstract]
Common stock, shares authorized | shares	400,000,000
Common stock, par value | $ / shares	$ 0.01

SHAREHOLDER'S EQUITY - COMMON S

SHAREHOLDER'S EQUITY - COMMON STOCK REPURCHASE (Details) - USD ($) $ in Millions	12 Months Ended	100 Months Ended
	Dec. 31, 2023	Dec. 31, 2023	Aug. 31, 2015
Equity, Class of Treasury Stock [Line Items]
Common stock repurchase (in shares)	3,520,533
Common stock repurchase	$ 145
Stock Repurchase Program, Remaining Authorized Repurchase Amount	312	$ 312
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)		11,100,000
Common stock repurchase	$ 145	$ 688

SHAREHOLDER'S EQUITY SHAREHOL_2

SHAREHOLDER'S EQUITY SHAREHOLDERS' EQUITY - OTHER (Details) - shares	Dec. 31, 2023	Dec. 31, 2022
Equity [Abstract]
Treasury Stock, Common, Shares	9,349,944	12,870,477

SHAREHOLDER'S EQUITY SHAREHOL_3

SHAREHOLDER'S EQUITY SHAREHOLDERS' EQUITY - ACCUMULATED OTHER COMPREHENSIVE LOSS (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss	$ (299)	$ (388)	$ (262)	$ (494)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	$ 64	$ (134)	$ 211

SHAREHOLDER'S EQUITY CARES Act

SHAREHOLDER'S EQUITY CARES Act Issuance (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended	21 Months Ended
	Dec. 31, 2021	Dec. 31, 2021	Dec. 31, 2023	Dec. 31, 2022
Class of Warrant or Right [Line Items]
Class of Warrant or Right, Exercise Price of Warrants or Rights			$ 39.06
Class of Warrant or Right, Number of Securities Called by Warrants or Rights			1,455,437
Class of Warrant or Right, Outstanding			1,882,517
Adjustments to Additional Paid in Capital, Warrant Issued	$ 16
US Treasury CARES Act Loan
Class of Warrant or Right [Line Items]
Adjustments to Additional Paid in Capital, Warrant Issued		$ 30
CARES Act Loan Program Warrants
Class of Warrant or Right [Line Items]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights				427,080

ACCUMULATED OTHER COMPREHENSI_2

ACCUMULATED OTHER COMPREHENSIVE LOSS (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss	$ (299)	$ (388)	$ (262)	$ (494)
AOCI Tax, Attributable to Parent	97	122	83	160
Reclassification from AOCI, Current Period, Tax	(7)	(4)	(6)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	25	8	21
Other Comprehensive Income (Loss), Tax	(18)	43	(71)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	64	(134)	211
AOCI - Marketable Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI before Tax, Attributable to Parent	(46)	(104)	(5)	30
Reclassification from AOCI, Current Period, before Tax, Attributable to Parent	13	9	(6)
Other Comprehensive Income (Loss), before Reclassifications, before Tax	45	(108)	(29)
AOCI - Employee Benefit Plan [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI before Tax, Attributable to Parent	(358)	(421)	(332)	(659)
Reclassification from AOCI, Current Period, before Tax, Attributable to Parent	19	3	33
Other Comprehensive Income (Loss), before Reclassifications, before Tax	44	(92)	294
AOCI - Interest Rate Derivatives [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI before Tax, Attributable to Parent	8	15	(8)	$ (25)
Reclassification from AOCI, Current Period, before Tax, Attributable to Parent	0	0	0
Other Comprehensive Income (Loss), before Reclassifications, before Tax	$ (7)	$ 23	$ 17

STOCK-BASED COMPENSATION PLAN_2

STOCK-BASED COMPENSATION PLANS (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 59	$ 35	$ 44
Tax benefit related to stock-based compensation	14	9	11
Unrecognized stock-based compensation for non-vested options and awards	$ 27
Unrecognized stock-based compensation awards weighted-average period	1 year 7 months 6 days
Shares authorized under stock-based compensation plans (in shares)	20,000,000
Shares remaining available for future grants (shares)	9,000,000
Stock options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 2	$ 3	$ 5
Unrecognized stock-based compensation for non-vested options and awards	$ 1
Unrecognized stock-based compensation awards weighted-average period	0 days
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Expected volatility	46%	44%	43%
Expected term	6 years	6 years	6 years
Risk-free interest rate	3.64%	1.91%	0.68%
Expected dividend yield	0%	0%	0%
Weighted-average grant date fair value per share (in dollars per share)	$ 16.77	$ 23.36	$ 23.66
Estimated fair value of options granted (millions)	$ 1	$ 4	$ 4
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding, beginning balance (in shares)	1,230,757
Granted (in Shares)	50,120
Exercised (in shares)	(24,996)
Canceled (in shares)	(86,475)
Forfeited or expired (in shares)	(7,976)
Outstanding, ending balance (in shares)	1,161,430	1,230,757
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)	$ 61.45
Granted, Weighted-Average Exercise Price Per Share (in dollars per share)	58.54
Exercised, Weighted-Average Exercise Price Per Share (in dollars per share)	35.44
Canceled, Weighted-Average Exercise Price Per Share (in dollars per share)	68.95
Fofeited or expired, Weighted-Average Exercise Price Per Share (in dollars per share)	56.37
Outstanding, ending balance, Weighted-Average Exercise Price Per Share (in dollars per share)	$ 61.36	$ 61.45
Outstanding, Weighted-Average Contractual Life	5 years 1 month 6 days	5 years 7 months 6 days
Outstanding, Aggregate Intrinsic Value	$ 0	$ 1
Exercisable, Outstanding (in shares)	883,061
Exercisable, Weighted-Average Exercise Price Per Share (in dollars per share)	$ 62.84
Exercisable, Weighted-Average Contractual Life	4 years 6 months
Exercisable, Aggregate Intrinsic Value	$ 0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest [Abstract]
Vested or expected to vest, Shares	1,161,430
Vested or expected to vest, Weighted-Average Exercise Price Per Share (in dollars per share)	$ 61.36
Vested or expected to vest, Weighted-Average Contractual Life	5 years 1 month 6 days
Vested or expected to vest, Aggregate Intrinsic Value	$ 0
Intrinsic value of option exercises	0	0	3
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	4	4	4
Stock awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	39	$ 14	20
Unrecognized stock-based compensation for non-vested options and awards	$ 26
Unrecognized stock-based compensation awards weighted-average period	1 year 7 months 6 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)	106,760
Granted (in shares)	1,245,008
Vested (in shares)	(389,231)
Forfeited (in shares)	(93,753)
Non-vested, ending balance (in shares)	868,784	106,760
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)	$ 53.97
Granted, Weighted-Average Grant Date Fair Value (in dollars per share)	51.99
Vested, Weighted-Average Grant Date Fair Value (in dollars per share)	51.03
Forfeited, Weighted-Average Grant Date Fair Value (in dollars per share)	61.97
Non-vested, ending balance, Weighted-Average Price Per Share (in dollars per share)	$ 51.95	$ 53.97
Non-vested, Weighted-Average Contractual Life	1 year 8 months 12 days	2 years 10 months 24 days
Non-vested, Total Instrinsic Value (in dollars)	$ 34	$ 11
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	$ 17	$ 17	$ 18
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Granted (in shares)	1,855,608	1,292,489	1,254,393
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%
Share-based Compensation Arrangement by Share-based Payment Award, Maximum Employee Subscription Rate	10%

OPERATING SEGMENT INFORMATION_2

OPERATING SEGMENT INFORMATION (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Operating revenues
Total Operating Revenues		$ 10,426	$ 9,646	$ 6,176
Operating expenses
Operating expenses, excluding fuel		7,391	6,908	4,212
Economic fuel		2,641	2,668	1,279
Total Operating Expenses		10,032	9,576	5,491
Nonoperating Income (Expense) [Abstract]
Investment Income, Interest		80	53	25
Interest Expense		(121)	(108)	(128)
Interest Costs Capitalized Adjustment		27	14	11
Other - net		(39)	50	36
Nonoperating Income (Expense) Total		(71)	9	(56)
Income before income tax		323	79	629
Depreciation		451	415	394
Payments to Acquire Property, Plant, and Equipment (including non-cash)		1,673	1,671	$ 292
Total assets		$ 14,613	$ 14,186
Pretax Margin, Adjusted		7.50%	7.60%	(5.60%)
Pretax Margin, GAAP		3.10%	0.80%	10.20%
Air Group Adjusted [Member]
Operating revenues
Total Operating Revenues		$ 10,426	$ 9,646	$ 6,176
Operating expenses
Operating expenses, excluding fuel		6,948	6,328	5,137
Economic fuel		2,643	2,592	1,326
Total Operating Expenses		9,591	8,920	6,463
Nonoperating Income (Expense) [Abstract]
Nonoperating Income (Expense) Total		(53)	9	(56)
Income before income tax		782	735	(343)
Horizon [Member]
Operating revenues
Total Operating Revenues		374	359	406
Operating expenses
Operating expenses, excluding fuel		344	383	373
Economic fuel		0	0	0
Total Operating Expenses		344	383	373
Nonoperating Income (Expense) [Abstract]
Nonoperating Income (Expense) Total		(41)	(22)	(21)
Income before income tax		(11)	(46)	12
Depreciation		48	64	71
Payments to Acquire Property, Plant, and Equipment (including non-cash)		200	127	56
Total assets		1,352	1,157
Consolidating & Other
Operating revenues
Total Operating Revenues		(366)	(355)	(402)
Operating expenses
Operating expenses, excluding fuel		(358)	(356)	(433)
Economic fuel		0	0	0
Total Operating Expenses		(358)	(356)	(433)
Nonoperating Income (Expense) [Abstract]
Nonoperating Income (Expense) Total		3	1	3
Income before income tax		(5)	2	34
Total assets		(6,676)	(6,704)
Special Charges [Member]
Operating revenues
Total Operating Revenues		0	0	0
Operating expenses
Operating expenses, excluding fuel		443	580	(925)
Economic fuel		(2)	76	(47)
Total Operating Expenses		441	656	(972)
Nonoperating Income (Expense) [Abstract]
Nonoperating Income (Expense) Total		(18)	0	0
Income before income tax		(459)	(656)	972
Alaska Mainline [Member]
Operating revenues
Total Operating Revenues		8,940	8,236	5,025
Operating expenses
Operating expenses, excluding fuel		5,841	5,216	4,101
Economic fuel		2,264	2,195	1,065
Total Operating Expenses		8,105	7,411	5,166
Nonoperating Income (Expense) [Abstract]
Nonoperating Income (Expense) Total		(15)	30	(38)
Income before income tax		820	855	(179)
Depreciation	[1]	403	351	323
Payments to Acquire Property, Plant, and Equipment (including non-cash)	[1]	1,473	1,544	236
Total assets	[1]	19,937	19,733
Alaska Regional [Member]
Operating revenues
Total Operating Revenues		1,478	1,406	1,147
Operating expenses
Operating expenses, excluding fuel		1,121	1,085	1,096
Economic fuel		379	397	261
Total Operating Expenses		1,500	1,482	1,357
Nonoperating Income (Expense) [Abstract]
Nonoperating Income (Expense) Total		0	0	0
Income before income tax		(22)	(76)	(210)
Passenger Revenue [Member]
Operating revenues
Revenue from Contract with Customer, Excluding Assessed Tax		9,526	8,808	5,499
Passenger Revenue [Member] | Air Group Adjusted [Member]
Operating revenues
Revenue from Contract with Customer, Excluding Assessed Tax		9,526	8,808	5,499
Passenger Revenue [Member] | Horizon [Member]
Operating revenues
Revenue from Contract with Customer, Excluding Assessed Tax		0	0	0
Passenger Revenue [Member] | Consolidating & Other
Operating revenues
Revenue from Contract with Customer, Excluding Assessed Tax		0	0	0
Passenger Revenue [Member] | Special Charges [Member]
Operating revenues
Revenue from Contract with Customer, Excluding Assessed Tax		0	0	0
Passenger Revenue [Member] | Alaska Mainline [Member]
Operating revenues
Revenue from Contract with Customer, Excluding Assessed Tax		8,097	7,454	4,411
Passenger Revenue [Member] | Alaska Regional [Member]
Operating revenues
Revenue from Contract with Customer, Excluding Assessed Tax		1,429	1,354	1,088
Capacity Purchase Agreements [Member]
Operating revenues
Revenue from Contract with Customer, Excluding Assessed Tax		0	0	0
Capacity Purchase Agreements [Member] | Air Group Adjusted [Member]
Operating revenues
Revenue from Contract with Customer, Excluding Assessed Tax		0	0	0
Capacity Purchase Agreements [Member] | Horizon [Member]
Operating revenues
Revenue from Contract with Customer, Excluding Assessed Tax		374	359	406
Capacity Purchase Agreements [Member] | Consolidating & Other
Operating revenues
Revenue from Contract with Customer, Excluding Assessed Tax		(374)	(359)	(406)
Capacity Purchase Agreements [Member] | Special Charges [Member]
Operating revenues
Revenue from Contract with Customer, Excluding Assessed Tax		0	0	0
Capacity Purchase Agreements [Member] | Alaska Mainline [Member]
Operating revenues
Revenue from Contract with Customer, Excluding Assessed Tax		0	0	0
Capacity Purchase Agreements [Member] | Alaska Regional [Member]
Operating revenues
Revenue from Contract with Customer, Excluding Assessed Tax		0	0	0
Mileage Plan Services, Other [Member]
Operating revenues
Revenue from Contract with Customer, Excluding Assessed Tax		648	590	461
Mileage Plan Services, Other [Member] | Air Group Adjusted [Member]
Operating revenues
Revenue from Contract with Customer, Excluding Assessed Tax		648	590	461
Mileage Plan Services, Other [Member] | Horizon [Member]
Operating revenues
Revenue from Contract with Customer, Excluding Assessed Tax		0	0	0
Mileage Plan Services, Other [Member] | Consolidating & Other
Operating revenues
Revenue from Contract with Customer, Excluding Assessed Tax		0	0	0
Mileage Plan Services, Other [Member] | Special Charges [Member]
Operating revenues
Revenue from Contract with Customer, Excluding Assessed Tax		0	0	0
Mileage Plan Services, Other [Member] | Alaska Mainline [Member]
Operating revenues
Revenue from Contract with Customer, Excluding Assessed Tax		599	538	402
Mileage Plan Services, Other [Member] | Alaska Regional [Member]
Operating revenues
Revenue from Contract with Customer, Excluding Assessed Tax		49	52	59
Cargo and Freight [Member]
Operating revenues
Revenue from Contract with Customer, Excluding Assessed Tax		252	248	216
Cargo and Freight [Member] | Air Group Adjusted [Member]
Operating revenues
Revenue from Contract with Customer, Excluding Assessed Tax		252	248	216
Cargo and Freight [Member] | Horizon [Member]
Operating revenues
Revenue from Contract with Customer, Excluding Assessed Tax		0	0	0
Cargo and Freight [Member] | Consolidating & Other
Operating revenues
Revenue from Contract with Customer, Excluding Assessed Tax		8	4	4
Cargo and Freight [Member] | Special Charges [Member]
Operating revenues
Revenue from Contract with Customer, Excluding Assessed Tax		0	0	0
Cargo and Freight [Member] | Alaska Mainline [Member]
Operating revenues
Revenue from Contract with Customer, Excluding Assessed Tax		244	244	212
Cargo and Freight [Member] | Alaska Regional [Member]
Operating revenues
Revenue from Contract with Customer, Excluding Assessed Tax		$ 0	$ 0	$ 0
[1] NOTE 8. 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. The Company has a net deferred tax liability, primarily due to differences in depreciation rates for federal income tax purposes and for financial reporting purposes. Deferred tax (assets) and liabilities comprise the following (in millions): 2023 2022 Excess of tax over book depreciation $ 1,605 $ 1,312 Intangibles - net 16 17 Operating lease assets 292 356 Other - net 3 49 Deferred tax liabilities 1,916 1,734 Mileage Plan (455) (436) Inventory obsolescence (23) (21) Employee benefits (159) (145) Net operating losses (166) (28) Operating lease liabilities (329) (392) Leasehold maintenance (28) (67) Other - net (77) (88) Deferred tax assets (1,237) (1,177) Valuation allowance 16 17 Net deferred tax liabilities $ 695 $ 574 At December 31, 2023, the Company has paid taxes of $16 million and does not expect to pay any additional tax for 2023. The Company is also awaiting payment of a $4 million federal tax refund receivable as a result of carrying back capital losses and credits to previous tax years. The Company also has gross state and local NOLs of approximately $467 million that expire beginning in 2025 and continuing through 2043. Current federal NOLs in the amount of $684 million will be carried forward and have an indefinite life. Valuation allowances are provided to reduce the related deferred income tax assets to an amount which will, more likely than not, be realized. The Company has determined it is more likely than not that a portion of the federal capital loss carryforward and state NOL carryforward will not be realized and, therefore has provided a valuation allowance of $16 million for that portion as of December 31, 2023. The Company has likewise concluded it is more likely than not that all of its federal and the remaining state deferred income tax assets will be realized and thus no additional valuation allowance has been recorded. The Company reassesses the need for a valuation allowance each reporting period. Components of Income Tax Expense The components of income tax expense are as follows (in millions): 2023 2022 2021 Current income tax (benefit) expense: Federal $ (3) $ (11) $ 40 State (4) (3) 16 Total current income tax (benefit) expense (7) (14) 56 Deferred income tax expense: Federal 82 32 80 State 13 3 15 Total deferred income tax expense 95 35 95 Income tax expense $ 88 $ 21 $ 151 Income Tax Rate Reconciliation Income tax expense reconciles to the amount computed by applying the 2023 U.S. federal rate of 21% to income before income tax and for deferred taxes as follows (in millions): 2023 2022 2021 Income before income tax $ 323 $ 79 $ 629 Expected tax expense 68 17 132 Nondeductible expenses 14 11 10 State income tax expense 17 5 20 Tax law changes — — (14) State income sourcing (5) (2) — Valuation allowance (1) (4) 1 Tax credits (3) (5) (2) Uncertain tax positions (5) (1) 3 Other - net 3 — 1 Actual tax expense $ 88 $ 21 $ 151 Effective tax rate (a) 27.1 % 26.2 % 24.0 % (a) Figures in the table above are rounded to the nearest million. As a result, a manual recalculation of the effective tax rate using these rounded figures may not agree directly to the Company's actual effective tax rate shown in the table. 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 2020 to 2022 Alaska 2018 to 2022 California 2007 to 2022 Oregon 2015 to 2022 Certain tax years are open to the extent of net operating loss carryforwards. Changes in the liability for gross unrecognized tax benefits during 2023, 2022 and 2021 are as follows (in millions): 2023 2022 2021 Balance at January 1 $ 21 $ 41 $ 35 Additions related to prior years — — 3 Releases related to prior years — (1) — Additions related to current year activity 9 1 3 Releases due to settlements (3) (20) — Releases due to lapse of statute of limitations (2) — — Balance at December 31 $ 25 $ 21 $ 41 As of December 31, 2023, the Company had $25 million of accrued tax contingencies, of which $20 million, if fully recognized, would decrease the effective tax rate. As of December 31, 2023, 2022 and 2021, the Company has accrued interest and penalties, net of federal income tax benefit, of $2 million, $3 million, and $8 million. In 2023, 2022, and 2021, the Company recognized an immaterial benefit, a benefit of $5 million, and expense of $2 million for interest and penalties, net of federal income tax benefit. At December 31, 2023, the Company has unrecognized tax benefits recorded as a liability. These uncertain tax positions could change because of the Company's ongoing audits, settlement of issues, new audits, and status of other taxpayer court cases. The Company cannot predict the timing of these actions.

Business Combinations and Ass_2

Business Combinations and Asset Acquisitions (Details) $ / shares in Units, $ in Billions	Dec. 02, 2023 USD ($) $ / shares
Business Acquisition, Equity Interests Issued or Issuable [Line Items]
Business Acquisition, Amount Per Share Paid To Each Holder of Record | $ / shares	$ 18
Business Acquisition , Amount Paid To Each Holder Of Record | $	$ 1