SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) $ in Millions	1 Months Ended	3 Months Ended	12 Months Ended
	Dec. 31, 2022 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2022 USD ($) aircraft	Dec. 31, 2021 USD ($) aircraft	Dec. 31, 2020 USD ($) aircraft	Dec. 31, 2019 USD ($)	Mar. 13, 2019 aircraft
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Incurred storm costs	$ 390
Net income (loss)		$ (220)	$ 539	$ 977	$ (3,074)
Loss on extinguishment			193	28	0
Payroll support and voluntary employee programs, net			0	2,960	967
Other (gains) losses, net			(12)	50	(158)
Stockholders' equity attributable to parent	10,687	10,687	10,687	10,414	8,876	$ 9,832
Impairment charges			$ 28	$ 12	$ 32
Number of aircraft under accelerated retirement | aircraft			10	8	20
Total operating revenues			$ 23,814	$ 15,790	$ 9,048
Advertising costs			224	185	156
Capitalized computer software, net	928	928	928	886
Computer software depreciation expense			$ 232	213	203
Number of aircraft grounded | aircraft							34
Length of agreements with co-brand, payment, and loyalty partners (in years)			10 years
Unionized Employees concentration risk | Workforce Subject to Collective Bargaining Arrangements
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Full-time employees unionized (as a percent)			83.00%
Unionized Employees concentration risk | Number of Employees, Total
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Full-time employees unionized (as a percent)			65.00%
Latin America
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total operating revenues			$ 811	475	184
North America
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total operating revenues			23,000	15,300	8,900
Other Intangible Assets
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Gross carrying amount of indefinite-lived intangible assets	295	295	$ 295	295
Aircraft Residual Value
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Maximum percentage of cost estimated as residual value (as a percent)			18.00%
Minimum percentage of cost estimated residual value (as a percent)			13.00%
Ground property and equipment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Maximum percentage of cost estimated as residual value (as a percent)			10.00%
Minimum percentage of cost estimated residual value (as a percent)			0.00%
Maximum | Flight equipment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Useful life (in years)			25 years
Maximum | Ground property and equipment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Useful life (in years)			30 years
Maximum | Software
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Useful life (in years)			15 years
Minimum | Ground property and equipment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Useful life (in years)			5 years
Minimum | Software
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Useful life (in years)			5 years
Fuel derivative contracts
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Collateral deposits	106	106	$ 106	175
Interest rate derivatives | Other noncurrent liabilities
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Collateral deposits	0	0	0
Retained earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' equity attributable to parent	16,261	16,261	16,261	15,774	14,777	17,945
Accumulated other comprehensive income (loss)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' equity attributable to parent	$ 344	$ 344	$ 344	388	(105)	$ (61)
Cumulative Effect, Period of Adoption, Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' equity attributable to parent				(245)	0
Cumulative Effect, Period of Adoption, Adjustment | Retained earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' equity attributable to parent				$ 55	20
Cumulative Effect, Period of Adoption, Adjustment | Accumulated other comprehensive income (loss)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' equity attributable to parent					$ (20)