CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Operating Revenues
Total Operating Revenues	$ 9,646	$ 6,176	$ 3,566
Operating Expenses
Wages and benefits	2,640	2,218	2,053
Payroll Support Program Grant Recognized	0	(914)	(782)
Variable incentive pay	257	151	130
Aircraft fuel, including hedging gains and losses	2,668	1,279	723
Aircraft maintenance	424	364	321
Aircraft rent	291	254	299
Landing fees and other rentals	581	555	417
Contracted services	329	235	181
Selling expenses	295	173	101
Depreciation and amortization	415	394	420
Cost of Services, Catering	197	139	90
Third-party regional carrier expense	182	147	128
Other operating expenses	717	507	407
Special Items - Impairment charges and other	496	(1)	627
Restructuring Charges	0	(10)	220
Special items - merger-related costs	0	0	6
Special items—other	84	(10)	220
Total Operating Expenses	9,576	5,491	5,341
Operating Income (Loss), Total	70	685	(1,775)
Nonoperating Income (Expense) [Abstract]
Investment Income, Interest	53	25	31
Interest Expense	(108)	(128)	(98)
Interest Costs Capitalized Adjustment	14	11	11
Special Items - Net non-operating	0	0	(26)
Other - net	50	36	17
Nonoperating Income (Expense) Total	9	(56)	(65)
Income before income tax	79	629	(1,840)
Income Tax Expense, Before Tax Cuts and Jobs Act of 2017	21	151	(516)
Income tax expense (benefit)	21	151	(516)
Net Income (Loss)	$ 58	$ 478	$ (1,324)
Basic earnings per share	$ 0.46	$ 3.82	$ (10.72)
Diluted earnings per share	$ 0.45	$ 3.77	$ (10.72)
Shares used for computation:
Basic	126,657	125,063	123,450
Diluted	127,899	126,775	123,450
Mileage Plan Services, Other [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	$ 590	$ 461	$ 374
Cargo and Freight [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	248	216	173
Passenger Revenue [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	8,808	5,499	3,019
Passenger Revenue [Member] | Passenger [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	8,808	5,499	3,019
Mileage Plan Revenue [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	1,521	1,100	720
Mileage Plan Revenue [Member] | Passenger [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	931	639	346
Mileage Plan Revenue [Member] | Mileage Plan Services, Other [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	590	461	374
Cargo and Other Revenue [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	248	216	173
Cargo and Other Revenue [Member] | Cargo and Freight [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	$ 248	$ 216	$ 173