CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	$ 1,953	$ 701	$ 4,277	$ 2,758
Operating Expenses
Wages and benefits	578	495	1,581	1,579
Variable incentive pay	42	42	109	65
PSPGrantRecognized	0	(398)	(914)	(760)
Aircraft fuel, including hedging gains and losses	376	125	853	568
Aircraft maintenance	89	84	272	244
Aircraft rent	64	74	188	229
Landing fees and other rentals	141	109	414	323
Contracted services	62	36	167	138
Selling expenses	49	24	123	83
Depreciation and amortization	99	105	294	320
Food and beverage service	39	14	97	70
Third-party regional carrier expense	39	29	106	92
Other	126	89	348	310
Special items - Impairment charges and other	(9)	121	5	350
Restructuring Charges	0	322	(12)	322
Special items - merger-related costs	0	1	0	5
Costs and Expenses, Total	1,695	1,272	3,631	3,938
Operating Income (Loss)	258	(571)	646	(1,180)
Nonoperating Income (Expense)
Interest income	6	7	19	23
Interest expense	(30)	(34)	(101)	(64)
Interest capitalized	3	4	9	8
Other—net	8	5	27	16
Nonoperating Income (Expense) Total	(13)	(18)	(46)	(17)
Income (Loss) Before Income Tax	245	(589)	600	(1,197)
Income tax (benefit) expense	51	(158)	140	(320)
Net Income (Loss)	$ 194	$ (431)	$ 460	$ (877)
Basic Earnings Per Share (usd per share)	$ 1.55	$ (3.49)	$ 3.69	$ (7.12)
Diluted Earnings Per Share (usd per share)	$ 1.53	$ (3.49)	$ 3.64	$ (7.12)
Shares used for computation:
Basic shares (shares)	125,250,000	123,647,000	124,846,000	123,255,000
Diluted shares (shares)	127,188,000	123,647,000	126,325,000	123,255,000
Passenger [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	$ 1,774	$ 572	$ 3,785	$ 2,362
Mileage plan other revenue [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	120	84	332	266
Cargo and Freight [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	59	45	160	130
Passenger Revenue [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	1,774	572	3,785	2,362
Passenger Revenue [Member] | Passenger [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	1,774	572	3,785	2,362
Mileage Plan Revenue [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	310	148	760	538
Mileage Plan Revenue [Member] | Mileage plan other revenue [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	120	84	332	266
Cargo and Other Revenue [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	59	45	160	130
Cargo and Other Revenue [Member] | Cargo and Freight [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	$ 59	$ 45	$ 160	$ 130