CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended			49 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2020
Operating Revenues
Total Operating Revenues	$ 3,566	$ 8,781	$ 8,264
Operating Expenses
Wages and benefits	2,053	2,370	2,190
Payroll Support Program Grant Recognized	(782)	0	0
Variable incentive pay	130	163	147
Aircraft fuel, including hedging gains and losses	723	1,878	1,936
Aircraft maintenance	321	437	435
Aircraft rent	299	331	315
Landing fees and other rentals	417	531	499
Contracted services	181	289	306
Selling expense	101	313	326
Depreciation and amortization	420	423	398
Cost of Services, Catering	90	214	211
Third-party regional carrier expense	128	166	154
Other operating expenses	407	559	572
Special items - merger-related costs	6	44	87	$ 370
Special Items - Impairment charges and other	627	0	0
Restructuring Charges	220	0	0
Special items—other	0	0	45
Total Operating Expenses	5,341	7,718	7,621
Operating Income (Loss)	(1,775)	1,063	643
Non-operating Income (Expense)
Interest income	31	42	38
Interest expense	(98)	(78)	(91)
Interest capitalized	11	15	18
Special Items - Net non-operating	(26)	0	0
Other - net	17	(26)	(23)
Nonoperating Income (Expense) Total	(65)	(47)	(58)
Income before income tax	(1,840)	1,016	585
Income Tax Expense, Before Tax Cuts and Jobs Act of 2017	(516)	247	148
Income tax (benefit) expense	(516)	247	148
Net Income (Loss)	$ (1,324)	$ 769	$ 437
Basic earnings per share	$ (10.72)	$ 6.24	$ 3.55
Diluted earnings per share	$ (10.72)	$ 6.19	$ 3.52
Shares used for computation:
Basic	123,450	123,279	123,230
Diluted	123,450	124,289	123,975
Cash dividend declared per share	$ 0.375
Mileage Plan Services, Other [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	$ 374	$ 465	$ 434
Cargo and Freight [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	173	221	199
Passenger Revenue [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	3,019	8,095	7,631
Passenger Revenue [Member] | Passenger [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	3,019	8,095	7,631
Mileage Plan Revenue [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	720	1,169	1,053
Mileage Plan Revenue [Member] | Passenger [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	346	704	619
Mileage Plan Revenue [Member] | Mileage Plan Services, Other [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	374	465	434
Cargo and Other Revenue [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	173	221	199
Cargo and Other Revenue [Member] | Cargo and Freight [Member]
Operating Revenues
Revenue from Contract with Customer, Excluding Assessed Tax	$ 173	$ 221	$ 199