Revenue Recognition - Revenue by Geographic Region (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Disaggregation of Revenue [Line Items]
Operating revenue	$ 13,824	$ 7,126	$ 23,173	$ 11,276
Domestic
Disaggregation of Revenue [Line Items]
Operating revenue	10,655	5,894	18,204	9,262
Atlantic
Disaggregation of Revenue [Line Items]
Operating revenue	2,057	467	2,833	734
Latin America
Disaggregation of Revenue [Line Items]
Operating revenue	854	586	1,665	967
Pacific
Disaggregation of Revenue [Line Items]
Operating revenue	258	179	471	313
Passenger
Disaggregation of Revenue [Line Items]
Operating revenue	10,958	5,339	17,865	8,087
Passenger | Domestic
Disaggregation of Revenue [Line Items]
Operating revenue	8,318	4,478	13,881	6,758
Passenger | Atlantic
Disaggregation of Revenue [Line Items]
Operating revenue	1,701	288	2,240	430
Passenger | Latin America
Disaggregation of Revenue [Line Items]
Operating revenue	745	485	1,425	749
Passenger | Pacific
Disaggregation of Revenue [Line Items]
Operating revenue	$ 194	$ 88	$ 319	$ 150