Revenue Recognition - Revenue by Geographic Region (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Disaggregation of Revenue [Line Items]
Operating revenue	$ 9,348	$ 4,150
Domestic
Disaggregation of Revenue [Line Items]
Operating revenue	7,549	3,368
Atlantic
Disaggregation of Revenue [Line Items]
Operating revenue	776	267
Latin America
Disaggregation of Revenue [Line Items]
Operating revenue	811	381
Pacific
Disaggregation of Revenue [Line Items]
Operating revenue	212	134
Passenger
Disaggregation of Revenue [Line Items]
Operating revenue	6,907	2,748
Passenger | Domestic
Disaggregation of Revenue [Line Items]
Operating revenue	5,563	2,280
Passenger | Atlantic
Disaggregation of Revenue [Line Items]
Operating revenue	539	142
Passenger | Latin America
Disaggregation of Revenue [Line Items]
Operating revenue	680	264
Passenger | Pacific
Disaggregation of Revenue [Line Items]
Operating revenue	$ 125	$ 62